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Merge pull request #6617 from AnalyticalGraphicsInc/approximate-terra…
…in-heights Separate out approximate terrain heights function from GroundPrimitive
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,203 @@ | ||
| define([ | ||
| './buildModuleUrl', | ||
| './defaultValue', | ||
| './defined', | ||
| './BoundingSphere', | ||
| './Cartesian2', | ||
| './Cartesian3', | ||
| './Cartographic', | ||
| './Check', | ||
| './DeveloperError', | ||
| './Ellipsoid', | ||
| './GeographicTilingScheme', | ||
| './Rectangle', | ||
| './Resource' | ||
| ], function( | ||
| buildModuleUrl, | ||
| defaultValue, | ||
| defined, | ||
| BoundingSphere, | ||
| Cartesian2, | ||
| Cartesian3, | ||
| Cartographic, | ||
| Check, | ||
| DeveloperError, | ||
| Ellipsoid, | ||
| GeographicTilingScheme, | ||
| Rectangle, | ||
| Resource) { | ||
| 'use strict'; | ||
|
|
||
| var scratchDiagonalCartesianNE = new Cartesian3(); | ||
| var scratchDiagonalCartesianSW = new Cartesian3(); | ||
| var scratchDiagonalCartographic = new Cartographic(); | ||
| var scratchCenterCartesian = new Cartesian3(); | ||
| var scratchSurfaceCartesian = new Cartesian3(); | ||
|
|
||
| var scratchBoundingSphere = new BoundingSphere(); | ||
| var tilingScheme = new GeographicTilingScheme(); | ||
| var scratchCorners = [new Cartographic(), new Cartographic(), new Cartographic(), new Cartographic()]; | ||
| var scratchTileXY = new Cartesian2(); | ||
|
|
||
| /** | ||
| * A collection of functions for approximating terrain height | ||
| * @private | ||
| */ | ||
| var ApproximateTerrainHeights = {}; | ||
|
|
||
| /** | ||
| * Initializes the minimum and maximum terrain heights | ||
| * @return {Promise} | ||
| */ | ||
| ApproximateTerrainHeights.initialize = function() { | ||
| var initPromise = ApproximateTerrainHeights._initPromise; | ||
| if (defined(initPromise)) { | ||
| return initPromise; | ||
| } | ||
|
|
||
| ApproximateTerrainHeights._initPromise = Resource.fetchJson(buildModuleUrl('Assets/approximateTerrainHeights.json')).then(function(json) { | ||
| ApproximateTerrainHeights._terrainHeights = json; | ||
| }); | ||
|
|
||
| return ApproximateTerrainHeights._initPromise; | ||
| }; | ||
|
|
||
| /** | ||
| * Computes the minimum and maximum terrain heights for a given rectangle | ||
| * @param {Rectangle} rectangle THe bounding rectangle | ||
| * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid | ||
| * @return {{minimumTerrainHeight: Number, maximumTerrainHeight: Number}} | ||
| */ | ||
| ApproximateTerrainHeights.getApproximateTerrainHeights = function(rectangle, ellipsoid) { | ||
| //>>includeStart('debug', pragmas.debug); | ||
| Check.defined('rectangle', rectangle); | ||
| if (!defined(ApproximateTerrainHeights._terrainHeights)) { | ||
| throw new DeveloperError('You must call ApproximateTerrainHeights.initialize and wait for the promise to resolve before using this function'); | ||
| } | ||
| //>>includeEnd('debug'); | ||
| ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84); | ||
|
|
||
| var xyLevel = getTileXYLevel(rectangle); | ||
|
|
||
| // Get the terrain min/max for that tile | ||
| var minTerrainHeight = ApproximateTerrainHeights._defaultMinTerrainHeight; | ||
| var maxTerrainHeight = ApproximateTerrainHeights._defaultMaxTerrainHeight; | ||
| if (defined(xyLevel)) { | ||
| var key = xyLevel.level + '-' + xyLevel.x + '-' + xyLevel.y; | ||
| var heights = ApproximateTerrainHeights._terrainHeights[key]; | ||
| if (defined(heights)) { | ||
| minTerrainHeight = heights[0]; | ||
| maxTerrainHeight = heights[1]; | ||
| } | ||
|
|
||
| // Compute min by taking the center of the NE->SW diagonal and finding distance to the surface | ||
| ellipsoid.cartographicToCartesian(Rectangle.northeast(rectangle, scratchDiagonalCartographic), | ||
| scratchDiagonalCartesianNE); | ||
| ellipsoid.cartographicToCartesian(Rectangle.southwest(rectangle, scratchDiagonalCartographic), | ||
| scratchDiagonalCartesianSW); | ||
|
|
||
| Cartesian3.subtract(scratchDiagonalCartesianSW, scratchDiagonalCartesianNE, scratchCenterCartesian); | ||
| Cartesian3.add(scratchDiagonalCartesianNE, | ||
