@cesium/engine/Source/Scene/GlobeSurfaceTileProvider.js

CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.

import BoundingSphere from "../Core/BoundingSphere.js";
import BoxOutlineGeometry from "../Core/BoxOutlineGeometry.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 clone from "../Core/clone.js";
import Color from "../Core/Color.js";
import ColorGeometryInstanceAttribute from "../Core/ColorGeometryInstanceAttribute.js";
import combine from "../Core/combine.js";
import defined from "../Core/defined.js";
import destroyObject from "../Core/destroyObject.js";
import DeveloperError from "../Core/DeveloperError.js";
import Event from "../Core/Event.js";
import GeometryInstance from "../Core/GeometryInstance.js";
import GeometryPipeline from "../Core/GeometryPipeline.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 NearFarScalar from "../Core/NearFarScalar.js";
import OrientedBoundingBox from "../Core/OrientedBoundingBox.js";
import OrthographicFrustum from "../Core/OrthographicFrustum.js";
import PrimitiveType from "../Core/PrimitiveType.js";
import Rectangle from "../Core/Rectangle.js";
import SphereOutlineGeometry from "../Core/SphereOutlineGeometry.js";
import VerticalExaggeration from "../Core/VerticalExaggeration.js";
import TerrainQuantization from "../Core/TerrainQuantization.js";
import Visibility from "../Core/Visibility.js";
import WebMercatorProjection from "../Core/WebMercatorProjection.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 VertexArray from "../Renderer/VertexArray.js";
import BlendingState from "./BlendingState.js";
import ClippingPlaneCollection from "./ClippingPlaneCollection.js";
import ClippingPolygonCollection from "./ClippingPolygonCollection.js";
import DepthFunction from "./DepthFunction.js";
import GlobeSurfaceTile from "./GlobeSurfaceTile.js";
import ImageryLayer from "./ImageryLayer.js";
import ImageryState from "./ImageryState.js";
import PerInstanceColorAppearance from "./PerInstanceColorAppearance.js";
import Primitive from "./Primitive.js";
import QuadtreeTileLoadState from "./QuadtreeTileLoadState.js";
import SceneMode from "./SceneMode.js";
import ShadowMode from "./ShadowMode.js";
import TerrainFillMesh from "./TerrainFillMesh.js";
import TerrainState from "./TerrainState.js";
import TileBoundingRegion from "./TileBoundingRegion.js";
import TileSelectionResult from "./TileSelectionResult.js";

/**
 * Provides quadtree tiles representing the surface of the globe.  This type is intended to be used
 * with {@link QuadtreePrimitive}.
 *
 * @alias GlobeSurfaceTileProvider
 * @constructor
 *
 * @param {TerrainProvider} options.terrainProvider The terrain provider that describes the surface geometry.
 * @param {ImageryLayerCollection} option.imageryLayers The collection of imagery layers describing the shading of the surface.
 * @param {GlobeSurfaceShaderSet} options.surfaceShaderSet The set of shaders used to render the surface.
 *
 * @private
 */
function GlobeSurfaceTileProvider(options) {
  //>>includeStart('debug', pragmas.debug);
  if (!defined(options)) {
    throw new DeveloperError("options is required.");
  }
  if (!defined(options.terrainProvider)) {
    throw new DeveloperError("options.terrainProvider is required.");
  } else if (!defined(options.imageryLayers)) {
    throw new DeveloperError("options.imageryLayers is required.");
  } else if (!defined(options.surfaceShaderSet)) {
    throw new DeveloperError("options.surfaceShaderSet is required.");
  }
  //>>includeEnd('debug');

  this.lightingFadeOutDistance = 6500000.0;
  this.lightingFadeInDistance = 9000000.0;
  this.hasWaterMask = false;
  this.showWaterEffect = false;
  this.oceanNormalMap = undefined;
  this.zoomedOutOceanSpecularIntensity = 0.5;
  this.enableLighting = false;
  this.dynamicAtmosphereLighting = false;
  this.dynamicAtmosphereLightingFromSun = false;
  this.showGroundAtmosphere = false;
  this.shadows = ShadowMode.RECEIVE_ONLY;
  this.vertexShadowDarkness = 0.3;

  /**
   * The color to use to highlight terrain fill tiles. If undefined, fill tiles are not
   * highlighted at all. The alpha value is used to alpha blend with the tile's
   * actual color. Because terrain fill tiles do not represent the actual terrain surface,
   * it may be useful in some applications to indicate visually that they are not to be trusted.
   * @type {Color}
   * @default undefined
   */
  this.fillHighlightColor = undefined;

  this.hueShift = 0.0;
  this.saturationShift = 0.0;
  this.brightnessShift = 0.0;

  this.showSkirts = true;
  this.backFaceCulling = true;
  this.undergroundColor = undefined;
  this.undergroundColorAlphaByDistance = undefined;

  this.lambertDiffuseMultiplier = 0.0;

  this.materialUniformMap = undefined;
  this._materialUniformMap = undefined;

  this._quadtree = undefined;
  this._terrainProvider = options.terrainProvider;
  this._imageryLayers = options.imageryLayers;
  this._surfaceShaderSet = options.surfaceShaderSet;

  this._renderState = undefined;
  this._blendRenderState = undefined;
  this._disableCullingRenderState = undefined;
  this._disableCullingBlendRenderState = undefined;

  this._errorEvent = new Event();

  this._removeLayerAddedListener =
    this._imageryLayers.layerAdded.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerAdded,
      this,
    );
  this._removeLayerRemovedListener =
    this._imageryLayers.layerRemoved.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerRemoved,
      this,
    );
  this._removeLayerMovedListener =
    this._imageryLayers.layerMoved.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerMoved,
      this,
    );
  this._removeLayerShownListener =
    this._imageryLayers.layerShownOrHidden.addEventListener(
      GlobeSurfaceTileProvider.prototype._onLayerShownOrHidden,
      this,
    );
  this._imageryLayersUpdatedEvent = new Event();

  this._layerOrderChanged = false;

  this._tilesToRenderByTextureCount = [];
  this._drawCommands = [];
  this._uniformMaps = [];
  this._usedDrawCommands = 0;

  this._vertexArraysToDestroy = [];

  this._debug = {
    wireframe: false,
    boundingSphereTile: undefined,
  };

  this._baseColor = undefined;
  this._firstPassInitialColor = undefined;
  this.baseColor = new Color(0.0, 0.0, 0.5, 1.0);

