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CustomHeightmapTerrainProvider.js
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CustomHeightmapTerrainProvider.js
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import Check from "./Check.js";
import Credit from "./Credit.js";
import defaultValue from "./defaultValue.js";
import defined from "./defined.js";
import Ellipsoid from "./Ellipsoid.js";
import Event from "./Event.js";
import GeographicTilingScheme from "./GeographicTilingScheme.js";
import HeightmapTerrainData from "./HeightmapTerrainData.js";
import TerrainProvider from "./TerrainProvider.js";
/**
* @callback CustomHeightmapTerrainProvider.GeometryCallback
* @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 {Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array|Number[]|Promise.<Int8Array|Uint8Array|Int16Array|Uint16Array|Int32Array|Uint32Array|Float32Array|Float64Array|Number[]>|undefined} An array or a promise to an array of heights in row-major order. If undefined, the globe will render the parent tile.
*/
/**
* A simple {@link TerrainProvider} that gets height values from a callback function.
* It can be used for procedurally generated terrain or as a way to load custom
* heightmap data without creating a subclass of {@link TerrainProvider}.
*
* There are some limitations such as no water mask, no vertex normals, and no
* availability, so a full-fledged {@link TerrainProvider} subclass is better suited
* for these more sophisticated use cases.
*
* @alias CustomHeightmapTerrainProvider
* @constructor
*
* @param {Object} options Object with the following properties:
* @param {CustomHeightmapTerrainProvider.GeometryCallback} options.callback The callback function for requesting tile geometry.
* @param {Number} options.width The number of columns per heightmap tile.
* @param {Number} options.height The number of rows per heightmap tile.
* @param {TilingScheme} [options.tilingScheme] The tiling scheme specifying how the ellipsoidal
* surface is broken into tiles. If this parameter is not provided, a {@link GeographicTilingScheme}
* is used.
* @param {Ellipsoid} [options.ellipsoid] The ellipsoid. If the tilingScheme is specified,
* this parameter is ignored and the tiling scheme's ellipsoid is used instead. If neither
* parameter is specified, the WGS84 ellipsoid is used.
* @param {Credit|String} [options.credit] A credit for the data source, which is displayed on the canvas.
*
* @example
* const viewer = new Cesium.Viewer("cesiumContainer", {
* terrainProvider: new Cesium.CustomHeightmapTerrainProvider({
* width: 32,
* height: 32,
* callback: function (x, y, level) {
* return new Float32Array(32 * 32); // all zeros
* },
* }),
* });
*
* @see TerrainProvider
*/
function CustomHeightmapTerrainProvider(options) {
options = defaultValue(options, defaultValue.EMPTY_OBJECT);
//>>includeStart('debug', pragmas.debug);
Check.defined("options.callback", options.callback);
Check.defined("options.width", options.width);
Check.defined("options.height", options.height);
//>>includeEnd('debug');
this._callback = options.callback;
this._tilingScheme = options.tilingScheme;
if (!defined(this._tilingScheme)) {
this._tilingScheme = new GeographicTilingScheme({
ellipsoid: defaultValue(options.ellipsoid, Ellipsoid.WGS84),
});
}
this._width = options.width;
this._height = options.height;
const maxTileDimensions = Math.max(this._width, this._height);
this._levelZeroMaximumGeometricError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(
this._tilingScheme.ellipsoid,
maxTileDimensions,
this._tilingScheme.getNumberOfXTilesAtLevel(0)
);
this._errorEvent = new Event();
let credit = options.credit;
if (typeof credit === "string") {
credit = new Credit(credit);
}
this._credit = credit;
this._readyPromise = Promise.resolve(true);
}
Object.defineProperties(CustomHeightmapTerrainProvider.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 CustomHeightmapTerrainProvider.prototype
* @type {Event}
* @readonly
*/
errorEvent: {
get: function () {
return this._errorEvent;
},
},
/**
* Gets the credit to display when this terrain provider is active. Typically this is used to credit
* the source of the terrain.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {Credit}
* @readonly
*/
credit: {
get: function () {
return this._credit;
},
},
/**
* Gets the tiling scheme used by this provider.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {TilingScheme}
* @readonly
*/
tilingScheme: {
get: function () {
return this._tilingScheme;
},
},
/**
* Gets a value indicating whether or not the provider is ready for use.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {Boolean}
* @readonly
*/
ready: {
get: function () {
return true;
},
},
/**
* Gets a promise that resolves to true when the provider is ready for use.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {Promise.<Boolean>}
* @readonly
*/
readyPromise: {
get: function () {
return this._readyPromise;
},
},
/**
* 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.
* Water mask is not supported by {@link CustomHeightmapTerrainProvider}, so the return
* value will always be false.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {Boolean}
* @readonly
*/
hasWaterMask: {
get: function () {
return false;
},
},
/**
* Gets a value indicating whether or not the requested tiles include vertex normals.
* Vertex normals are not supported by {@link CustomHeightmapTerrainProvider}, so the return
* value will always be false.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {Boolean}
* @readonly
*/
hasVertexNormals: {
get: function () {
return false;
},
},
/**
* Gets the number of columns per heightmap tile.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {Boolean}
* @readonly
*/
width: {
get: function () {
return this._width;
},
},
/**
* Gets the number of rows per heightmap tile.
* @memberof CustomHeightmapTerrainProvider.prototype
* @type {Boolean}
* @readonly
*/
height: {
get: function () {
return this._height;
},
},
});
/**
* Requests the geometry for a given tile. The result includes terrain
* data and indicates that all child tiles are available.
*
* @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.
*/
CustomHeightmapTerrainProvider.prototype.requestTileGeometry = function (
x,
y,
level,
request
) {
const promise = this._callback(x, y, level);
if (!defined(promise)) {
return undefined;
}
const width = this._width;
const height = this._height;
return Promise.resolve(promise).then(function (heightmapData) {
let buffer = heightmapData;
if (Array.isArray(buffer)) {
// HeightmapTerrainData expects a TypedArray, so convert from Number[] to Float64Array
buffer = new Float64Array(buffer);
}
return new HeightmapTerrainData({
buffer: buffer,
width: width,
height: height,
});
});
};
/**
* Gets the maximum geometric error allowed in a tile at a given level.
*
* @param {Number} level The tile level for which to get the maximum geometric error.
* @returns {Number} The maximum geometric error.
*/
CustomHeightmapTerrainProvider.prototype.getLevelMaximumGeometricError = function (
level
) {
return this._levelZeroMaximumGeometricError / (1 << level);
};
/**
* Determines whether data for a tile is available to be loaded.
*
* @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} Undefined if not supported, otherwise true or false.
*/
CustomHeightmapTerrainProvider.prototype.getTileDataAvailable = function (
x,
y,
level
) {
return undefined;
};
/**
* Makes sure we load availability data for a tile
*
* @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<void>} Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded
*/
CustomHeightmapTerrainProvider.prototype.loadTileDataAvailability = function (
x,
y,
level
) {
return undefined;
};
export default CustomHeightmapTerrainProvider;