/
VRTheWorldTerrainProvider.js
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/
VRTheWorldTerrainProvider.js
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/*global define*/
define([
'../Core/defaultValue',
'../Core/defined',
'../Core/loadImage',
'../Core/loadXML',
'../Core/getImagePixels',
'../Core/throttleRequestByServer',
'../Core/writeTextToCanvas',
'../Core/DeveloperError',
'../Core/Extent',
'../Core/Math',
'../Core/Ellipsoid',
'../Core/Event',
'./Credit',
'./TerrainProvider',
'./TileProviderError',
'./GeographicTilingScheme',
'./HeightmapTerrainData',
'../ThirdParty/when'
], function(
defaultValue,
defined,
loadImage,
loadXML,
getImagePixels,
throttleRequestByServer,
writeTextToCanvas,
DeveloperError,
Extent,
CesiumMath,
Ellipsoid,
Event,
Credit,
TerrainProvider,
TileProviderError,
GeographicTilingScheme,
HeightmapTerrainData,
when) {
"use strict";
function DataExtent(extent, maxLevel) {
this.extent = extent;
this.maxLevel = maxLevel;
}
/**
* A {@link TerrainProvider} that produces terrain geometry by tessellating height maps
* retrieved from a {@link http://vr-theworld.com/|VT MÄK VR-TheWorld server}.
*
* @alias VRTheWorldTerrainProvider
* @constructor
*
* @param {String} description.url The URL of the VR-TheWorld TileMap.
* @param {Object} [description.proxy] A proxy to use for requests. This object is expected to have a getURL function which returns the proxied URL, if needed.
* @param {Ellipsoid} [description.ellipsoid=Ellipsoid.WGS84] The ellipsoid. If this parameter is not
* specified, the WGS84 ellipsoid is used.
* @param {Credit|String} [description.credit] A credit for the data source, which is displayed on the canvas.
*
* @see TerrainProvider
*
* @example
* var terrainProvider = new VRTheWorldTerrainProvider({
* url : 'http://www.vr-theworld.com/vr-theworld/tiles1.0.0/73/'
* });
* centralBody.terrainProvider = terrainProvider;
*/
var VRTheWorldTerrainProvider = function VRTheWorldTerrainProvider(description) {
description = defaultValue(description, defaultValue.EMPTY_OBJECT);
if (!defined(description.url)) {
throw new DeveloperError('description.url is required.');
}
this._url = description.url;
if (this._url.length > 0 && this._url[this._url.length - 1] !== '/') {
this._url += '/';
}
this._errorEvent = new Event();
this._ready = false;
this._proxy = description.proxy;
this._terrainDataStructure = {
heightScale : 1.0 / 1000.0,
heightOffset : -1000.0,
elementsPerHeight : 3,
stride : 4,
elementMultiplier : 256.0,
isBigEndian : true
};
var credit = description.credit;
if (typeof credit === 'string') {
credit = new Credit(credit);
}
this._credit = credit;
this._tilingScheme = undefined;
this._extents = [];
var that = this;
var metadataError;
var ellipsoid = defaultValue(description.ellipsoid, Ellipsoid.WGS84);
function metadataSuccess(xml) {
var srs = xml.getElementsByTagName('SRS')[0].textContent;
if (srs === 'EPSG:4326') {
that._tilingScheme = new GeographicTilingScheme({ ellipsoid : ellipsoid });
} else {
metadataFailure('SRS ' + srs + ' is not supported.');
return;
}
var tileFormat = xml.getElementsByTagName('TileFormat')[0];
that._heightmapWidth = parseInt(tileFormat.getAttribute('width'), 10);
that._heightmapHeight = parseInt(tileFormat.getAttribute('height'), 10);
that._levelZeroMaximumGeometricError = TerrainProvider.getEstimatedLevelZeroGeometricErrorForAHeightmap(ellipsoid, Math.min(that._heightmapWidth, that._heightmapHeight), that._tilingScheme.getNumberOfXTilesAtLevel(0));
var dataExtents = xml.getElementsByTagName('DataExtent');
for (var i = 0; i < dataExtents.length; ++i) {
var dataExtent = dataExtents[i];
var west = CesiumMath.toRadians(parseFloat(dataExtent.getAttribute('minx')));
var south = CesiumMath.toRadians(parseFloat(dataExtent.getAttribute('miny')));
var east = CesiumMath.toRadians(parseFloat(dataExtent.getAttribute('maxx')));
var north = CesiumMath.toRadians(parseFloat(dataExtent.getAttribute('maxy')));
var maxLevel = parseInt(dataExtent.getAttribute('maxlevel'), 10);
that._extents.push(new DataExtent(new Extent(west, south, east, north), maxLevel));
}
that._ready = true;
}
function metadataFailure(e) {
var message = defaultValue(e, 'An error occurred while accessing ' + that._url + '.');
metadataError = TileProviderError.handleError(metadataError, that, that._errorEvent, message, undefined, undefined, undefined, requestMetadata);
}
function requestMetadata() {
when(loadXML(that._url), metadataSuccess, metadataFailure);
}
requestMetadata();
};
/**
* Requests the geometry for a given tile. This function should not be called before
* {@link ArcGisImageServerTerrainProvider#isReady} returns true. The result includes terrain
* data and indicates that all child tiles are available.