  /**
   * A property specifying a {@link ClippingPlaneCollection} used to selectively disable rendering on the outside of each plane.
   * @type {ClippingPlaneCollection}
   * @private
   */
  this._clippingPlanes = undefined;

  /**
   * A property specifying a {@link ClippingPolygonCollection} used to selectively disable rendering inside or outside a list of polygons.
   * @type {ClippingPolygonCollection}
   * @private
   */
  this._clippingPolygons = undefined;

  /**
   * A property specifying a {@link Rectangle} used to selectively limit terrain and imagery rendering.
   * @type {Rectangle}
   */
  this.cartographicLimitRectangle = Rectangle.clone(Rectangle.MAX_VALUE);

  this._hasLoadedTilesThisFrame = false;
  this._hasFillTilesThisFrame = false;

  this._oldVerticalExaggeration = undefined;
  this._oldVerticalExaggerationRelativeHeight = undefined;
}

Object.defineProperties(GlobeSurfaceTileProvider.prototype, {
  /**
   * Gets or sets the color of the globe when no imagery is available.
   * @memberof GlobeSurfaceTileProvider.prototype
   * @type {Color}
   */
  baseColor: {
    get: function () {
      return this._baseColor;
    },
    set: function (value) {
      //>>includeStart('debug', pragmas.debug);
      if (!defined(value)) {
        throw new DeveloperError("value is required.");
      }
      //>>includeEnd('debug');

      this._baseColor = value;
      this._firstPassInitialColor = Cartesian4.fromColor(
        value,
        this._firstPassInitialColor,
      );
    },
  },
  /**
   * Gets or sets the {@link QuadtreePrimitive} for which this provider is
   * providing tiles.  This property may be undefined if the provider is not yet associated
   * with a {@link QuadtreePrimitive}.
   * @memberof GlobeSurfaceTileProvider.prototype
   * @type {QuadtreePrimitive}
   */
  quadtree: {
    get: function () {
      return this._quadtree;
    },
    set: function (value) {
      //>>includeStart('debug', pragmas.debug);
      if (!defined(value)) {
        throw new DeveloperError("value is required.");
      }
      //>>includeEnd('debug');

      this._quadtree = value;
    },
  },

  /**
   * Gets the tiling scheme used by the provider.
   * @memberof GlobeSurfaceTileProvider.prototype
   * @type {TilingScheme}
   */
  tilingScheme: {
    get: function () {
      if (!defined(this._terrainProvider)) {
        return undefined;
      }

      return this._terrainProvider.tilingScheme;
    },
  },

  /**
   * Gets an event that is raised when the geometry provider encounters an asynchronous error.  By subscribing
   * to the event, you will be notified of the error and can potentially recover from it.  Event listeners
   * are passed an instance of {@link TileProviderError}.
   * @memberof GlobeSurfaceTileProvider.prototype
   * @type {Event}
   */
  errorEvent: {
    get: function () {
      return this._errorEvent;
    },
  },

  /**
   * Gets an event that is raised when an imagery layer is added, shown, hidden, moved, or removed.
   * @memberof GlobeSurfaceTileProvider.prototype
   * @type {Event}
   */
  imageryLayersUpdatedEvent: {
    get: function () {
      return this._imageryLayersUpdatedEvent;
    },
  },

  /**
   * Gets or sets the terrain provider that describes the surface geometry.
   * @memberof GlobeSurfaceTileProvider.prototype
   * @type {TerrainProvider}
   */
  terrainProvider: {
    get: function () {
      return this._terrainProvider;
    },
    set: function (terrainProvider) {
      if (this._terrainProvider === terrainProvider) {
        return;
      }

      this._terrainProvider = terrainProvider;

      if (defined(this._quadtree)) {
        this._quadtree.invalidateAllTiles();
      }
    },
  },
  /**
   * The {@link ClippingPlaneCollection} used to selectively disable rendering.
   *
   * @type {ClippingPlaneCollection}
   *
   * @private
   */
  clippingPlanes: {
    get: function () {
      return this._clippingPlanes;
    },
    set: function (value) {
      ClippingPlaneCollection.setOwner(value, this, "_clippingPlanes");
    },
  },

  /**
   * The {@link ClippingPolygonCollection} used to selectively disable rendering inside or outside a list of polygons.
   *
   * @type {ClippingPolygonCollection}
   *
   * @private
   */
  clippingPolygons: {
    get: function () {
      return this._clippingPolygons;
    },
    set: function (value) {
      ClippingPolygonCollection.setOwner(value, this, "_clippingPolygons");
    },
  },
});

function sortTileImageryByLayerIndex(a, b) {
  let aImagery = a.loadingImagery;
  if (!defined(aImagery)) {
    aImagery = a.readyImagery;
  }

  let bImagery = b.loadingImagery;
  if (!defined(bImagery)) {
    bImagery = b.readyImagery;
  }

  return aImagery.imageryLayer._layerIndex - bImagery.imageryLayer._layerIndex;
}

/**
 * Make updates to the tile provider that are not involved in rendering. Called before the render update cycle.
 */
GlobeSurfaceTileProvider.prototype.update = function (frameState) {
  // update collection: imagery indices, base layers, raise layer show/hide event
  this._imageryLayers._update();
};

function updateCredits(surface, frameState) {
  const creditDisplay = frameState.creditDisplay;
  const terrainProvider = surface._terrainProvider;
  if (defined(terrainProvider) && defined(terrainProvider.credit)) {
    creditDisplay.addCreditToNextFrame(terrainProvider.credit);
  }

  const imageryLayers = surface._imageryLayers;
  for (let i = 0, len = imageryLayers.length; i < len; ++i) {
    const layer = imageryLayers.get(i);
    if (layer.ready && layer.show && defined(layer.imageryProvider.credit)) {
      creditDisplay.addCreditToNextFrame(layer.imageryProvider.credit);
    }
  }
}

/**
 * Called at the beginning of each render frame, before {@link QuadtreeTileProvider#showTileThisFrame}
 * @param {FrameState} frameState The frame state.
 */
GlobeSurfaceTileProvider.prototype.initialize = function (frameState) {
  // update each layer for texture reprojection.
  this._imageryLayers.queueReprojectionCommands(frameState);

  if (this._layerOrderChanged) {
    this._layerOrderChanged = false;

