/
TerrainProvider.js
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/
TerrainProvider.js
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import defined from './defined.js';
import defineProperties from './defineProperties.js';
import DeveloperError from './DeveloperError.js';
import IndexDatatype from './IndexDatatype.js';
import CesiumMath from './Math.js';
/**
* Provides terrain or other geometry for the surface of an ellipsoid. The surface geometry is
* organized into a pyramid of tiles according to a {@link TilingScheme}. This type describes an
* interface and is not intended to be instantiated directly.
*
* @alias TerrainProvider
* @constructor
*
* @see EllipsoidTerrainProvider
* @see CesiumTerrainProvider
* @see VRTheWorldTerrainProvider
* @see GoogleEarthEnterpriseTerrainProvider
*/
function TerrainProvider() {
DeveloperError.throwInstantiationError();
}
defineProperties(TerrainProvider.prototype, {
/**
* Gets an event that is raised when the terrain provider encounters an asynchronous error.. By subscribing
* to the event, you will be notified of the error and can potentially recover from it. Event listeners
* are passed an instance of {@link TileProviderError}.
* @memberof TerrainProvider.prototype
* @type {Event}
*/
errorEvent : {
get : DeveloperError.throwInstantiationError
},
/**
* Gets the credit to display when this terrain provider is active. Typically this is used to credit
* the source of the terrain. This function should
* not be called before {@link TerrainProvider#ready} returns true.
* @memberof TerrainProvider.prototype
* @type {Credit}
*/
credit : {
get : DeveloperError.throwInstantiationError
},
/**
* Gets the tiling scheme used by the provider. This function should
* not be called before {@link TerrainProvider#ready} returns true.
* @memberof TerrainProvider.prototype
* @type {TilingScheme}
*/
tilingScheme : {
get : DeveloperError.throwInstantiationError
},
/**
* Gets a value indicating whether or not the provider is ready for use.
* @memberof TerrainProvider.prototype
* @type {Boolean}
*/
ready : {
get : DeveloperError.throwInstantiationError
},
/**
* Gets a promise that resolves to true when the provider is ready for use.
* @memberof TerrainProvider.prototype
* @type {Promise.<Boolean>}
* @readonly
*/
readyPromise : {
get : DeveloperError.throwInstantiationError
},
/**
* Gets a value indicating whether or not the provider includes a water mask. The water mask
* indicates which areas of the globe are water rather than land, so they can be rendered
* as a reflective surface with animated waves. This function should not be
* called before {@link TerrainProvider#ready} returns true.
* @memberof TerrainProvider.prototype
* @type {Boolean}
*/
hasWaterMask : {
get : DeveloperError.throwInstantiationError
},
/**
* Gets a value indicating whether or not the requested tiles include vertex normals.
* This function should not be called before {@link TerrainProvider#ready} returns true.
* @memberof TerrainProvider.prototype
* @type {Boolean}
*/
hasVertexNormals : {
get : DeveloperError.throwInstantiationError
},
/**
* Gets an object that can be used to determine availability of terrain from this provider, such as
* at points and in rectangles. This function should not be called before
* {@link TerrainProvider#ready} returns true. This property may be undefined if availability
* information is not available.
* @memberof TerrainProvider.prototype
* @type {TileAvailability}
*/
availability : {
get : DeveloperError.throwInstantiationError
}
});
var regularGridIndicesCache = [];
/**
* Gets a list of indices for a triangle mesh representing a regular grid. Calling
* this function multiple times with the same grid width and height returns the
* same list of indices. The total number of vertices must be less than or equal
* to 65536.
*
* @param {Number} width The number of vertices in the regular grid in the horizontal direction.
* @param {Number} height The number of vertices in the regular grid in the vertical direction.
* @returns {Uint16Array|Uint32Array} The list of indices. Uint16Array gets returned for 64KB or less and Uint32Array for 4GB or less.
