text: /**
   * Cesium - https://github.com/AnalyticalGraphicsInc/cesium
   *
   * Copyright 2011-2017 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/AnalyticalGraphicsInc/cesium/blob/master/LICENSE.md for full licensing details.
   */
  define(['exports', './when-a55a8a4c', './Check-bc1d37d9', './Math-edfe2d1c', './Cartesian2-52d9479f', './BoundingSphere-ab31357a', './ComponentDatatype-919a7463', './AttributeCompression-4a5b893f'], function (exports, when, Check, _Math, Cartesian2, BoundingSphere, ComponentDatatype, AttributeCompression) { 'use strict';
  
      /**
           * 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.Check.typeOf.object('ellipsoid', ellipsoid);
              //>>includeEnd('debug');
  
              this._ellipsoid = ellipsoid;
              this._cameraPosition = new Cartesian2.Cartesian3();
              this._cameraPositionInScaledSpace = new Cartesian2.Cartesian3();
              this._distanceToLimbInScaledSpaceSquared = 0.0;
  
              // cameraPosition fills in the above values
              if (when.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 = Cartesian2.Cartesian3.magnitudeSquared(cv) - 1.0;
  
                      Cartesian2.Cartesian3.clone(cameraPosition, this._cameraPosition);
                      this._cameraPositionInScaledSpace = cv;
                      this._distanceToLimbInScaledSpaceSquared = vhMagnitudeSquared;
                  }
              }
          });
  
          var scratchCartesian = new Cartesian2.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 Cartesian2.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 (when.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 = Cartesian2.Ellipsoid.clone(Cartesian2.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.Check.typeOf.object('rectangle', rectangle);
              //>>includeEnd('debug');
  
              var positions = Cartesian2.Rectangle.subsample(rectangle, ellipsoid, 0.0, subsampleScratch);
              var bs = BoundingSphere.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 (Cartesian2.Cartesian3.magnitude(bs.center) < 0.1 * ellipsoid.minimumRadius) {
                  return undefined;
              }
  
              return this.computeHorizonCullingPoint(bs.center, positions, result);
          };
  
          var scratchEllipsoidShrunkRadii = new Cartesian2.Cartesian3();
  
          function getPossiblyShrunkEllipsoid(ellipsoid, minimumHeight, result) {
              if (when.defined(minimumHeight) && minimumHeight < 0.0 && ellipsoid.minimumRadius > -minimumHeight) {
                  var ellipsoidShrunkRadii = Cartesian2.Cartesian3.fromElements(
                      ellipsoid.radii.x + minimumHeight,
                      ellipsoid.radii.y + minimumHeight,
                      ellipsoid.radii.z + minimumHeight,
                      scratchEllipsoidShrunkRadii
                  );
                  ellipsoid = Cartesian2.Ellipsoid.fromCartesian3(ellipsoidShrunkRadii, result);
              }
              return ellipsoid;
          }
  
          function computeHorizonCullingPointFromPositions(ellipsoid, directionToPoint, positions, result) {
              //>>includeStart('debug', pragmas.debug);
              Check.Check.typeOf.object('directionToPoint', directionToPoint);
              Check.Check.defined('positions', positions);
              //>>includeEnd('debug');
  
              if (!when.defined(result)) {
                  result = new Cartesian2.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 Cartesian2.Cartesian3();
  
          function computeHorizonCullingPointFromVertices(ellipsoid, directionToPoint, vertices, stride, center, result) {
              //>>includeStart('debug', pragmas.debug);
              Check.Check.typeOf.object('directionToPoint', directionToPoint);
              Check.Check.defined('vertices', vertices);
              Check.Check.typeOf.number('stride', stride);
              //>>includeEnd('debug');
  
              if (!when.defined(result)) {
                  result = new Cartesian2.Cartesian3();
              }
  
              stride = when.defaultValue(stride, 3);
              center = when.defaultValue(center, Cartesian2.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 = Cartesian2.Cartesian3.subtract(occludeeScaledSpacePosition, cv, scratchCartesian);
              var vtDotVc = -Cartesian2.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 / Cartesian2.Cartesian3.magnitudeSquared(vt) > vhMagnitudeSquared);
              return !isOccluded;
          }
  