    // Sort the TileImagery instances in each tile by the layer index.
    this._quadtree.forEachLoadedTile(function (tile) {
      tile.data.imagery.sort(sortTileImageryByLayerIndex);
    });
  }

  // Add credits for terrain and imagery providers.
  updateCredits(this, frameState);

  const vertexArraysToDestroy = this._vertexArraysToDestroy;
  const length = vertexArraysToDestroy.length;
  for (let j = 0; j < length; ++j) {
    GlobeSurfaceTile._freeVertexArray(vertexArraysToDestroy[j]);
  }
  vertexArraysToDestroy.length = 0;
};

/**
 * Called at the beginning of the update cycle for each render frame, before {@link QuadtreeTileProvider#showTileThisFrame}
 * or any other functions.
 *
 * @param {FrameState} frameState The frame state.
 */
GlobeSurfaceTileProvider.prototype.beginUpdate = function (frameState) {
  const tilesToRenderByTextureCount = this._tilesToRenderByTextureCount;
  for (let i = 0, len = tilesToRenderByTextureCount.length; i < len; ++i) {
    const tiles = tilesToRenderByTextureCount[i];
    if (defined(tiles)) {
      tiles.length = 0;
    }
  }
  // update clipping planes
  const clippingPlanes = this._clippingPlanes;
  if (defined(clippingPlanes) && clippingPlanes.enabled) {
    clippingPlanes.update(frameState);
  }

  // update clipping polygons
  const clippingPolygons = this._clippingPolygons;
  if (defined(clippingPolygons) && clippingPolygons.enabled) {
    clippingPolygons.update(frameState);
    clippingPolygons.queueCommands(frameState);
  }

  this._usedDrawCommands = 0;

  this._hasLoadedTilesThisFrame = false;
  this._hasFillTilesThisFrame = false;
};

/**
 * Called at the end of the update cycle for each render frame, after {@link QuadtreeTileProvider#showTileThisFrame}
 * and any other functions.
 *
 * @param {FrameState} frameState The frame state.
 */
GlobeSurfaceTileProvider.prototype.endUpdate = function (frameState) {
  if (!defined(this._renderState)) {
    this._renderState = RenderState.fromCache({
      // Write color and depth
      cull: {
        enabled: true,
      },
      depthTest: {
        enabled: true,
        func: DepthFunction.LESS,
      },
    });

    this._blendRenderState = RenderState.fromCache({
      // Write color and depth
      cull: {
        enabled: true,
      },
      depthTest: {
        enabled: true,
        func: DepthFunction.LESS_OR_EQUAL,
      },
      blending: BlendingState.ALPHA_BLEND,
    });

    let rs = clone(this._renderState, true);
    rs.cull.enabled = false;
    this._disableCullingRenderState = RenderState.fromCache(rs);

    rs = clone(this._blendRenderState, true);
    rs.cull.enabled = false;
    this._disableCullingBlendRenderState = RenderState.fromCache(rs);
  }

  // If this frame has a mix of loaded and fill tiles, we need to propagate
  // loaded heights to the fill tiles.
  if (this._hasFillTilesThisFrame && this._hasLoadedTilesThisFrame) {
    TerrainFillMesh.updateFillTiles(
      this,
      this._quadtree._tilesToRender,
      frameState,
      this._vertexArraysToDestroy,
    );
  }

  // When vertical exaggeration changes, all of the loaded tiles need to generate
  // geodetic surface normals so they can scale properly when rendered.
  // When exaggeration is reset, geodetic surface normals are removed to decrease
  // memory usage. Some tiles might have been constructed with the correct
  // exaggeration already, so skip over them.

  // If the geodetic surface normals can't be created because the tile doesn't
  // have a mesh, keep checking until the tile does have a mesh. This can happen
  // if the tile's mesh starts construction in a worker thread right before the
  // exaggeration changes.

  const quadtree = this.quadtree;
  const exaggeration = frameState.verticalExaggeration;
  const exaggerationRelativeHeight =
    frameState.verticalExaggerationRelativeHeight;
  const exaggerationChanged =
    this._oldVerticalExaggeration !== exaggeration ||
    this._oldVerticalExaggerationRelativeHeight !== exaggerationRelativeHeight;

  // Keep track of the next time there is a change in exaggeration
  this._oldVerticalExaggeration = exaggeration;
  this._oldVerticalExaggerationRelativeHeight = exaggerationRelativeHeight;

  if (exaggerationChanged) {
    quadtree.forEachLoadedTile(function (tile) {
      const surfaceTile = tile.data;
      surfaceTile.updateExaggeration(tile, frameState, quadtree);
    });
  }

  // Add the tile render commands to the command list, sorted by texture count.
  const tilesToRenderByTextureCount = this._tilesToRenderByTextureCount;
  for (
    let textureCountIndex = 0,
      textureCountLength = tilesToRenderByTextureCount.length;
    textureCountIndex < textureCountLength;
    ++textureCountIndex
  ) {
    const tilesToRender = tilesToRenderByTextureCount[textureCountIndex];
    if (!defined(tilesToRender)) {
      continue;
    }

    for (
      let tileIndex = 0, tileLength = tilesToRender.length;
      tileIndex < tileLength;
      ++tileIndex
    ) {
      const tile = tilesToRender[tileIndex];
      const tileBoundingRegion = tile.data.tileBoundingRegion;
      addDrawCommandsForTile(this, tile, frameState);
      frameState.minimumTerrainHeight = Math.min(
        frameState.minimumTerrainHeight,
        tileBoundingRegion.minimumHeight,
      );
    }
  }
};

function pushCommand(command, frameState) {
  const globeTranslucencyState = frameState.globeTranslucencyState;
  if (globeTranslucencyState.translucent) {
    const isBlendCommand = command.renderState.blending.enabled;
    globeTranslucencyState.pushDerivedCommands(
      command,
      isBlendCommand,
      frameState,
    );
  } else {
    frameState.commandList.push(command);
  }
}

/**
 * Adds draw commands for tiles rendered in the previous frame for a pick pass.
 *
 * @param {FrameState} frameState The frame state.
 */
GlobeSurfaceTileProvider.prototype.updateForPick = function (frameState) {
  // Add the tile pick commands from the tiles drawn last frame.
  const drawCommands = this._drawCommands;
  for (let i = 0, length = this._usedDrawCommands; i < length; ++i) {
    pushCommand(drawCommands[i], frameState);
  }
};

/**
 * Cancels any imagery re-projections in the queue.
 */
GlobeSurfaceTileProvider.prototype.cancelReprojections = function () {
  this._imageryLayers.cancelReprojections();
};