| Cartesian3.multiplyByScalar(scratchCenterCartesian, 0.5, scratchCenterCartesian), scratchCenterCartesian); | ||
| var surfacePosition = ellipsoid.scaleToGeodeticSurface(scratchCenterCartesian, scratchSurfaceCartesian); | ||
| if (defined(surfacePosition)) { | ||
| var distance = Cartesian3.distance(scratchCenterCartesian, surfacePosition); | ||
| minTerrainHeight = Math.min(minTerrainHeight, -distance); | ||
| } else { | ||
| minTerrainHeight = ApproximateTerrainHeights._defaultMinTerrainHeight; | ||
| } | ||
| } | ||
|
|
||
| minTerrainHeight = Math.max(ApproximateTerrainHeights._defaultMinTerrainHeight, minTerrainHeight); | ||
|
|
||
| return { | ||
| minimumTerrainHeight: minTerrainHeight, | ||
| maximumTerrainHeight: maxTerrainHeight | ||
| }; | ||
| }; | ||
|
|
||
| /** | ||
| * Computes the bounding sphere based on the tile heights in the rectangle | ||
| * @param {Rectangle} rectangle The bounding rectangle | ||
| * @param {Ellipsoid} [ellipsoid=Ellipsoid.WGS84] The ellipsoid | ||
| * @return {BoundingSphere} The result bounding sphere | ||
| */ | ||
| ApproximateTerrainHeights.getInstanceBoundingSphere = function(rectangle, ellipsoid) { | ||
| //>>includeStart('debug', pragmas.debug); | ||
| Check.defined('rectangle', rectangle); | ||
| if (!defined(ApproximateTerrainHeights._terrainHeights)) { | ||
| throw new DeveloperError('You must call ApproximateTerrainHeights.initialize and wait for the promise to resolve before using this function'); | ||
| } | ||
| //>>includeEnd('debug'); | ||
| ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84); | ||
|
|
||
| var xyLevel = getTileXYLevel(rectangle); | ||
|
|
||
| // Get the terrain max for that tile | ||
| var maxTerrainHeight = ApproximateTerrainHeights._defaultMaxTerrainHeight; | ||
| if (defined(xyLevel)) { | ||
| var key = xyLevel.level + '-' + xyLevel.x + '-' + xyLevel.y; | ||
| var heights = ApproximateTerrainHeights._terrainHeights[key]; | ||
| if (defined(heights)) { | ||
| maxTerrainHeight = heights[1]; | ||
| } | ||
| } | ||
|
|
||
| var result = BoundingSphere.fromRectangle3D(rectangle, ellipsoid, 0.0); | ||
| BoundingSphere.fromRectangle3D(rectangle, ellipsoid, maxTerrainHeight, scratchBoundingSphere); | ||
|
|
||
| return BoundingSphere.union(result, scratchBoundingSphere, result); | ||
| }; | ||
|
|
||
| function getTileXYLevel(rectangle) { | ||
| Cartographic.fromRadians(rectangle.east, rectangle.north, 0.0, scratchCorners[0]); | ||
| Cartographic.fromRadians(rectangle.west, rectangle.north, 0.0, scratchCorners[1]); | ||
| Cartographic.fromRadians(rectangle.east, rectangle.south, 0.0, scratchCorners[2]); | ||
| Cartographic.fromRadians(rectangle.west, rectangle.south, 0.0, scratchCorners[3]); | ||
|
|
||
| // Determine which tile the bounding rectangle is in | ||
| var lastLevelX = 0, lastLevelY = 0; | ||
| var currentX = 0, currentY = 0; | ||
| var maxLevel = ApproximateTerrainHeights._terrainHeightsMaxLevel; | ||
| var i; | ||
| for(i = 0; i <= maxLevel; ++i) { | ||
| var failed = false; | ||
| for(var j = 0; j < 4; ++j) { | ||
| var corner = scratchCorners[j]; | ||
| tilingScheme.positionToTileXY(corner, i, scratchTileXY); | ||
| if (j === 0) { | ||
| currentX = scratchTileXY.x; | ||
| currentY = scratchTileXY.y; | ||
| } else if(currentX !== scratchTileXY.x || currentY !== scratchTileXY.y) { | ||
| failed = true; | ||
| break; | ||
| } | ||
| } | ||
|
|
||
| if (failed) { | ||
| break; | ||
| } | ||
|
|
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| lastLevelX = currentX; | ||
| lastLevelY = currentY; | ||
| } | ||
|
|
||
| if (i === 0) { | ||
| return undefined; | ||
| } | ||
|
|
||
| return { | ||
| x : lastLevelX, | ||
| y : lastLevelY, | ||
| level : (i > maxLevel) ? maxLevel : (i - 1) | ||
| }; | ||
| } | ||
|
|
||
| ApproximateTerrainHeights._terrainHeightsMaxLevel = 6; | ||
| ApproximateTerrainHeights._defaultMaxTerrainHeight = 9000.0; | ||
| ApproximateTerrainHeights._defaultMinTerrainHeight = -100000.0; | ||
| ApproximateTerrainHeights._terrainHeights = undefined; | ||
| ApproximateTerrainHeights._initPromise = undefined; | ||
|
|
||
| return ApproximateTerrainHeights; | ||
| }); |
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