          var scaledSpaceScratch = new Cartesian2.Cartesian3();
          var directionScratch = new Cartesian2.Cartesian3();
  
          function computeMagnitude(ellipsoid, position, scaledSpaceDirectionToPoint) {
              var scaledSpacePosition = ellipsoid.transformPositionToScaledSpace(position, scaledSpaceScratch);
              var magnitudeSquared = Cartesian2.Cartesian3.magnitudeSquared(scaledSpacePosition);
              var magnitude = Math.sqrt(magnitudeSquared);
              var direction = Cartesian2.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 = Cartesian2.Cartesian3.dot(direction, scaledSpaceDirectionToPoint);
              var sinAlpha = Cartesian2.Cartesian3.magnitude(Cartesian2.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 Cartesian2.Cartesian3.multiplyByScalar(scaledSpaceDirectionToPoint, resultMagnitude, result);
          }
  
          var directionToPointScratch = new Cartesian2.Cartesian3();
  
          function computeScaledSpaceDirectionToPoint(ellipsoid, directionToPoint) {
              if (Cartesian2.Cartesian3.equals(directionToPoint, Cartesian2.Cartesian3.ZERO)) {
                  return directionToPoint;
              }
  
              ellipsoid.transformPositionToScaledSpace(directionToPoint, directionToPointScratch);
              return Cartesian2.Cartesian3.normalize(directionToPointScratch, directionToPointScratch);
          }
  
      /**
       * This enumerated type is used to determine how the vertices of the terrain mesh are compressed.
       *
       * @exports TerrainQuantization
       *
       * @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 Cartesian2.Cartesian3();
      var cartesian3DimScratch = new Cartesian2.Cartesian3();
      var cartesian2Scratch = new Cartesian2.Cartesian2();
      var matrix4Scratch = new BoundingSphere.Matrix4();
      var matrix4Scratch2 = new BoundingSphere.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 (when.defined(axisAlignedBoundingBox) && when.defined(minimumHeight) && when.defined(maximumHeight) && when.defined(fromENU)) {
              var minimum = axisAlignedBoundingBox.minimum;
              var maximum = axisAlignedBoundingBox.maximum;
  
              var dimensions = Cartesian2.Cartesian3.subtract(maximum, minimum, cartesian3DimScratch);
              var hDim = maximumHeight - minimumHeight;
              var maxDim = Math.max(Cartesian2.Cartesian3.maximumComponent(dimensions), hDim);
  
              if (maxDim < SHIFT_LEFT_12 - 1.0) {
                  quantization = TerrainQuantization$1.BITS12;
              } else {
                  quantization = TerrainQuantization$1.NONE;
              }
  
              quantization = TerrainQuantization$1.NONE;//防止精度损失，出现地形模型匹配不上，默认不压缩
  
              center = axisAlignedBoundingBox.center;
              toENU = BoundingSphere.Matrix4.inverseTransformation(fromENU, new BoundingSphere.Matrix4());
  
              var translation = Cartesian2.Cartesian3.negate(minimum, cartesian3Scratch);
              BoundingSphere.Matrix4.multiply(BoundingSphere.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;
              BoundingSphere.Matrix4.multiply(BoundingSphere.Matrix4.fromScale(scale, matrix4Scratch), toENU, toENU);
  
              matrix = BoundingSphere.Matrix4.clone(fromENU);
              BoundingSphere.Matrix4.setTranslation(matrix, Cartesian2.Cartesian3.ZERO, matrix);
  
              fromENU = BoundingSphere.Matrix4.clone(fromENU, new BoundingSphere.Matrix4());
  
              var translationMatrix = BoundingSphere.Matrix4.fromTranslation(minimum, matrix4Scratch);
              var scaleMatrix =  BoundingSphere.Matrix4.fromScale(dimensions, matrix4Scratch2);
              var st = BoundingSphere.Matrix4.multiply(translationMatrix, scaleMatrix,matrix4Scratch);
  