/**
 * Gets the maximum geometric error allowed in a tile at a given level, in meters.
 *
 * @param {number} level The tile level for which to get the maximum geometric error.
 * @returns {number} The maximum geometric error in meters.
 */
GlobeSurfaceTileProvider.prototype.getLevelMaximumGeometricError = function (
  level,
) {
  if (!defined(this._terrainProvider)) {
    return 0;
  }

  return this._terrainProvider.getLevelMaximumGeometricError(level);
};

/**
 * Loads, or continues loading, a given tile.  This function will continue to be called
 * until {@link QuadtreeTile#state} is no longer {@link QuadtreeTileLoadState#LOADING}.
 *
 * @param {FrameState} frameState The frame state.
 * @param {QuadtreeTile} tile The tile to load.
 */
GlobeSurfaceTileProvider.prototype.loadTile = function (frameState, tile) {
  // We don't want to load imagery until we're certain that the terrain tiles are actually visible.
  // So if our bounding volume isn't accurate because it came from another tile, load terrain only
  // initially. If we load some terrain and suddenly have a more accurate bounding volume and the
  // tile is _still_ visible, give the tile a chance to load imagery immediately rather than
  // waiting for next frame.

  let surfaceTile = tile.data;
  let terrainOnly = true;
  let terrainStateBefore;
  if (defined(surfaceTile)) {
    terrainOnly =
      surfaceTile.boundingVolumeSourceTile !== tile ||
      tile._lastSelectionResult === TileSelectionResult.CULLED_BUT_NEEDED;
    terrainStateBefore = surfaceTile.terrainState;
  }

  GlobeSurfaceTile.processStateMachine(
    tile,
    frameState,
    this.terrainProvider,
    this._imageryLayers,
    this.quadtree,
    this._vertexArraysToDestroy,
    terrainOnly,
  );

  surfaceTile = tile.data;
  if (terrainOnly && terrainStateBefore !== tile.data.terrainState) {
    // Terrain state changed. If:
    // a) The tile is visible, and
    // b) The bounding volume is accurate (updated as a side effect of computing visibility)
    // Then we'll load imagery, too.
    if (
      this.computeTileVisibility(tile, frameState, this.quadtree.occluders) !==
        Visibility.NONE &&
      surfaceTile.boundingVolumeSourceTile === tile
    ) {
      terrainOnly = false;
      GlobeSurfaceTile.processStateMachine(
        tile,
        frameState,
        this.terrainProvider,
        this._imageryLayers,
        this.quadtree,
        this._vertexArraysToDestroy,
        terrainOnly,
      );
    }
  }
};

const boundingSphereScratch = new BoundingSphere();
const rectangleIntersectionScratch = new Rectangle();
const splitCartographicLimitRectangleScratch = new Rectangle();
const rectangleCenterScratch = new Cartographic();

// cartographicLimitRectangle may span the IDL, but tiles never will.
function clipRectangleAntimeridian(tileRectangle, cartographicLimitRectangle) {
  if (cartographicLimitRectangle.west < cartographicLimitRectangle.east) {
    return cartographicLimitRectangle;
  }
  const splitRectangle = Rectangle.clone(
    cartographicLimitRectangle,
    splitCartographicLimitRectangleScratch,
  );
  const tileCenter = Rectangle.center(tileRectangle, rectangleCenterScratch);
  if (tileCenter.longitude > 0.0) {
    splitRectangle.east = CesiumMath.PI;
  } else {
    splitRectangle.west = -CesiumMath.PI;
  }
  return splitRectangle;
}

function isUndergroundVisible(tileProvider, frameState) {
  if (frameState.cameraUnderground) {
    return true;
  }

  if (frameState.globeTranslucencyState.translucent) {
    return true;
  }

  if (tileProvider.backFaceCulling) {
    return false;
  }

  const clippingPlanes = tileProvider._clippingPlanes;
  if (defined(clippingPlanes) && clippingPlanes.enabled) {
    return true;
  }

  const clippingPolygons = tileProvider._clippingPolygons;
  if (defined(clippingPolygons) && clippingPolygons.enabled) {
    return true;
  }

  if (
    !Rectangle.equals(
      tileProvider.cartographicLimitRectangle,
      Rectangle.MAX_VALUE,
    )
  ) {
    return true;
  }

  return false;
}

/**
 * Determines the visibility of a given tile.  The tile may be fully visible, partially visible, or not
 * visible at all.  Tiles that are renderable and are at least partially visible will be shown by a call
 * to {@link GlobeSurfaceTileProvider#showTileThisFrame}.
 *
 * @param {QuadtreeTile} tile The tile instance.
 * @param {FrameState} frameState The state information about the current frame.
 * @param {QuadtreeOccluders} occluders The objects that may occlude this tile.
 *
 * @returns {Visibility} Visibility.NONE if the tile is not visible,
 *                       Visibility.PARTIAL if the tile is partially visible, or
 *                       Visibility.FULL if the tile is fully visible.
 */
GlobeSurfaceTileProvider.prototype.computeTileVisibility = function (
  tile,
  frameState,
  occluders,
) {
  const distance = this.computeDistanceToTile(tile, frameState);
  tile._distance = distance;

  const undergroundVisible = isUndergroundVisible(this, frameState);

  if (frameState.fog.enabled && !undergroundVisible) {
    if (CesiumMath.fog(distance, frameState.fog.density) >= 1.0) {
      // Tile is completely in fog so return that it is not visible.
      return Visibility.NONE;
    }
  }

  const surfaceTile = tile.data;
  const tileBoundingRegion = surfaceTile.tileBoundingRegion;

  if (surfaceTile.boundingVolumeSourceTile === undefined) {
    // We have no idea where this tile is, so let's just call it partially visible.
    return Visibility.PARTIAL;
  }

  const cullingVolume = frameState.cullingVolume;
  let boundingVolume = tileBoundingRegion.boundingVolume;

  if (!defined(boundingVolume)) {
    boundingVolume = tileBoundingRegion.boundingSphere;
  }

