Fixed traversal bug when skipLevelOfDetail is false

Author: lilleyse

CHANGES.md

@@ -19,6 +19,7 @@ Change Log
 * Fixed a 3D Tiles point cloud bug causing a stray point to appear at the center of the screen on certain hardware. [#5599](https://github.com/AnalyticalGraphicsInc/cesium/issues/5599)
 * Fixed removing multiple event listeners within event callbacks. [#5827](https://github.com/AnalyticalGraphicsInc/cesium/issues/5827)
 * Running `buildApps` now creates a built version of Sandcastle which uses the built version of Cesium for better performance.
+* Fixed a tileset traversal bug when the `skipLevelOfDetail` optimization is off.
 
 ### 1.37 - 2017-09-01
 

Source/Scene/Cesium3DTilesetTraversal.js

@@ -509,7 +509,7 @@ define([
         if (!tile.hasTilesetContent) {
             if (tile.refine === Cesium3DTileRefine.ADD) {
                 // Always load additive tiles
-                loadTile(tileset, tile, this.frameState);
+                loadTile(tileset, tile, this.frameState, true);
                 if (hasAdditiveContent(tile)) {
                     tileset._desiredTiles.push(tile);
                 }
@@ -635,9 +635,16 @@ define([
         }
     }
 
+    function checkAdditiveVisibility(tileset, tile, frameState) {
+        if (defined(tile.parent) && (tile.parent.refine === Cesium3DTileRefine.ADD)) {
+            return isVisibleAndMeetsSSE(tileset, tile, frameState);
+        }
+        return true;
+    }
+
     function loadTile(tileset, tile, frameState, checkVisibility) {
         if ((tile.contentUnloaded || tile.contentExpired) && tile._requestedFrame !== frameState.frameNumber) {
-            if (!checkVisibility || isVisibleAndMeetsSSE(tileset, tile, frameState)) {
+            if (!checkVisibility || checkAdditiveVisibility(tileset, tile, frameState)) {
                 tile._requestedFrame = frameState.frameNumber;
                 tileset._requestedTiles.push(tile);
             }