*/
TerrainProvider.getRegularGridIndices = function(width, height) {
//>>includeStart('debug', pragmas.debug);
if (width * height >= CesiumMath.FOUR_GIGABYTES) {
throw new DeveloperError('The total number of vertices (width * height) must be less than 4,294,967,296.');
}
//>>includeEnd('debug');
var byWidth = regularGridIndicesCache[width];
if (!defined(byWidth)) {
regularGridIndicesCache[width] = byWidth = [];
}
var indices = byWidth[height];
if (!defined(indices)) {
if (width * height < CesiumMath.SIXTY_FOUR_KILOBYTES) {
indices = byWidth[height] = new Uint16Array((width - 1) * (height - 1) * 6);
} else {
indices = byWidth[height] = new Uint32Array((width - 1) * (height - 1) * 6);
}
addRegularGridIndices(width, height, indices, 0);
}
return indices;
};
var regularGridAndEdgeIndicesCache = [];
/**
* @private
*/
TerrainProvider.getRegularGridIndicesAndEdgeIndices = function(width, height) {
//>>includeStart('debug', pragmas.debug);
if (width * height >= CesiumMath.FOUR_GIGABYTES) {
throw new DeveloperError('The total number of vertices (width * height) must be less than 4,294,967,296.');
}
//>>includeEnd('debug');
var byWidth = regularGridAndEdgeIndicesCache[width];
if (!defined(byWidth)) {
regularGridAndEdgeIndicesCache[width] = byWidth = [];
}
var indicesAndEdges = byWidth[height];
if (!defined(indicesAndEdges)) {
var indices = TerrainProvider.getRegularGridIndices(width, height);
var edgeIndices = getEdgeIndices(width, height);
var westIndicesSouthToNorth = edgeIndices.westIndicesSouthToNorth;
var southIndicesEastToWest = edgeIndices.southIndicesEastToWest;
var eastIndicesNorthToSouth = edgeIndices.eastIndicesNorthToSouth;
var northIndicesWestToEast = edgeIndices.northIndicesWestToEast;
indicesAndEdges = byWidth[height] = {
indices : indices,
westIndicesSouthToNorth : westIndicesSouthToNorth,
southIndicesEastToWest : southIndicesEastToWest,
eastIndicesNorthToSouth : eastIndicesNorthToSouth,
northIndicesWestToEast : northIndicesWestToEast
};
}
return indicesAndEdges;
};
var regularGridAndSkirtAndEdgeIndicesCache = [];
/**
* @private
*/
TerrainProvider.getRegularGridAndSkirtIndicesAndEdgeIndices = function(width, height) {
//>>includeStart('debug', pragmas.debug);
if (width * height >= CesiumMath.FOUR_GIGABYTES) {
throw new DeveloperError('The total number of vertices (width * height) must be less than 4,294,967,296.');
}
//>>includeEnd('debug');
var byWidth = regularGridAndSkirtAndEdgeIndicesCache[width];
if (!defined(byWidth)) {
regularGridAndSkirtAndEdgeIndicesCache[width] = byWidth = [];
}
var indicesAndEdges = byWidth[height];
if (!defined(indicesAndEdges)) {
var gridVertexCount = width * height;
var gridIndexCount = (width - 1) * (height - 1) * 6;
var edgeVertexCount = width * 2 + height * 2;
var edgeIndexCount = Math.max(0, edgeVertexCount - 4) * 6;
var vertexCount = gridVertexCount + edgeVertexCount;
var indexCount = gridIndexCount + edgeIndexCount;
var edgeIndices = getEdgeIndices(width, height);
var westIndicesSouthToNorth = edgeIndices.westIndicesSouthToNorth;
var southIndicesEastToWest = edgeIndices.southIndicesEastToWest;
var eastIndicesNorthToSouth = edgeIndices.eastIndicesNorthToSouth;
var northIndicesWestToEast = edgeIndices.northIndicesWestToEast;
var indices = IndexDatatype.createTypedArray(vertexCount, indexCount);
addRegularGridIndices(width, height, indices, 0);
TerrainProvider.addSkirtIndices(westIndicesSouthToNorth, southIndicesEastToWest, eastIndicesNorthToSouth, northIndicesWestToEast, gridVertexCount, indices, gridIndexCount);
indicesAndEdges = byWidth[height] = {
indices : indices,
westIndicesSouthToNorth : westIndicesSouthToNorth,
southIndicesEastToWest : southIndicesEastToWest,
eastIndicesNorthToSouth : eastIndicesNorthToSouth,
northIndicesWestToEast : northIndicesWestToEast,
indexCountWithoutSkirts : gridIndexCount
};
}
return indicesAndEdges;
};
/**
* @private
*/
TerrainProvider.addSkirtIndices = function(westIndicesSouthToNorth, southIndicesEastToWest, eastIndicesNorthToSouth, northIndicesWestToEast, vertexCount, indices, offset) {
var vertexIndex = vertexCount;
offset = addSkirtIndices(westIndicesSouthToNorth, vertexIndex, indices, offset);
vertexIndex += westIndicesSouthToNorth.length;
offset = addSkirtIndices(southIndicesEastToWest, vertexIndex, indices, offset);
vertexIndex += southIndicesEastToWest.length;
offset = addSkirtIndices(eastIndicesNorthToSouth, vertexIndex, indices, offset);
vertexIndex += eastIndicesNorthToSouth.length;
addSkirtIndices(northIndicesWestToEast, vertexIndex, indices, offset);
};
function getEdgeIndices(width, height) {
var westIndicesSouthToNorth = new Array(height);
var southIndicesEastToWest = new Array(width);
var eastIndicesNorthToSouth = new Array(height);
var northIndicesWestToEast = new Array(width);
var i;
for (i = 0; i < width; ++i) {
northIndicesWestToEast[i] = i;
southIndicesEastToWest[i] = width * height - 1 - i;