  // Check if the tile is outside the limit area in cartographic space
  surfaceTile.clippedByBoundaries = false;
  const clippedCartographicLimitRectangle = clipRectangleAntimeridian(
    tile.rectangle,
    this.cartographicLimitRectangle,
  );
  const areaLimitIntersection = Rectangle.simpleIntersection(
    clippedCartographicLimitRectangle,
    tile.rectangle,
    rectangleIntersectionScratch,
  );
  if (!defined(areaLimitIntersection)) {
    return Visibility.NONE;
  }
  if (!Rectangle.equals(areaLimitIntersection, tile.rectangle)) {
    surfaceTile.clippedByBoundaries = true;
  }

  if (frameState.mode !== SceneMode.SCENE3D) {
    boundingVolume = boundingSphereScratch;
    BoundingSphere.fromRectangleWithHeights2D(
      tile.rectangle,
      frameState.mapProjection,
      tileBoundingRegion.minimumHeight,
      tileBoundingRegion.maximumHeight,
      boundingVolume,
    );
    Cartesian3.fromElements(
      boundingVolume.center.z,
      boundingVolume.center.x,
      boundingVolume.center.y,
      boundingVolume.center,
    );

    if (
      frameState.mode === SceneMode.MORPHING &&
      defined(surfaceTile.renderedMesh)
    ) {
      boundingVolume = BoundingSphere.union(
        tileBoundingRegion.boundingSphere,
        boundingVolume,
        boundingVolume,
      );
    }
  }

  if (!defined(boundingVolume)) {
    return Visibility.PARTIAL;
  }

  const clippingPlanes = this._clippingPlanes;
  if (defined(clippingPlanes) && clippingPlanes.enabled) {
    const planeIntersection =
      clippingPlanes.computeIntersectionWithBoundingVolume(boundingVolume);
    tile.isClipped = planeIntersection !== Intersect.INSIDE;
    if (planeIntersection === Intersect.OUTSIDE) {
      return Visibility.NONE;
    }
  }

  const clippingPolygons = this._clippingPolygons;
  if (defined(clippingPolygons) && clippingPolygons.enabled) {
    const polygonIntersection =
      clippingPolygons.computeIntersectionWithBoundingVolume(
        tileBoundingRegion,
      );
    tile.isClipped = polygonIntersection !== Intersect.OUTSIDE;
    // Polygon clipping intersections are determined by outer rectangles, therefore we cannot
    // preemptively determine if a tile is completely clipped or not here.
  }

  let visibility;
  const intersection = cullingVolume.computeVisibility(boundingVolume);

  if (intersection === Intersect.OUTSIDE) {
    visibility = Visibility.NONE;
  } else if (intersection === Intersect.INTERSECTING) {
    visibility = Visibility.PARTIAL;
  } else if (intersection === Intersect.INSIDE) {
    visibility = Visibility.FULL;
  }

  if (visibility === Visibility.NONE) {
    return visibility;
  }

  const ortho3D =
    frameState.mode === SceneMode.SCENE3D &&
    frameState.camera.frustum instanceof OrthographicFrustum;
  if (
    frameState.mode === SceneMode.SCENE3D &&
    !ortho3D &&
    defined(occluders) &&
    !undergroundVisible
  ) {
    const occludeePointInScaledSpace = surfaceTile.occludeePointInScaledSpace;
    if (!defined(occludeePointInScaledSpace)) {
      return visibility;
    }

    if (
      occluders.ellipsoid.isScaledSpacePointVisiblePossiblyUnderEllipsoid(
        occludeePointInScaledSpace,
        tileBoundingRegion.minimumHeight,
      )
    ) {
      return visibility;
    }

    return Visibility.NONE;
  }

  return visibility;
};

/**
 * Determines if the given tile can be refined
 * @param {QuadtreeTile} tile The tile to check.
 * @returns {boolean} True if the tile can be refined, false if it cannot.
 */
GlobeSurfaceTileProvider.prototype.canRefine = function (tile) {
  // Only allow refinement it we know whether or not the children of this tile exist.
  // For a tileset with `availability`, we'll always be able to refine.
  // We can ask for availability of _any_ child tile because we only need to confirm
  // that we get a yes or no answer, it doesn't matter what the answer is.
  if (defined(tile.data.terrainData)) {
    return true;
  }
  const childAvailable = this.terrainProvider.getTileDataAvailable(
    tile.x * 2,
    tile.y * 2,
    tile.level + 1,
  );
  return childAvailable !== undefined;
};

const readyImageryScratch = [];
const canRenderTraversalStack = [];

/**
 * Determines if the given not-fully-loaded tile can be rendered without losing detail that
 * was present last frame as a result of rendering descendant tiles. This method will only be
 * called if this tile's descendants were rendered last frame. If the tile is fully loaded,
 * it is assumed that this method will return true and it will not be called.
 * @param {QuadtreeTile} tile The tile to check.
 * @returns {boolean} True if the tile can be rendered without losing detail.
 */
GlobeSurfaceTileProvider.prototype.canRenderWithoutLosingDetail = function (
  tile,
  frameState,
) {
  const surfaceTile = tile.data;

  const readyImagery = readyImageryScratch;
  readyImagery.length = this._imageryLayers.length;

  let terrainReady = false;
  let initialImageryState = false;
  let imagery;

  if (defined(surfaceTile)) {
    // We can render even with non-ready terrain as long as all our rendered descendants
    // are missing terrain geometry too. i.e. if we rendered fills for more detailed tiles
    // last frame, it's ok to render a fill for this tile this frame.
    terrainReady = surfaceTile.terrainState === TerrainState.READY;

    // Initially assume all imagery layers are ready, unless imagery hasn't been initialized at all.
    initialImageryState = true;

    imagery = surfaceTile.imagery;
  }

  let i;
  let len;

  for (i = 0, len = readyImagery.length; i < len; ++i) {
    readyImagery[i] = initialImageryState;
  }

  if (defined(imagery)) {
    for (i = 0, len = imagery.length; i < len; ++i) {
      const tileImagery = imagery[i];
      const loadingImagery = tileImagery.loadingImagery;
      const isReady =
        !defined(loadingImagery) ||
        loadingImagery.state === ImageryState.FAILED ||
        loadingImagery.state === ImageryState.INVALID;
      const layerIndex = (
        tileImagery.loadingImagery || tileImagery.readyImagery
      ).imageryLayer._layerIndex;

      // For a layer to be ready, all tiles belonging to that layer must be ready.
      readyImagery[layerIndex] = isReady && readyImagery[layerIndex];
    }
  }

  const lastFrame = this.quadtree._lastSelectionFrameNumber;