              BoundingSphere.Matrix4.multiply(fromENU, st, fromENU);
              BoundingSphere.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 = when.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 = BoundingSphere.Matrix4.multiplyByPoint(this.toScaledENU, position, cartesian3Scratch);
  
              position.x = _Math.CesiumMath.clamp(position.x, 0.0, 1.0);
              position.y = _Math.CesiumMath.clamp(position.y, 0.0, 1.0);
              position.z = _Math.CesiumMath.clamp(position.z, 0.0, 1.0);
  
              var hDim = this.maximumHeight - this.minimumHeight;
              var h = _Math.CesiumMath.clamp((height - this.minimumHeight) / hDim, 0.0, 1.0);
  
              Cartesian2.Cartesian2.fromElements(position.x, position.y, cartesian2Scratch);
              var compressed0 = AttributeCompression.AttributeCompression.compressTextureCoordinates(cartesian2Scratch);
  
              Cartesian2.Cartesian2.fromElements(position.z, h, cartesian2Scratch);
              var compressed1 = AttributeCompression.AttributeCompression.compressTextureCoordinates(cartesian2Scratch);
  
              Cartesian2.Cartesian2.fromElements(u, v, cartesian2Scratch);
              var compressed2 = AttributeCompression.AttributeCompression.compressTextureCoordinates(cartesian2Scratch);
  
              vertexBuffer[bufferIndex++] = compressed0;
              vertexBuffer[bufferIndex++] = compressed1;
              vertexBuffer[bufferIndex++] = compressed2;
  
              if (this.hasWebMercatorT) {
                  Cartesian2.Cartesian2.fromElements(webMercatorT, 0.0, cartesian2Scratch);
                  var compressed3 = AttributeCompression.AttributeCompression.compressTextureCoordinates(cartesian2Scratch);
                  vertexBuffer[bufferIndex++] = compressed3;
              }
          } else {
              Cartesian2.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.AttributeCompression.octPackFloat(normalToPack);
          }
  
          return bufferIndex;
      };
  
      TerrainEncoding.prototype.decodePosition = function(buffer, index, result) {
          if (!when.defined(result)) {
              result = new Cartesian2.Cartesian3();
          }
  
          index *= this.getStride();
  
          if (this.quantization === TerrainQuantization$1.BITS12) {
              var xy = AttributeCompression.AttributeCompression.decompressTextureCoordinates(buffer[index], cartesian2Scratch);
              result.x = xy.x;
              result.y = xy.y;
  
              var zh = AttributeCompression.AttributeCompression.decompressTextureCoordinates(buffer[index + 1], cartesian2Scratch);
              result.z = zh.x;
  
              return BoundingSphere.Matrix4.multiplyByPoint(this.fromScaledENU, result, result);
          }
  
          result.x = buffer[index];
          result.y = buffer[index + 1];
          result.z = buffer[index + 2];
          return Cartesian2.Cartesian3.add(result, this.center, result);
      };
  
      TerrainEncoding.prototype.decodeTextureCoordinates = function(buffer, index, result) {
          if (!when.defined(result)) {
              result = new Cartesian2.Cartesian2();
          }
  
          index *= this.getStride();
  
          if (this.quantization === TerrainQuantization$1.BITS12) {
              return AttributeCompression.AttributeCompression.decompressTextureCoordinates(buffer[index + 2], result);
          }
  
          return Cartesian2.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.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.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.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.ComponentDatatype.FLOAT;
          var sizeInBytes = ComponentDatatype.ComponentDatatype.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 (!when.defined(result)) {
              result = new TerrainEncoding();
          }
  
          result.quantization = encoding.quantization;
          result.minimumHeight = encoding.minimumHeight;
          result.maximumHeight = encoding.maximumHeight;
          result.center = Cartesian2.Cartesian3.clone(encoding.center);
          result.toScaledENU = BoundingSphere.Matrix4.clone(encoding.toScaledENU);
          result.fromScaledENU = BoundingSphere.Matrix4.clone(encoding.fromScaledENU);
          result.matrix = BoundingSphere.Matrix4.clone(encoding.matrix);
          result.hasVertexNormals = encoding.hasVertexNormals;
          result.hasWebMercatorT = encoding.hasWebMercatorT;
          return result;
      };
  
      exports.EllipsoidalOccluder = EllipsoidalOccluder;
      exports.TerrainEncoding = TerrainEncoding;
  
  });
  