*
* @memberof VRTheWorldTerrainProvider
*
* @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 {Boolean} [throttleRequests=true] True if the number of simultaneous requests should be limited,
* or false if the request should be initiated regardless of the number of requests
* already in progress.
* @returns {Promise|TerrainData} 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.
*/
VRTheWorldTerrainProvider.prototype.requestTileGeometry = function(x, y, level, throttleRequests) {
if (!this.isReady()) {
throw new DeveloperError('requestTileGeometry must not be called before isReady returns true.');
}
var yTiles = this._tilingScheme.getNumberOfYTilesAtLevel(level);
var url = this._url + level + '/' + x + '/' + (yTiles - y - 1) + '.tif?cesium=true';
var proxy = this._proxy;
if (defined(proxy)) {
url = proxy.getURL(url);
}
var promise;
throttleRequests = defaultValue(throttleRequests, true);
if (throttleRequests) {
promise = throttleRequestByServer(url, loadImage);
if (!defined(promise)) {
return undefined;
}
} else {
promise = loadImage(url);
}
var that = this;
return when(promise, function(image) {
return new HeightmapTerrainData({
buffer : getImagePixels(image),
width : that._heightmapWidth,
height : that._heightmapHeight,
childTileMask : getChildMask(that, x, y, level),
structure : that._terrainDataStructure
});
});
};
/**
* 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 VRTheWorldTerrainProvider
*
* @returns {Event} The event.
*/
VRTheWorldTerrainProvider.prototype.getErrorEvent = function() {
return this._errorEvent;
};
/**
* Gets the maximum geometric error allowed in a tile at a given level.
*
* @memberof VRTheWorldTerrainProvider
*
* @param {Number} level The tile level for which to get the maximum geometric error.
* @returns {Number} The maximum geometric error.
*/
VRTheWorldTerrainProvider.prototype.getLevelMaximumGeometricError = function(level) {
if (!this.isReady()) {
throw new DeveloperError('requestTileGeometry must not be called before isReady returns true.');
}
return this._levelZeroMaximumGeometricError / (1 << level);
};
/**
* 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 ArcGisImageServerTerrainProvider#isReady} returns true.
*
* @memberof VRTheWorldTerrainProvider
*
* @returns {Credit} The credit, or undefined if no credit exists
*/
VRTheWorldTerrainProvider.prototype.getCredit = function() {
return this._credit;
};
/**
* Gets the tiling scheme used by this provider. This function should
* not be called before {@link ArcGisImageServerTerrainProvider#isReady} returns true.
*
* @memberof VRTheWorldTerrainProvider
*
* @returns {TilingScheme} The tiling scheme.
* @see WebMercatorTilingScheme
* @see GeographicTilingScheme
*
* @exception {DeveloperError} <code>getTilingScheme</code> must not be called before the terrain provider is ready.
*/
VRTheWorldTerrainProvider.prototype.getTilingScheme = function() {
if (!this.isReady()) {
throw new DeveloperError('requestTileGeometry must not be called before isReady returns true.');
}
return this._tilingScheme;
};
/**
* 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.
*
* @memberof VRTheWorldTerrainProvider
*
* @returns {Boolean} True if the provider has a water mask; otherwise, false.
*/
VRTheWorldTerrainProvider.prototype.hasWaterMask = function() {
return false;
};
/**
* Gets a value indicating whether or not the provider is ready for use.
*
* @memberof VRTheWorldTerrainProvider
*
* @returns {Boolean} True if the provider is ready to use; otherwise, false.
*/
VRTheWorldTerrainProvider.prototype.isReady = function() {
return this._ready;
};
var extentScratch = new Extent();
function getChildMask(provider, x, y, level) {
var tilingScheme = provider._tilingScheme;
var extents = provider._extents;
var parentExtent = tilingScheme.tileXYToExtent(x, y, level);
var childMask = 0;
for (var i = 0; i < extents.length && childMask !== 15; ++i) {
var extent = extents[i];
if (extent.maxLevel <= level) {
continue;
}
var testExtent = extent.extent;
var intersection = testExtent.intersectWith(parentExtent, extentScratch);
if (!intersection.isEmpty()) {
// Parent tile is inside this extent, so at least one child is, too.
if (isTileInExtent(tilingScheme, testExtent, x * 2, y * 2, level + 1)) {
childMask |= 4; // northwest
}
if (isTileInExtent(tilingScheme, testExtent, x * 2 + 1, y * 2, level + 1)) {
childMask |= 8; // northeast
}
if (isTileInExtent(tilingScheme, testExtent, x * 2, y * 2 + 1, level + 1)) {
childMask |= 1; // southwest
}
if (isTileInExtent(tilingScheme, testExtent, x * 2 + 1, y * 2 + 1, level + 1)) {
childMask |= 2; // southeast
}
}
}
return childMask;
}
function isTileInExtent(tilingScheme, extent, x, y, level) {
var tileExtent = tilingScheme.tileXYToExtent(x, y, level);
return !tileExtent.intersectWith(extent, extentScratch).isEmpty();
}
return VRTheWorldTerrainProvider;
});