Fix a bug in QuadtreePrimitive.forEachLoadedTile

CHANGES.md

@@ -14,6 +14,7 @@ a url to a glTF file.  [#2078](https://github.com/AnalyticalGraphicsInc/cesium/i
 * Added `TerrainProvider.getTileDataAvailable` to improve tile loading performance when camera starts near globe.
 * Added `Globe.showWaterEffect` to enable/disable the water effect for supported terrain providers.
 * Added `Globe.baseColor` to set the color of the globe when no imagery is available.
+* Fixed a bug that could crash a crash when quickly adding and removing imagery layers.
 
 ### 1.1 - 2014-09-02
 

Source/Scene/QuadtreePrimitive.js

@@ -9,6 +9,7 @@ define([
         '../Core/Visibility',
         './QuadtreeOccluders',
         './QuadtreeTile',
+        './QuadtreeTileLoadState',
         './SceneMode',
         './TileReplacementQueue'
     ], function(
@@ -21,6 +22,7 @@ define([
         Visibility,
         QuadtreeOccluders,
         QuadtreeTile,
+        QuadtreeTileLoadState,
         SceneMode,
         TileReplacementQueue) {
     "use strict";
@@ -159,7 +161,9 @@ define([
     QuadtreePrimitive.prototype.forEachLoadedTile = function(tileFunction) {
         var tile = this._tileReplacementQueue.head;
         while (defined(tile)) {
-            tileFunction(tile);
+            if (tile.state !== QuadtreeTileLoadState.START) {
+                tileFunction(tile);
+            }
             tile = tile.replacementNext;
         }
     };

Specs/Scene/QuadtreePrimitiveSpec.js

@@ -130,4 +130,34 @@ defineSuite([
         quadtree.update(context, frameState, []);
         expect(calls).toBe(2);
     });
+
+    it('forEachLoadedTile does not enumerate tiles in the START state', function() {
+        var tileProvider = createSpyTileProvider();
+        tileProvider.getReady.andReturn(true);
+        tileProvider.computeTileVisibility.andReturn(Visibility.FULL);
+        tileProvider.computeDistanceToTile.andReturn(1e-15);
+
+        // Load the root tiles.
+        tileProvider.loadTile.andCallFake(function(context, frameState, tile) {
+            tile.state = QuadtreeTileLoadState.DONE;
+            tile.renderable = true;
+        });
+
+        var quadtree = new QuadtreePrimitive({
+            tileProvider : tileProvider
+        });
+
+        quadtree.update(context, frameState, []);
+
+        // Don't load further tiles.
+        tileProvider.loadTile.andCallFake(function(context, frameState, tile) {
+            tile.state = QuadtreeTileLoadState.START;
+        });
+
+        quadtree.update(context, frameState, []);
+
+        quadtree.forEachLoadedTile(function(tile) {
+            expect(tile.state).not.toBe(QuadtreeTileLoadState.START);
+        });
+    });
 });