PolylineCollection.js

import BoundingSphere from "../Core/BoundingSphere.js";
import Cartesian2 from "../Core/Cartesian2.js";
import Cartesian3 from "../Core/Cartesian3.js";
import Cartesian4 from "../Core/Cartesian4.js";
import Cartographic from "../Core/Cartographic.js";
import Color from "../Core/Color.js";
import combine from "../Core/combine.js";
import ComponentDatatype from "../Core/ComponentDatatype.js";
import defaultValue from "../Core/defaultValue.js";
import defined from "../Core/defined.js";
import destroyObject from "../Core/destroyObject.js";
import DeveloperError from "../Core/DeveloperError.js";
import EncodedCartesian3 from "../Core/EncodedCartesian3.js";
import FeatureDetection from "../Core/FeatureDetection.js";
import IndexDatatype from "../Core/IndexDatatype.js";
import Intersect from "../Core/Intersect.js";
import CesiumMath from "../Core/Math.js";
import Matrix4 from "../Core/Matrix4.js";
import Plane from "../Core/Plane.js";
import RuntimeError from "../Core/RuntimeError.js";
import Buffer from "../Renderer/Buffer.js";
import BufferUsage from "../Renderer/BufferUsage.js";
import ContextLimits from "../Renderer/ContextLimits.js";
import DrawCommand from "../Renderer/DrawCommand.js";
import Pass from "../Renderer/Pass.js";
import RenderState from "../Renderer/RenderState.js";
import ShaderProgram from "../Renderer/ShaderProgram.js";
import ShaderSource from "../Renderer/ShaderSource.js";
import Texture from "../Renderer/Texture.js";
import VertexArray from "../Renderer/VertexArray.js";
import PolylineCommon from "../Shaders/PolylineCommon.js";
import PolylineFS from "../Shaders/PolylineFS.js";
import PolylineVS from "../Shaders/PolylineVS.js";
import BatchTable from "./BatchTable.js";
import BlendingState from "./BlendingState.js";
import Material from "./Material.js";
import Polyline from "./Polyline.js";
import SceneMode from "./SceneMode.js";

var SHOW_INDEX = Polyline.SHOW_INDEX;
var WIDTH_INDEX = Polyline.WIDTH_INDEX;
var POSITION_INDEX = Polyline.POSITION_INDEX;
var MATERIAL_INDEX = 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 = Polyline.POSITION_SIZE_INDEX;
var DISTANCE_DISPLAY_CONDITION = Polyline.DISTANCE_DISPLAY_CONDITION;
var NUMBER_OF_PROPERTIES = Polyline.NUMBER_OF_PROPERTIES;

var attributeLocations = {
  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);
  this._polylines = [];
  this._polylineBuckets = {};

  // The buffer usage is determined based on the usage of the attribute over time.
  this._positionBufferUsage = {
    bufferUsage: BufferUsage.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(collection, context) {
  if (defined(collection._batchTable)) {
    collection._batchTable.destroy();
  }

  var attributes = [
    {
      functionName: "batchTable_getWidthAndShow",
      componentDatatype: ComponentDatatype.UNSIGNED_BYTE,
      componentsPerAttribute: 2,
    },
    {
      functionName: "batchTable_getPickColor",
      componentDatatype: ComponentDatatype.UNSIGNED_BYTE,
      componentsPerAttribute: 4,
      normalize: true,
    },
    {
      functionName: "batchTable_getCenterHigh",
      componentDatatype: ComponentDatatype.FLOAT,
      componentsPerAttribute: 3,
    },
    {
      functionName: "batchTable_getCenterLowAndRadius",
      componentDatatype: ComponentDatatype.FLOAT,
      componentsPerAttribute: 4,
    },
    {
      functionName: "batchTable_getDistanceDisplayCondition",
      componentDatatype: ComponentDatatype.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(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(this, context);
    this._createBatchTable = false;
  }

  if (this._createVertexArray || computeNewBuffersUsage(this)) {
    createVertexArrays(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.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] || properties[MATERIAL_INDEX]) {
      createVertexArrays(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]) {
                bucket.writeUpdate(
                  index,
                  polyline,
                  this._positionBuffer,
                  projection
                );
              }
              break;
            }
            index += polylineBuckets[x].lengthOfPositions;
          }
        }

        if (properties[SHOW_INDEX] || properties[WIDTH_INDEX]) {
          this._batchTable.setBatchedAttribute(
            polyline._index,
            0,
            new Cartesian2(polyline._width, polyline._show)
          );
        }

        if (this._batchTable.attributes.length > 2) {
          if (properties[POSITION_INDEX] || properties[POSITION_SIZE_INDEX]) {
            var boundingSphere =
              frameState.mode === SceneMode.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]) {
            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; ++k) {
    properties[k] = 0;
  }

