242 lines
10 KiB
JavaScript
242 lines
10 KiB
JavaScript
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define([
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'./defined',
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'./defineProperties',
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'./DeveloperError',
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'./Math'
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], function(
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defined,
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defineProperties,
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DeveloperError,
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CesiumMath) {
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'use strict';
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/**
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* Provides terrain or other geometry for the surface of an ellipsoid. The surface geometry is
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* organized into a pyramid of tiles according to a {@link TilingScheme}. This type describes an
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* interface and is not intended to be instantiated directly.
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*
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* @alias TerrainProvider
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* @constructor
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*
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* @see EllipsoidTerrainProvider
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* @see CesiumTerrainProvider
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* @see VRTheWorldTerrainProvider
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* @see GoogleEarthEnterpriseTerrainProvider
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*/
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function TerrainProvider() {
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DeveloperError.throwInstantiationError();
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}
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defineProperties(TerrainProvider.prototype, {
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/**
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* Gets an event that is raised when the terrain provider encounters an asynchronous error.. By subscribing
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* to the event, you will be notified of the error and can potentially recover from it. Event listeners
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* are passed an instance of {@link TileProviderError}.
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* @memberof TerrainProvider.prototype
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* @type {Event}
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*/
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errorEvent : {
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get : DeveloperError.throwInstantiationError
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},
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/**
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* Gets the credit to display when this terrain provider is active. Typically this is used to credit
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* the source of the terrain. This function should
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* not be called before {@link TerrainProvider#ready} returns true.
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* @memberof TerrainProvider.prototype
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* @type {Credit}
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*/
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credit : {
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get : DeveloperError.throwInstantiationError
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},
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/**
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* Gets the tiling scheme used by the provider. This function should
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* not be called before {@link TerrainProvider#ready} returns true.
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* @memberof TerrainProvider.prototype
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* @type {TilingScheme}
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*/
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tilingScheme : {
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get : DeveloperError.throwInstantiationError
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},
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/**
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* Gets a value indicating whether or not the provider is ready for use.
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* @memberof TerrainProvider.prototype
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* @type {Boolean}
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*/
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ready : {
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get : DeveloperError.throwInstantiationError
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},
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/**
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* Gets a promise that resolves to true when the provider is ready for use.
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* @memberof TerrainProvider.prototype
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* @type {Promise.<Boolean>}
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* @readonly
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*/
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readyPromise : {
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get : DeveloperError.throwInstantiationError
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},
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/**
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* Gets a value indicating whether or not the provider includes a water mask. The water mask
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* indicates which areas of the globe are water rather than land, so they can be rendered
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* as a reflective surface with animated waves. This function should not be
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* called before {@link TerrainProvider#ready} returns true.
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* @memberof TerrainProvider.prototype
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* @type {Boolean}
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*/
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hasWaterMask : {
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get : DeveloperError.throwInstantiationError
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},
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/**
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* Gets a value indicating whether or not the requested tiles include vertex normals.
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* This function should not be called before {@link TerrainProvider#ready} returns true.
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* @memberof TerrainProvider.prototype
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* @type {Boolean}
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*/
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hasVertexNormals : {
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get : DeveloperError.throwInstantiationError
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},
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/**
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* Gets an object that can be used to determine availability of terrain from this provider, such as
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* at points and in rectangles. This function should not be called before
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* {@link TerrainProvider#ready} returns true. This property may be undefined if availability
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* information is not available.
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* @memberof TerrainProvider.prototype
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* @type {TileAvailability}
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*/
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availability : {
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get : DeveloperError.throwInstantiationError
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}
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});
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var regularGridIndexArrays = [];
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/**
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* Gets a list of indices for a triangle mesh representing a regular grid. Calling
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* this function multiple times with the same grid width and height returns the
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* same list of indices. The total number of vertices must be less than or equal
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* to 65536.
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*
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* @param {Number} width The number of vertices in the regular grid in the horizontal direction.
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* @param {Number} height The number of vertices in the regular grid in the vertical direction.
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* @returns {Uint16Array} The list of indices.
