Fix for Ovals/RRects on N4 missing interior rectangles.

src/gpu/GrOvalRenderer.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrOvalRenderer.h"
 
 #include "GrEffect.h"
@@ skipping 203 matching lines @@
 
             builder->addVarying(kVec4f_GrSLType, "EllipseRadii", &vsRadiiName, &fsRadiiName);
             const SkString* attr1Name =
                 builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[1]);
             builder->vsCodeAppendf("\t%s = %s;\n", vsRadiiName, attr1Name->c_str());
 
             // for outer curve
             builder->fsCodeAppendf("\tvec2 scaledOffset = %s*%s.xy;\n", fsOffsetName, fsRadiiName);
             builder->fsCodeAppend("\tfloat test = dot(scaledOffset, scaledOffset) - 1.0;\n");
             builder->fsCodeAppendf("\tvec2 grad = 2.0*scaledOffset*%s.xy;\n", fsRadiiName);
-            builder->fsCodeAppend("\tfloat invlen = inversesqrt(dot(grad, grad));\n");
+            builder->fsCodeAppend("\tfloat grad_dot = dot(grad, grad);\n");

[robertphillips, 2013/07/01 18:35:41]

comment here as to why we're doing this?

+            builder->fsCodeAppend("\tgrad_dot = max(grad_dot, 1.0e-4);\n");

[bsalomon, 2013/07/01 18:36:03]

Could use a comment here about why this number was selected.

+            builder->fsCodeAppend("\tfloat invlen = inversesqrt(grad_dot);\n");
             builder->fsCodeAppend("\tfloat edgeAlpha = clamp(0.5-test*invlen, 0.0, 1.0);\n");
 
             // for inner curve
             if (ellipseEffect.isStroked()) {
                 builder->fsCodeAppendf("\tscaledOffset = %s*%s.zw;\n", fsOffsetName, fsRadiiName);
                 builder->fsCodeAppend("\ttest = dot(scaledOffset, scaledOffset) - 1.0;\n");
                 builder->fsCodeAppendf("\tgrad = 2.0*scaledOffset*%s.zw;\n", fsRadiiName);
                 builder->fsCodeAppend("\tinvlen = inversesqrt(dot(grad, grad));\n");
                 builder->fsCodeAppend("\tedgeAlpha *= clamp(0.5+test*invlen, 0.0, 1.0);\n");
             }
@@ skipping 566 matching lines @@
         // Expand the rect so all the pixels will be captured.
         bounds.outset(SK_ScalarHalf, SK_ScalarHalf);
 
         SkScalar yCoords[4] = {
             bounds.fTop,
             bounds.fTop + yOuterRadius,
             bounds.fBottom - yOuterRadius,
             bounds.fBottom
         };
         SkScalar yOuterOffsets[4] = {
-            -yOuterRadius,
+            yOuterRadius,
             SK_ScalarNearlyZero, // we're using inversesqrt() in the shader, so can't be exactly 0
             SK_ScalarNearlyZero,
             yOuterRadius
         };
 
         for (int i = 0; i < 4; ++i) {
             verts->fPos = SkPoint::Make(bounds.fLeft, yCoords[i]);
-            verts->fOffset = SkPoint::Make(-xOuterRadius, yOuterOffsets[i]);
+            verts->fOffset = SkPoint::Make(xOuterRadius, yOuterOffsets[i]);
             verts->fOuterRadii = SkPoint::Make(xRadRecip, yRadRecip);
             verts->fInnerRadii = SkPoint::Make(xInnerRadRecip, yInnerRadRecip);
             verts++;
 
             verts->fPos = SkPoint::Make(bounds.fLeft + xOuterRadius, yCoords[i]);
             verts->fOffset = SkPoint::Make(SK_ScalarNearlyZero, yOuterOffsets[i]);
             verts->fOuterRadii = SkPoint::Make(xRadRecip, yRadRecip);
             verts->fInnerRadii = SkPoint::Make(xInnerRadRecip, yInnerRadRecip);
             verts++;
 
@@ skipping 11 matching lines @@
         }
 
         // drop out the middle quad if we're stroked
         int indexCnt = isStroked ? GR_ARRAY_COUNT(gRRectIndices)-6 : GR_ARRAY_COUNT(gRRectIndices);
         target->setIndexSourceToBuffer(indexBuffer);
         target->drawIndexed(kTriangles_GrPrimitiveType, 0, 0, 16, indexCnt, &bounds);
     }
 
     return true;
 }