Fix double blend in GrAAConvexPathRenderer

src/gpu/GrAAConvexPathRenderer.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrAAConvexPathRenderer.h"
 
@@ skipping 407 matching lines @@
             verts[*v + 2].fUV.set(0, 0);
             verts[*v + 3].fUV.set(0, -SK_Scalar1);
             verts[*v + 4].fUV.set(0, -SK_Scalar1);
 
             verts[*v + 0].fD0 = verts[*v + 0].fD1 = -SK_Scalar1;
             verts[*v + 1].fD0 = verts[*v + 1].fD1 = -SK_Scalar1;
             verts[*v + 2].fD0 = verts[*v + 2].fD1 = -SK_Scalar1;
             verts[*v + 3].fD0 = verts[*v + 3].fD1 = -SK_Scalar1;
             verts[*v + 4].fD0 = verts[*v + 4].fD1 = -SK_Scalar1;
 
-            idxs[*i + 0] = *v + 0;
-            idxs[*i + 1] = *v + 2;
-            idxs[*i + 2] = *v + 1;
+            idxs[*i + 0] = *v + 3;
+            idxs[*i + 1] = *v + 1;
+            idxs[*i + 2] = *v + 2;
 
-            idxs[*i + 3] = *v + 3;
-            idxs[*i + 4] = *v + 1;
+            idxs[*i + 3] = *v + 4;
+            idxs[*i + 4] = *v + 3;
             idxs[*i + 5] = *v + 2;
 
-            idxs[*i + 6] = *v + 4;
-            idxs[*i + 7] = *v + 3;
-            idxs[*i + 8] = *v + 2;
+            *i += 6;
+
+            // Draw the interior fan if it exists.
+            // TODO: Detect and combine colinear segments. This will ensure we catch every case
+            // with no interior, and that the resulting shared edge uses the same endpoints.
+            if (count >= 3) {
+                idxs[*i + 0] = *v + 0;
+                idxs[*i + 1] = *v + 2;
+                idxs[*i + 2] = *v + 1;
+
+                *i += 3;
+            }
 
             *v += 5;
-            *i += 9;
         } else {
             SkPoint qpts[] = {sega.endPt(), segb.fPts[0], segb.fPts[1]};
 
             SkVector midVec = segb.fNorms[0] + segb.fNorms[1];
             midVec.normalize();
 
             verts[*v + 0].fPos = fanPt;
             verts[*v + 1].fPos = qpts[0];
             verts[*v + 2].fPos = qpts[2];
             verts[*v + 3].fPos = qpts[0] + segb.fNorms[0];
@@ skipping 23 matching lines @@
             idxs[*i + 1] = *v + 1;
             idxs[*i + 2] = *v + 2;
             idxs[*i + 3] = *v + 4;
             idxs[*i + 4] = *v + 3;
             idxs[*i + 5] = *v + 2;
 
             idxs[*i + 6] = *v + 5;
             idxs[*i + 7] = *v + 3;
             idxs[*i + 8] = *v + 4;
 
-            idxs[*i +  9] = *v + 0;
-            idxs[*i + 10] = *v + 2;
-            idxs[*i + 11] = *v + 1;
+            *i += 9;
+
+            // Draw the interior fan if it exists.
+            // TODO: Detect and combine colinear segments. This will ensure we catch every case
+            // with no interior, and that the resulting shared edge uses the same endpoints.
+            if (count >= 3) {

[Chris Dalton, 2015/04/29 16:38:04]

I decided to err on the side of minimal code change, but let me know if you want
me to rearrange things so we only write fanPt to the vertex array when we take
this branch.

+                idxs[*i + 0] = *v + 0;
+                idxs[*i + 1] = *v + 2;
+                idxs[*i + 2] = *v + 1;
+
+                *i += 3;
+            }
 
             *v += 6;
-            *i += 12;
         }
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /*
  * Quadratic specified by 0=u^2-v canonical coords. u and v are the first
  * two components of the vertex attribute. Coverage is based on signed
  * distance with negative being inside, positive outside. The edge is specified in
@@ skipping 384 matching lines @@
     geometry.fColor = color;
     geometry.fViewMatrix = vm;
     geometry.fPath = path;
 
     SkAutoTUnref<GrBatch> batch(AAConvexPathBatch::Create(geometry));
     target->drawBatch(pipelineBuilder, batch, &devRect);
 
     return true;
 
 }