Merge pull request #6788 from AnalyticalGraphicsInc/fix-polygon-tangents

Fix tangent/bitangent when stRotation is applied
CesiumGS · Jul 11, 2018 · 2fa8660 · 2fa8660
2 parents b32bc17 + 18aefea
commit 2fa8660
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Showing 3 changed files with 31 additions and 7 deletions.
diff --git a/CHANGES.md b/CHANGES.md
@@ -16,6 +16,7 @@ Change Log
 * Fixed `PolygonGeometry` when using `VertexFormat.POSITION_ONLY`, `perPositionHeight` and `extrudedHeight` [#6790](expect(https://github.com/AnalyticalGraphicsInc/cesium/pull/6790)
 * Fixed a bug that was preventing 3D Tilesets on the opposite side of the globe from being occluded [#6714](https://github.com/AnalyticalGraphicsInc/cesium/issues/6714)
 * Fixed a bug where 3D Tilesets using the `region` bounding volume don't get transformed when the tileset's `modelMatrix` changes. [6755](https://github.com/AnalyticalGraphicsInc/cesium/pull/6755)
+* Fixed `PolygonGeometry` and `EllipseGeometry` tangent and bitangent attributes when a texture rotation is used [#6788](https://github.com/AnalyticalGraphicsInc/cesium/pull/6788)
 
 ### 1.47 - 2018-07-02
 

diff --git a/Source/Core/EllipseGeometry.js b/Source/Core/EllipseGeometry.js
@@ -62,6 +62,7 @@ define([
     var scratchCartesian4 = new Cartesian3();
     var texCoordScratch = new Cartesian2();
     var textureMatrixScratch = new Matrix3();
+    var tangentMatrixScratch = new Matrix3();
     var quaternionScratch = new Quaternion();
 
     var scratchNormal = new Cartesian3();
@@ -104,8 +105,19 @@ define([
 
         var geodeticNormal = ellipsoid.scaleToGeodeticSurface(center, scratchCartesian1);
         ellipsoid.geodeticSurfaceNormal(geodeticNormal, geodeticNormal);
-        var rotation = Quaternion.fromAxisAngle(geodeticNormal, stRotation, quaternionScratch);
-        var textureMatrix = Matrix3.fromQuaternion(rotation, textureMatrixScratch);
+
+        var textureMatrix = textureMatrixScratch;
+        var tangentMatrix = tangentMatrixScratch;
+        if (stRotation !== 0) {
+            var rotation = Quaternion.fromAxisAngle(geodeticNormal, stRotation, quaternionScratch);
+            textureMatrix = Matrix3.fromQuaternion(rotation, textureMatrix);
+
+            rotation = Quaternion.fromAxisAngle(geodeticNormal, -stRotation, quaternionScratch);
+            tangentMatrix = Matrix3.fromQuaternion(rotation, tangentMatrix);
+        } else {
+            textureMatrix = Matrix3.clone(Matrix3.IDENTITY, textureMatrix);
+            tangentMatrix = Matrix3.clone(Matrix3.IDENTITY, tangentMatrix);
+        }
 
         var minTexCoord = Cartesian2.fromElements(Number.POSITIVE_INFINITY, Number.POSITIVE_INFINITY, scratchMinTexCoord);
         var maxTexCoord = Cartesian2.fromElements(Number.NEGATIVE_INFINITY, Number.NEGATIVE_INFINITY, scratchMaxTexCoord);
@@ -152,7 +164,7 @@ define([
                 if (vertexFormat.normal || vertexFormat.tangent || vertexFormat.bitangent) {
                     if (vertexFormat.tangent || vertexFormat.bitangent) {
                         tangent = Cartesian3.normalize(Cartesian3.cross(Cartesian3.UNIT_Z, normal, tangent), tangent);
-                        Matrix3.multiplyByVector(textureMatrix, tangent, tangent);
+                        Matrix3.multiplyByVector(tangentMatrix, tangent, tangent);
                     }
                     if (vertexFormat.normal) {
                         normals[i] = normal.x;

diff --git a/Source/Core/PolygonGeometry.js b/Source/Core/PolygonGeometry.js
@@ -90,6 +90,7 @@ define([
     var appendTextureCoordinatesCartesian3 = new Cartesian3();
     var appendTextureCoordinatesQuaternion = new Quaternion();
     var appendTextureCoordinatesMatrix3 = new Matrix3();
+    var tangentMatrixScratch = new Matrix3();
 
     function computeAttributes(options) {
         var vertexFormat = options.vertexFormat;
@@ -134,8 +135,18 @@ define([
             var bitangent = scratchBitangent;
             var recomputeNormal = true;
 
-            var rotation = Quaternion.fromAxisAngle(tangentPlane._plane.normal, stRotation, appendTextureCoordinatesQuaternion);
-            var textureMatrix = Matrix3.fromQuaternion(rotation, appendTextureCoordinatesMatrix3);
+            var textureMatrix = appendTextureCoordinatesMatrix3;
+            var tangentRotationMatrix = tangentMatrixScratch;
+            if (stRotation !== 0.0) {
+                var rotation = Quaternion.fromAxisAngle(tangentPlane._plane.normal, stRotation, appendTextureCoordinatesQuaternion);
+                textureMatrix = Matrix3.fromQuaternion(rotation, textureMatrix);
+
+                rotation = Quaternion.fromAxisAngle(tangentPlane._plane.normal, -stRotation, appendTextureCoordinatesQuaternion);
+                tangentRotationMatrix = Matrix3.fromQuaternion(rotation, tangentRotationMatrix);
+            } else {
+                textureMatrix = Matrix3.clone(Matrix3.IDENTITY, textureMatrix);
+                tangentRotationMatrix = Matrix3.clone(Matrix3.IDENTITY, tangentRotationMatrix);
+            }
 
             var bottomOffset = 0;
             var bottomOffset2 = 0;
@@ -206,14 +217,14 @@ define([
                             if (perPositionHeight) {
                                 scratchPerPosNormal = Cartesian3.fromArray(normals, attrIndex, scratchPerPosNormal);
                                 scratchPerPosTangent = Cartesian3.cross(Cartesian3.UNIT_Z, scratchPerPosNormal, scratchPerPosTangent);
-                                scratchPerPosTangent = Cartesian3.normalize(Matrix3.multiplyByVector(textureMatrix, scratchPerPosTangent, scratchPerPosTangent), scratchPerPosTangent);
+                                scratchPerPosTangent = Cartesian3.normalize(Matrix3.multiplyByVector(tangentRotationMatrix, scratchPerPosTangent, scratchPerPosTangent), scratchPerPosTangent);
                                 if (vertexFormat.bitangent) {
                                     scratchPerPosBitangent = Cartesian3.normalize(Cartesian3.cross(scratchPerPosNormal, scratchPerPosTangent, scratchPerPosBitangent), scratchPerPosBitangent);
                                 }
                             }
 
                             tangent = Cartesian3.cross(Cartesian3.UNIT_Z, normal, tangent);
-                            tangent = Cartesian3.normalize(Matrix3.multiplyByVector(textureMatrix, tangent, tangent), tangent);
+                            tangent = Cartesian3.normalize(Matrix3.multiplyByVector(tangentRotationMatrix, tangent, tangent), tangent);
                             if (vertexFormat.bitangent) {
                                 bitangent = Cartesian3.normalize(Cartesian3.cross(normal, tangent, bitangent), bitangent);
                             }