  var modelMatrix = Matrix4.IDENTITY;
  if (frameState.mode === SceneMode.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.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.TRANSLUCENT : Pass.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.SCENE3D) {
          boundingVolume = polyline._boundingVolumeWC;
        } else if (frameState.mode === SceneMode.COLUMBUS_VIEW) {
          boundingVolume = polyline._boundingVolume2D;
        } else if (frameState.mode === SceneMode.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.TRANSLUCENT
          : Pass.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]) {
    if (bufferUsage.bufferUsage !== BufferUsage.STREAM_DRAW) {
      usageChanged = true;
      bufferUsage.bufferUsage = BufferUsage.STREAM_DRAW;
      bufferUsage.frameCount = 100;
    } else {
      bufferUsage.frameCount = 100;
    }
  } else if (bufferUsage.bufferUsage !== BufferUsage.STATIC_DRAW) {
    if (bufferUsage.frameCount === 0) {
      usageChanged = true;
      bufferUsage.bufferUsage = BufferUsage.STATIC_DRAW;
    } else {
      bufferUsage.frameCount--;
    }
  }

  return usageChanged;
}

var emptyVertexBuffer = [0.0, 0.0, 0.0];

function createVertexArrays(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.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.STATIC_DRAW;

    collection._positionBuffer = Buffer.createVertexBuffer({
      context: context,
      typedArray: positionArray,
      usage: positionBufferUsage,
    });
    var position3DBuffer;
    if (defined(position3DArray)) {
      position3DBuffer = Buffer.createVertexBuffer({
        context: context,
        typedArray: position3DArray,
        usage: positionBufferUsage,
      });
    }
    collection._texCoordExpandAndBatchIndexBuffer = Buffer.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.createIndexBuffer({
          context: context,
          typedArray: indicesArray,
          usage: BufferUsage.STATIC_DRAW,
          indexDatatype: IndexDatatype.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.position3DHigh,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: positionHighOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.position3DLow,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: positionLowOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.position2DHigh,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: positionHighOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.position2DLow,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: positionLowOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.prevPosition3DHigh,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: prevPositionHighOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.prevPosition3DLow,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: prevPositionLowOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.prevPosition2DHigh,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: prevPositionHighOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.prevPosition2DLow,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: prevPositionLowOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.nextPosition3DHigh,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: nextPositionHighOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.nextPosition3DLow,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: nextPositionLowOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.nextPosition2DHigh,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: nextPositionHighOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.nextPosition2DLow,
            componentsPerAttribute: 3,
            componentDatatype: ComponentDatatype.FLOAT,
            offsetInBytes: nextPositionLowOffset,
            strideInBytes: 6 * positionSizeInBytes,
          },
          {
            index: attributeLocations.texCoordExpandAndBatchIndex,
            componentsPerAttribute: 4,
            componentDatatype: ComponentDatatype.FLOAT,
            vertexBuffer: collection._texCoordExpandAndBatchIndexBuffer,
            offsetInBytes: vertexTexCoordExpandAndBatchIndexBufferOffset,
          },
        ];

        var buffer3D;
        var bufferProperty3D;
        var buffer2D;
        var bufferProperty2D;

        if (mode === SceneMode.SCENE3D) {
          buffer3D = collection._positionBuffer;
          bufferProperty3D = "vertexBuffer";
          buffer2D = emptyVertexBuffer;
          bufferProperty2D = "value";
        } else if (
          mode === SceneMode.SCENE2D ||
          mode === SceneMode.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 = [];
function createMaterialId(material) {
  var uniforms = Material._uniformList[material.type];
  var length = uniforms.length;
  scratchUniformArray.length = 2.0 * length;

  var index = 0;
  for (var i = 0; i < length; ++i) {
    var uniform = uniforms[i];
    scratchUniformArray[index] = uniform;
    scratchUniformArray[index + 1] = material._uniforms[uniform]();
    index += 2;
  }

  return material.type + ":" + JSON.stringify(scratchUniformArray, 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(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,
  });
};

function intersectsIDL(polyline) {
  return (
    Cartesian3.dot(Cartesian3.UNIT_X, polyline._boundingVolume.center) < 0 ||
    polyline._boundingVolume.intersectPlane(Plane.ORIGIN_ZX_PLANE) ===
      Intersect.INTERSECTING
  );
}

PolylineBucket.prototype.getPolylinePositionsLength = function (polyline) {
  var length;
  if (this.mode === SceneMode.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.SCENE2D) {
        scratchWritePrevPosition.z = 0.0;
        scratchWritePosition.z = 0.0;
        scratchWriteNextPosition.z = 0.0;
      }

      if (mode === SceneMode.SCENE2D || mode === SceneMode.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.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.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 = new Cartographic();

PolylineBucket.prototype.getSegments = function (polyline, projection) {
  var positions = polyline._actualPositions;

  if (this.mode === SceneMode.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)
      )
    );
  }

  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.SCENE2D) {
        scratchWritePrevPosition.z = 0.0;
        scratchWritePosition.z = 0.0;
        scratchWriteNextPosition.z = 0.0;
      }

      if (mode === SceneMode.SCENE2D || mode === SceneMode.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
    );
  }
};
export default PolylineCollection;