}
for (i = 0; i < height; ++i) {
eastIndicesNorthToSouth[i] = (i + 1) * width - 1;
westIndicesSouthToNorth[i] = (height - i - 1) * width;
}
return {
westIndicesSouthToNorth : westIndicesSouthToNorth,
southIndicesEastToWest : southIndicesEastToWest,
eastIndicesNorthToSouth : eastIndicesNorthToSouth,
northIndicesWestToEast : northIndicesWestToEast
};
}
function addRegularGridIndices(width, height, indices, offset) {
var index = 0;
for (var j = 0; j < height - 1; ++j) {
for (var i = 0; i < width - 1; ++i) {
var upperLeft = index;
var lowerLeft = upperLeft + width;
var lowerRight = lowerLeft + 1;
var upperRight = upperLeft + 1;
indices[offset++] = upperLeft;
indices[offset++] = lowerLeft;
indices[offset++] = upperRight;
indices[offset++] = upperRight;
indices[offset++] = lowerLeft;
indices[offset++] = lowerRight;
++index;
}
++index;
}
}
function addSkirtIndices(edgeIndices, vertexIndex, indices, offset) {
var previousIndex = edgeIndices[0];
var length = edgeIndices.length;
for (var i = 1; i < length; ++i) {
var index = edgeIndices[i];
indices[offset++] = previousIndex;
indices[offset++] = index;
indices[offset++] = vertexIndex;
indices[offset++] = vertexIndex;
indices[offset++] = index;
indices[offset++] = vertexIndex + 1;
previousIndex = index;
++vertexIndex;
}
return offset;
}
/**
* Specifies the quality of terrain created from heightmaps. A value of 1.0 will
* ensure that adjacent heightmap vertices are separated by no more than
* {@link Globe.maximumScreenSpaceError} screen pixels and will probably go very slowly.
* A value of 0.5 will cut the estimated level zero geometric error in half, allowing twice the
* screen pixels between adjacent heightmap vertices and thus rendering more quickly.
* @type {Number}
*/
TerrainProvider.heightmapTerrainQuality = 0.25;
/**
* Determines an appropriate geometric error estimate when the geometry comes from a heightmap.
*
* @param {Ellipsoid} ellipsoid The ellipsoid to which the terrain is attached.
* @param {Number} tileImageWidth The width, in pixels, of the heightmap associated with a single tile.
* @param {Number} numberOfTilesAtLevelZero The number of tiles in the horizontal direction at tile level zero.
* @returns {Number} An estimated geometric error.
*/
TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap = function(ellipsoid, tileImageWidth, numberOfTilesAtLevelZero) {
return ellipsoid.maximumRadius * 2 * Math.PI * TerrainProvider.heightmapTerrainQuality / (tileImageWidth * numberOfTilesAtLevelZero);
};
/**
* Requests the geometry for a given tile. This function should not be called before
* {@link TerrainProvider#ready} returns true. The result must include terrain data and
* may optionally include a water mask and an indication of which child tiles are available.
* @function
*
* @param {Number} x The X coordinate of the tile for which to request geometry.
* @param {Number} y The Y coordinate of the tile for which to request geometry.
* @param {Number} level The level of the tile for which to request geometry.
* @param {Request} [request] The request object. Intended for internal use only.
*
* @returns {Promise.<TerrainData>|undefined} A promise for the requested geometry. If this method
* returns undefined instead of a promise, it is an indication that too many requests are already
* pending and the request will be retried later.
*/
TerrainProvider.prototype.requestTileGeometry = DeveloperError.throwInstantiationError;
/**
* Gets the maximum geometric error allowed in a tile at a given level. This function should not be
* called before {@link TerrainProvider#ready} returns true.
* @function
*
* @param {Number} level The tile level for which to get the maximum geometric error.
* @returns {Number} The maximum geometric error.
*/
TerrainProvider.prototype.getLevelMaximumGeometricError = DeveloperError.throwInstantiationError;
/**
* Determines whether data for a tile is available to be loaded.
* @function
*
* @param {Number} x The X coordinate of the tile for which to request geometry.
* @param {Number} y The Y coordinate of the tile for which to request geometry.
* @param {Number} level The level of the tile for which to request geometry.
* @returns {Boolean} Undefined if not supported by the terrain provider, otherwise true or false.
*/
TerrainProvider.prototype.getTileDataAvailable = DeveloperError.throwInstantiationError;
/**
* Makes sure we load availability data for a tile
* @function
*
* @param {Number} x The X coordinate of the tile for which to request geometry.
* @param {Number} y The Y coordinate of the tile for which to request geometry.
* @param {Number} level The level of the tile for which to request geometry.
* @returns {undefined|Promise} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
*/
TerrainProvider.prototype.loadTileDataAvailability = DeveloperError.throwInstantiationError;
export default TerrainProvider;