  // Traverse the descendants looking for one with terrain or imagery that is not loaded on this tile.
  const stack = canRenderTraversalStack;
  stack.length = 0;
  stack.push(
    tile.southwestChild,
    tile.southeastChild,
    tile.northwestChild,
    tile.northeastChild,
  );

  while (stack.length > 0) {
    const descendant = stack.pop();
    const lastFrameSelectionResult =
      descendant._lastSelectionResultFrame === lastFrame
        ? descendant._lastSelectionResult
        : TileSelectionResult.NONE;

    if (lastFrameSelectionResult === TileSelectionResult.RENDERED) {
      const descendantSurface = descendant.data;

      if (!defined(descendantSurface)) {
        // Descendant has no data, so it can't block rendering.
        continue;
      }

      if (
        !terrainReady &&
        descendant.data.terrainState === TerrainState.READY
      ) {
        // Rendered descendant has real terrain, but we don't. Rendering is blocked.
        return false;
      }

      const descendantImagery = descendant.data.imagery;
      for (i = 0, len = descendantImagery.length; i < len; ++i) {
        const descendantTileImagery = descendantImagery[i];
        const descendantLoadingImagery = descendantTileImagery.loadingImagery;
        const descendantIsReady =
          !defined(descendantLoadingImagery) ||
          descendantLoadingImagery.state === ImageryState.FAILED ||
          descendantLoadingImagery.state === ImageryState.INVALID;
        const descendantLayerIndex = (
          descendantTileImagery.loadingImagery ||
          descendantTileImagery.readyImagery
        ).imageryLayer._layerIndex;

        // If this imagery tile of a descendant is ready but the layer isn't ready in this tile,
        // then rendering is blocked.
        if (descendantIsReady && !readyImagery[descendantLayerIndex]) {
          return false;
        }
      }
    } else if (lastFrameSelectionResult === TileSelectionResult.REFINED) {
      stack.push(
        descendant.southwestChild,
        descendant.southeastChild,
        descendant.northwestChild,
        descendant.northeastChild,
      );
    }
  }

  return true;
};

const tileDirectionScratch = new Cartesian3();

/**
 * Determines the priority for loading this tile. Lower priority values load sooner.
 * @param {QuadtreeTile} tile The tile.
 * @param {FrameState} frameState The frame state.
 * @returns {number} The load priority value.
 */
GlobeSurfaceTileProvider.prototype.computeTileLoadPriority = function (
  tile,
  frameState,
) {
  const surfaceTile = tile.data;
  if (surfaceTile === undefined) {
    return 0.0;
  }

  const obb = surfaceTile.tileBoundingRegion.boundingVolume;
  if (obb === undefined) {
    return 0.0;
  }

  const cameraPosition = frameState.camera.positionWC;
  const cameraDirection = frameState.camera.directionWC;
  const tileDirection = Cartesian3.subtract(
    obb.center,
    cameraPosition,
    tileDirectionScratch,
  );
  const magnitude = Cartesian3.magnitude(tileDirection);
  if (magnitude < CesiumMath.EPSILON5) {
    return 0.0;
  }
  Cartesian3.divideByScalar(tileDirection, magnitude, tileDirection);
  return (
    (1.0 - Cartesian3.dot(tileDirection, cameraDirection)) * tile._distance
  );
};

const modifiedModelViewScratch = new Matrix4();
const modifiedModelViewProjectionScratch = new Matrix4();
const tileRectangleScratch = new Cartesian4();
const localizedCartographicLimitRectangleScratch = new Cartesian4();
const localizedTranslucencyRectangleScratch = new Cartesian4();
const rtcScratch = new Cartesian3();
const centerEyeScratch = new Cartesian3();
const southwestScratch = new Cartesian3();
const northeastScratch = new Cartesian3();

/**
 * Shows a specified tile in this frame.  The provider can cause the tile to be shown by adding
 * render commands to the commandList, or use any other method as appropriate.  The tile is not
 * expected to be visible next frame as well, unless this method is called next frame, too.
 *
 * @param {QuadtreeTile} tile The tile instance.
 * @param {FrameState} frameState The state information of the current rendering frame.
 */
GlobeSurfaceTileProvider.prototype.showTileThisFrame = function (
  tile,
  frameState,
) {
  let readyTextureCount = 0;
  const tileImageryCollection = tile.data.imagery;
  for (let i = 0, len = tileImageryCollection.length; i < len; ++i) {
    const tileImagery = tileImageryCollection[i];
    if (
      defined(tileImagery.readyImagery) &&
      tileImagery.readyImagery.imageryLayer.alpha !== 0.0
    ) {
      ++readyTextureCount;
    }
  }

  let tileSet = this._tilesToRenderByTextureCount[readyTextureCount];
  if (!defined(tileSet)) {
    tileSet = [];
    this._tilesToRenderByTextureCount[readyTextureCount] = tileSet;
  }

  tileSet.push(tile);

  const surfaceTile = tile.data;
  if (!defined(surfaceTile.vertexArray)) {
    this._hasFillTilesThisFrame = true;
  } else {
    this._hasLoadedTilesThisFrame = true;
  }

  const debug = this._debug;
  ++debug.tilesRendered;
  debug.texturesRendered += readyTextureCount;
};

const cornerPositionsScratch = [
  new Cartesian3(),
  new Cartesian3(),
  new Cartesian3(),
  new Cartesian3(),
];

function computeOccludeePoint(
  tileProvider,
  center,
  rectangle,
  minimumHeight,
  maximumHeight,
  result,
) {
  const ellipsoidalOccluder = tileProvider.quadtree._occluders.ellipsoid;
  const ellipsoid = ellipsoidalOccluder.ellipsoid;

  const cornerPositions = cornerPositionsScratch;
  Cartesian3.fromRadians(
    rectangle.west,
    rectangle.south,
    maximumHeight,
    ellipsoid,
    cornerPositions[0],
  );
  Cartesian3.fromRadians(
    rectangle.east,
    rectangle.south,
    maximumHeight,
    ellipsoid,
    cornerPositions[1],
  );
  Cartesian3.fromRadians(
    rectangle.west,
    rectangle.north,
    maximumHeight,
    ellipsoid,
    cornerPositions[2],
  );
  Cartesian3.fromRadians(
    rectangle.east,
    rectangle.north,
    maximumHeight,
    ellipsoid,
    cornerPositions[3],
  );

  return ellipsoidalOccluder.computeHorizonCullingPointPossiblyUnderEllipsoid(
    center,
    cornerPositions,
    minimumHeight,
    result,
  );
}

