Merge pull request #3223 from AnalyticalGraphicsInc/issue3170

Resolve issue #3170

CHANGES.md

@@ -31,6 +31,7 @@ Change Log
 * Added `VideoSynchronizer` helper object for keeping an `HTMLVideoElement` in sync with a scene's clock.
 * Added 'Video' Sandcastle showcase to demonstrate video materials.
 * Added `createOpenStreetMapImageryProvider` function to replace the `OpenStreetMapImageryProvider` class. This function returns a constructed `UrlTemplateImageryProvider`.
+* Fixed an issue with tile selection when below the surface of the ellipsoid. [#3170](https://github.com/AnalyticalGraphicsInc/cesium/issues/3170)
 
 ### 1.15 - 2015-11-02
 

Source/Core/EllipsoidalOccluder.js

@@ -129,18 +129,15 @@ define([
      * occluder.isScaledSpacePointVisible(scaledSpacePoint); //returns true
      */
     EllipsoidalOccluder.prototype.isScaledSpacePointVisible = function(occludeeScaledSpacePosition) {
-        // Disable occlusion culling when the viewer is under the ellipsoid to avoid false occulsion.
-        if (this._distanceToLimbInScaledSpaceSquared < 0.0) {
-            return true;
-        }
-
         // See http://cesiumjs.org/2013/04/25/Horizon-culling/
         var cv = this._cameraPositionInScaledSpace;
         var vhMagnitudeSquared = this._distanceToLimbInScaledSpaceSquared;
         var vt = Cartesian3.subtract(occludeeScaledSpacePosition, cv, scratchCartesian);
         var vtDotVc = -Cartesian3.dot(vt, cv);
-        var isOccluded = vtDotVc > vhMagnitudeSquared &&
-                         vtDotVc * vtDotVc / Cartesian3.magnitudeSquared(vt) > vhMagnitudeSquared;
+        // If vhMagnitudeSquared < 0 then we are below the surface of the ellipsoid and
+        // in this case, set the culling plane to be on V.
+        var isOccluded = vhMagnitudeSquared < 0 ? vtDotVc > 0 : (vtDotVc > vhMagnitudeSquared &&
+                         vtDotVc * vtDotVc / Cartesian3.magnitudeSquared(vt) > vhMagnitudeSquared);
         return !isOccluded;
     };
 

Specs/Core/EllipsoidalOccluderSpec.js

@@ -58,6 +58,15 @@ defineSuite([
         expect(occluder.isPointVisible(point)).toEqual(false);
     });
 
+    it('reports not visible when point is directly behind ellipsoid and camera is inside the ellispoid', function() {
+        var ellipsoid = Ellipsoid.WGS84;
+        var occluder = new EllipsoidalOccluder(ellipsoid);
+        occluder.cameraPosition = new Cartesian3(ellipsoid.minimumRadius - 100, 0.0, 0.0);
+
+        var point = new Cartesian3(-7000000, 0.0, 0.0);
+        expect(occluder.isPointVisible(point)).toEqual(false);
+    });
+
     it('reports visible when point is in front of ellipsoid', function() {
         var ellipsoid = Ellipsoid.WGS84;
         var occluder = new EllipsoidalOccluder(ellipsoid);