Merge pull request #4559 from AnalyticalGraphicsInc/shadows-polygon-o…

…ffset Fix polygon offset check for shadows
CesiumGS · Nov 1, 2016 · a7f1c6f · a7f1c6f
2 parents 957d25b + d491fa8
commit a7f1c6f
Show file tree

Hide file tree

Showing 3 changed files with 7 additions and 2 deletions.
diff --git a/CHANGES.md b/CHANGES.md
@@ -41,6 +41,7 @@ Change Log
 * Fix warning when using Webpack. [#4467](https://github.com/AnalyticalGraphicsInc/cesium/pull/4467)
 * Fix primitive bounding sphere bug that would cause a crash when loading data sources. [#4431](https://github.com/AnalyticalGraphicsInc/cesium/issues/4431)
 * Fix a crash when clustering is enabled, an entity has a label graphics defined, but the label isn't visible. [#4414](https://github.com/AnalyticalGraphicsInc/cesium/issues/4414)
+* Fixed a shadow aliasing issue where polygon offset was not being applied. [#4559](https://github.com/AnalyticalGraphicsInc/cesium/pull/4559)
 
 ### 1.26 - 2016-10-03
 

diff --git a/Source/Scene/ShadowMap.js b/Source/Scene/ShadowMap.js
@@ -185,8 +185,9 @@ define([
         this._needsUpdate = true;
 
         // In IE11 polygon offset is not functional.
+        // TODO : Also disabled for Chrome (ANGLE) temporarily. Re-enable once https://github.com/AnalyticalGraphicsInc/cesium/issues/4560 is resolved.
         var polygonOffsetSupported = true;
-        if (FeatureDetection.isInternetExplorer) {
+        if (FeatureDetection.isInternetExplorer() || (FeatureDetection.isChrome() && FeatureDetection.isWindows())) {
             polygonOffsetSupported = false;
         }
         this._polygonOffsetSupported = polygonOffsetSupported;

diff --git a/Source/Scene/ShadowMapShader.js b/Source/Scene/ShadowMapShader.js
@@ -134,6 +134,7 @@ define([
         var hasPositionVarying = defined(positionVaryingName);
 
         var usesDepthTexture = shadowMap._usesDepthTexture;
+        var polygonOffsetSupported = shadowMap._polygonOffsetSupported;
         var isPointLight = shadowMap._isPointLight;
         var isSpotLight = shadowMap._isSpotLight;
         var hasCascades = shadowMap._numberOfCascades > 1;
@@ -230,7 +231,9 @@ define([
         if (isTerrain) {
             // Scale depth bias based on view distance to reduce z-fighting in distant terrain
             fsSource += '    shadowParameters.depthBias *= max(depth * 0.01, 1.0); \n';
-        } else {
+        } else if (!polygonOffsetSupported) {
+            // If polygon offset isn't supported push the depth back based on view, however this
+            // causes light leaking at further away views
             fsSource += '    shadowParameters.depthBias *= mix(1.0, 100.0, depth * 0.0015); \n';
         }