/**
 * Gets the distance from the camera to the closest point on the tile.  This is used for level-of-detail selection.
 *
 * @param {QuadtreeTile} tile The tile instance.
 * @param {FrameState} frameState The state information of the current rendering frame.
 *
 * @returns {number} The distance from the camera to the closest point on the tile, in meters.
 */
GlobeSurfaceTileProvider.prototype.computeDistanceToTile = function (
  tile,
  frameState,
) {
  // The distance should be:
  // 1. the actual distance to the tight-fitting bounding volume, or
  // 2. a distance that is equal to or greater than the actual distance to the tight-fitting bounding volume.
  //
  // When we don't know the min/max heights for a tile, but we do know the min/max of an ancestor tile, we can
  // build a tight-fitting bounding volume horizontally, but not vertically. The min/max heights from the
  // ancestor will likely form a volume that is much bigger than it needs to be. This means that the volume may
  // be deemed to be much closer to the camera than it really is, causing us to select tiles that are too detailed.
  // Loading too-detailed tiles is super expensive, so we don't want to do that. We don't know where the child
  // tile really lies within the parent range of heights, but we _do_ know the child tile can't be any closer than
  // the ancestor height surface (min or max) that is _farthest away_ from the camera. So if we compute distance
  // based on that conservative metric, we may end up loading tiles that are not detailed enough, but that's much
  // better (faster) than loading tiles that are too detailed.

  updateTileBoundingRegion(tile, this, frameState);

  const surfaceTile = tile.data;
  const boundingVolumeSourceTile = surfaceTile.boundingVolumeSourceTile;
  if (boundingVolumeSourceTile === undefined) {
    // Can't find any min/max heights anywhere? Ok, let's just say the
    // tile is really far away so we'll load and render it rather than
    // refining.
    return 9999999999.0;
  }

  const tileBoundingRegion = surfaceTile.tileBoundingRegion;
  const min = tileBoundingRegion.minimumHeight;
  const max = tileBoundingRegion.maximumHeight;

  if (surfaceTile.boundingVolumeSourceTile !== tile) {
    const cameraHeight = frameState.camera.positionCartographic.height;
    const distanceToMin = Math.abs(cameraHeight - min);
    const distanceToMax = Math.abs(cameraHeight - max);
    if (distanceToMin > distanceToMax) {
      tileBoundingRegion.minimumHeight = min;
      tileBoundingRegion.maximumHeight = min;
    } else {
      tileBoundingRegion.minimumHeight = max;
      tileBoundingRegion.maximumHeight = max;
    }
  }

  const result = tileBoundingRegion.distanceToCamera(frameState);

  tileBoundingRegion.minimumHeight = min;
  tileBoundingRegion.maximumHeight = max;

  return result;
};

function updateTileBoundingRegion(tile, tileProvider, frameState) {
  let surfaceTile = tile.data;
  if (surfaceTile === undefined) {
    surfaceTile = tile.data = new GlobeSurfaceTile();
  }

  const ellipsoid = tile.tilingScheme.ellipsoid;
  if (surfaceTile.tileBoundingRegion === undefined) {
    surfaceTile.tileBoundingRegion = new TileBoundingRegion({
      computeBoundingVolumes: false,
      rectangle: tile.rectangle,
      ellipsoid: ellipsoid,
      minimumHeight: 0.0,
      maximumHeight: 0.0,
    });
  }

  const tileBoundingRegion = surfaceTile.tileBoundingRegion;
  const oldMinimumHeight = tileBoundingRegion.minimumHeight;
  const oldMaximumHeight = tileBoundingRegion.maximumHeight;
  let hasBoundingVolumesFromMesh = false;
  let sourceTile = tile;

  // Get min and max heights from the mesh.
  // If the mesh is not available, get them from the terrain data.
  // If the terrain data is not available either, get them from an ancestor.
  // If none of the ancestors are available, then there are no min and max heights for this tile at this time.
  const mesh = surfaceTile.mesh;
  const terrainData = surfaceTile.terrainData;
  if (
    mesh !== undefined &&
    mesh.minimumHeight !== undefined &&
    mesh.maximumHeight !== undefined
  ) {
    tileBoundingRegion.minimumHeight = mesh.minimumHeight;
    tileBoundingRegion.maximumHeight = mesh.maximumHeight;
    hasBoundingVolumesFromMesh = true;
  } else if (
    terrainData !== undefined &&
    terrainData._minimumHeight !== undefined &&
    terrainData._maximumHeight !== undefined
  ) {
    tileBoundingRegion.minimumHeight = terrainData._minimumHeight;
    tileBoundingRegion.maximumHeight = terrainData._maximumHeight;
  } else {
    // No accurate min/max heights available, so we're stuck with min/max heights from an ancestor tile.
    tileBoundingRegion.minimumHeight = Number.NaN;
    tileBoundingRegion.maximumHeight = Number.NaN;

    let ancestorTile = tile.parent;
    while (ancestorTile !== undefined) {
      const ancestorSurfaceTile = ancestorTile.data;
      if (ancestorSurfaceTile !== undefined) {
        const ancestorMesh = ancestorSurfaceTile.mesh;
        const ancestorTerrainData = ancestorSurfaceTile.terrainData;
        if (
          ancestorMesh !== undefined &&
          ancestorMesh.minimumHeight !== undefined &&
          ancestorMesh.maximumHeight !== undefined
        ) {
          tileBoundingRegion.minimumHeight = ancestorMesh.minimumHeight;
          tileBoundingRegion.maximumHeight = ancestorMesh.maximumHeight;
          break;
        } else if (
          ancestorTerrainData !== undefined &&
          ancestorTerrainData._minimumHeight !== undefined &&
          ancestorTerrainData._maximumHeight !== undefined
        ) {
          tileBoundingRegion.minimumHeight = ancestorTerrainData._minimumHeight;
          tileBoundingRegion.maximumHeight = ancestorTerrainData._maximumHeight;
          break;
        }
      }
      ancestorTile = ancestorTile.parent;
    }
    sourceTile = ancestorTile;
  }