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*/
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TerrainProvider.getRegularGridIndices = function(width, height) {
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//>>includeStart('debug', pragmas.debug);
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if (width * height >= CesiumMath.SIXTY_FOUR_KILOBYTES) {
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throw new DeveloperError('The total number of vertices (width * height) must be less than 65536.');
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}
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//>>includeEnd('debug');
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var byWidth = regularGridIndexArrays[width];
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if (!defined(byWidth)) {
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regularGridIndexArrays[width] = byWidth = [];
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}
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var indices = byWidth[height];
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if (!defined(indices)) {
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indices = byWidth[height] = new Uint16Array((width - 1) * (height - 1) * 6);
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var index = 0;
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var indicesIndex = 0;
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for (var j = 0; j < height - 1; ++j) {
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for (var i = 0; i < width - 1; ++i) {
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var upperLeft = index;
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var lowerLeft = upperLeft + width;
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var lowerRight = lowerLeft + 1;
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var upperRight = upperLeft + 1;
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indices[indicesIndex++] = upperLeft;
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indices[indicesIndex++] = lowerLeft;
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indices[indicesIndex++] = upperRight;
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indices[indicesIndex++] = upperRight;
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indices[indicesIndex++] = lowerLeft;
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indices[indicesIndex++] = lowerRight;
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++index;
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}
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++index;
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}
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}
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return indices;
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};
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/**
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* Specifies the quality of terrain created from heightmaps. A value of 1.0 will
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* ensure that adjacent heightmap vertices are separated by no more than
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* {@link Globe.maximumScreenSpaceError} screen pixels and will probably go very slowly.
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* A value of 0.5 will cut the estimated level zero geometric error in half, allowing twice the
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* screen pixels between adjacent heightmap vertices and thus rendering more quickly.
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* @type {Number}
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*/
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TerrainProvider.heightmapTerrainQuality = 0.25;
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/**
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* Determines an appropriate geometric error estimate when the geometry comes from a heightmap.
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*
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* @param {Ellipsoid} ellipsoid The ellipsoid to which the terrain is attached.
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* @param {Number} tileImageWidth The width, in pixels, of the heightmap associated with a single tile.
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* @param {Number} numberOfTilesAtLevelZero The number of tiles in the horizontal direction at tile level zero.
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* @returns {Number} An estimated geometric error.
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*/
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TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap = function(ellipsoid, tileImageWidth, numberOfTilesAtLevelZero) {
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return ellipsoid.maximumRadius * 2 * Math.PI * TerrainProvider.heightmapTerrainQuality / (tileImageWidth * numberOfTilesAtLevelZero);
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};
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/**
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* Requests the geometry for a given tile. This function should not be called before
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* {@link TerrainProvider#ready} returns true. The result must include terrain data and
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* may optionally include a water mask and an indication of which child tiles are available.
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* @function
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*
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* @param {Number} x The X coordinate of the tile for which to request geometry.
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* @param {Number} y The Y coordinate of the tile for which to request geometry.
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* @param {Number} level The level of the tile for which to request geometry.
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* @param {Request} [request] The request object. Intended for internal use only.
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*
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* @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry. If this method
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* returns undefined instead of a promise, it is an indication that too many requests are already
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* pending and the request will be retried later.
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*/
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TerrainProvider.prototype.requestTileGeometry = DeveloperError.throwInstantiationError;
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/**
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* Gets the maximum geometric error allowed in a tile at a given level. This function should not be
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* called before {@link TerrainProvider#ready} returns true.
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* @function
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*
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* @param {Number} level The tile level for which to get the maximum geometric error.
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* @returns {Number} The maximum geometric error.
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*/
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TerrainProvider.prototype.getLevelMaximumGeometricError = DeveloperError.throwInstantiationError;
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/**
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* Determines whether data for a tile is available to be loaded.
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* @function
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*
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* @param {Number} x The X coordinate of the tile for which to request geometry.
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* @param {Number} y The Y coordinate of the tile for which to request geometry.
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* @param {Number} level The level of the tile for which to request geometry.
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* @returns {Boolean} Undefined if not supported by the terrain provider, otherwise true or false.
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*/
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TerrainProvider.prototype.getTileDataAvailable = DeveloperError.throwInstantiationError;
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/**
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* Makes sure we load availability data for a tile
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*
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* @param {Number} x The X coordinate of the tile for which to request geometry.
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* @param {Number} y The Y coordinate of the tile for which to request geometry.
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* @param {Number} level The level of the tile for which to request geometry.
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* @returns {undefined|Promise} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
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*/
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TerrainProvider.prototype.loadTileDataAvailability = DeveloperError.throwInstantiationError;
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return TerrainProvider;
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});
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