Add perspective divide when we're mapping down to a 2D varying

src/gpu/GrGeometryProcessor.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGeometryProcessor.h"
 
 #include "GrCoordTransform.h"
@@ skipping 200 matching lines @@
             SkNEW_APPEND_TO_TARRAY(&(*tout)[i], GrGLProcessor::TransformedCoords,
                                    (SkString(v.fsIn()), varyingType));
 
             // varying = matrix * coords (logically)
             if (kDevice_GrCoordSet == coordType) {
                 if (kVec2f_GrSLType == varyingType) {
                     if (kVec2f_GrSLType == posVar.getType()) {
                         vb->codeAppendf("%s = (%s * vec3(%s, 1)).xy;",
                                         v.vsOut(), uniName, posVar.c_str());
                     } else {
-                        vb->codeAppendf("%s = (%s * %s).xy;", v.vsOut(), uniName, posVar.c_str());
+                        // The brackets here are just to scope the temp variable
+                        vb->codeAppendf("{ vec3 temp = %s * %s;", uniName, posVar.c_str());
+                        vb->codeAppendf("%s = vec2(temp.x/temp.z, temp.y/temp.z); }", v.vsOut());
                     }
                 } else {
                     if (kVec2f_GrSLType == posVar.getType()) {
                         vb->codeAppendf("%s = %s * vec3(%s, 1);",
                                         v.vsOut(), uniName, posVar.c_str());
                     } else {
                         vb->codeAppendf("%s = %s * %s;", v.vsOut(), uniName, posVar.c_str());
                     }
                 }
             } else {
@@ skipping 328 matching lines @@
                                                           const GrGLCaps& caps) const {
     SkASSERT(caps.nvprSupport() != GrGLCaps::kNone_NvprSupport);
     if (caps.nvprSupport() == GrGLCaps::kLegacy_NvprSupport) {
         return SkNEW_ARGS(GrGLLegacyPathProcessor, (*this, bt,
                                                     caps.maxFixedFunctionTextureCoords()));
     } else {
         return SkNEW_ARGS(GrGLNormalPathProcessor, (*this, bt));
     }
 }