  // Update bounding regions from the min and max heights
  if (sourceTile !== undefined) {
    const exaggeration = frameState.verticalExaggeration;
    const exaggerationRelativeHeight =
      frameState.verticalExaggerationRelativeHeight;
    const hasExaggeration = exaggeration !== 1.0;
    if (hasExaggeration) {
      hasBoundingVolumesFromMesh = false;
      tileBoundingRegion.minimumHeight = VerticalExaggeration.getHeight(
        tileBoundingRegion.minimumHeight,
        exaggeration,
        exaggerationRelativeHeight,
      );
      tileBoundingRegion.maximumHeight = VerticalExaggeration.getHeight(
        tileBoundingRegion.maximumHeight,
        exaggeration,
        exaggerationRelativeHeight,
      );
    }

    if (hasBoundingVolumesFromMesh) {
      if (!surfaceTile.boundingVolumeIsFromMesh) {
        tileBoundingRegion._orientedBoundingBox = OrientedBoundingBox.clone(
          mesh.orientedBoundingBox,
          tileBoundingRegion._orientedBoundingBox,
        );
        tileBoundingRegion._boundingSphere = BoundingSphere.clone(
          mesh.boundingSphere3D,
          tileBoundingRegion._boundingSphere,
        );
        surfaceTile.occludeePointInScaledSpace = Cartesian3.clone(
          mesh.occludeePointInScaledSpace,
          surfaceTile.occludeePointInScaledSpace,
        );

        // If the occludee point is not defined, fallback to calculating it from the OBB
        if (!defined(surfaceTile.occludeePointInScaledSpace)) {
          surfaceTile.occludeePointInScaledSpace = computeOccludeePoint(
            tileProvider,
            tileBoundingRegion._orientedBoundingBox.center,
            tile.rectangle,
            tileBoundingRegion.minimumHeight,
            tileBoundingRegion.maximumHeight,
            surfaceTile.occludeePointInScaledSpace,
          );
        }
      }
    } else {
      const needsBounds =
        tileBoundingRegion._orientedBoundingBox === undefined ||
        tileBoundingRegion._boundingSphere === undefined;
      const heightChanged =
        tileBoundingRegion.minimumHeight !== oldMinimumHeight ||
        tileBoundingRegion.maximumHeight !== oldMaximumHeight;
      if (heightChanged || needsBounds) {
        // Bounding volumes need to be recomputed in some circumstances
        tileBoundingRegion.computeBoundingVolumes(ellipsoid);
        surfaceTile.occludeePointInScaledSpace = computeOccludeePoint(
          tileProvider,
          tileBoundingRegion._orientedBoundingBox.center,
          tile.rectangle,
          tileBoundingRegion.minimumHeight,
          tileBoundingRegion.maximumHeight,
          surfaceTile.occludeePointInScaledSpace,
        );
      }
    }
    surfaceTile.boundingVolumeSourceTile = sourceTile;
    surfaceTile.boundingVolumeIsFromMesh = hasBoundingVolumesFromMesh;
  } else {
    surfaceTile.boundingVolumeSourceTile = undefined;
    surfaceTile.boundingVolumeIsFromMesh = false;
  }
}

/**
 * Returns true if this object was destroyed; otherwise, false.
 * <br /><br />
 * If this object was destroyed, it should not be used; calling any function other than
 * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
 *
 * @returns {boolean} True if this object was destroyed; otherwise, false.
 *
 * @see GlobeSurfaceTileProvider#destroy
 */
GlobeSurfaceTileProvider.prototype.isDestroyed = function () {
  return false;
};

/**
 * Destroys the WebGL resources held by this object.  Destroying an object allows for deterministic
 * release of WebGL resources, instead of relying on the garbage collector to destroy this object.
 * <br /><br />
 * Once an object is destroyed, it should not be used; calling any function other than
 * <code>isDestroyed</code> will result in a {@link DeveloperError} exception.  Therefore,
 * assign the return value (<code>undefined</code>) to the object as done in the example.
 *
 * @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
 *
 *
 * @example
 * provider = provider && provider();
 *
 * @see GlobeSurfaceTileProvider#isDestroyed
 */
GlobeSurfaceTileProvider.prototype.destroy = function () {
  this._tileProvider = this._tileProvider && this._tileProvider.destroy();
  this._clippingPlanes = this._clippingPlanes && this._clippingPlanes.destroy();
  this._clippingPolygons =
    this._clippingPolygons && this._clippingPolygons.destroy();
  this._removeLayerAddedListener =
    this._removeLayerAddedListener && this._removeLayerAddedListener();
  this._removeLayerRemovedListener =
    this._removeLayerRemovedListener && this._removeLayerRemovedListener();
  this._removeLayerMovedListener =
    this._removeLayerMovedListener && this._removeLayerMovedListener();
  this._removeLayerShownListener =
    this._removeLayerShownListener && this._removeLayerShownListener();

  return destroyObject(this);
};

function getTileReadyCallback(tileImageriesToFree, layer, terrainProvider) {
  return function (tile) {
    let tileImagery;
    let imagery;
    let startIndex = -1;
    const tileImageryCollection = tile.data.imagery;
    const length = tileImageryCollection.length;
    let i;
    for (i = 0; i < length; ++i) {
      tileImagery = tileImageryCollection[i];
      imagery = tileImagery.readyImagery ?? tileImagery.loadingImagery;
      if (imagery.imageryLayer === layer) {
        startIndex = i;
        break;
      }
    }

    if (startIndex !== -1) {
      const endIndex = startIndex + tileImageriesToFree;
      tileImagery = tileImageryCollection[endIndex];
      imagery = defined(tileImagery)
        ? (tileImagery.readyImagery ?? tileImagery.loadingImagery)
        : undefined;
      if (!defined(imagery) || imagery.imageryLayer !== layer) {
        // Return false to keep the callback if we have to wait on the skeletons
        // Return true to remove the callback if something went wrong
        return !layer._createTileImagerySkeletons(
          tile,
          terrainProvider,
          endIndex,
        );
      }

      for (i = startIndex; i < endIndex; ++i) {
        tileImageryCollection[i].freeResources();
      }

      tileImageryCollection.splice(startIndex, tileImageriesToFree);
    }

    return true; // Everything is done, so remove the callback
  };
}

GlobeSurfaceTileProvider.prototype._onLayerAdded = function (layer, index) {
  if (this.isDestroyed()) {
    return;
  }

  if (layer.show) {
    const terrainProvider = this._terrainProvider;

    const that = this;
    const tileImageryUpdatedEvent = this._imageryLayersUpdatedEvent;
    const reloadFunction = function () {
      // Clear the layer's cache
      layer._imageryCache = {};

      that._quadtree.forEachLoadedTile(function (tile)