Implement support for mixed sampled render targets

src/gpu/effects/GrPorterDuffXferProcessor.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 "effects/GrPorterDuffXferProcessor.h"
 
 #include "GrBlend.h"
@@ skipping 384 matching lines @@
         } else {
             fDstBlend = kOne_GrBlendCoeff;
             return GrXferProcessor::kSkipDraw_OptFlag;
         }
     }
 
     // if we don't have coverage we can check whether the dst
     // has to read at all. If not, we'll disable blending.
     if (!hasCoverage) {
         if (dstCoeffIsZero) {
-            if (kOne_GrBlendCoeff == fSrcBlend) {
+            if (kOne_GrBlendCoeff == fSrcBlend &&
+                !colorPOI.needsCoverageModulation()) {

[bsalomon, 2015/03/31 16:37:33]

I know needCoverageModulation mirrors the extension language but in this context
I find it confusing. We use "coverage" to mean any fractional pixel coverage no
matter how it is implemented (stencil, fragment shader calculation) and we
always use it to "modulate" somewhere in the pipeline (glBlend or in the frag
shader).

Could we use something a little more descriptive?

applyStencilCoverageModulation? modulateByStencilCoverageFraction?

[vbuzinov, 2015/04/02 13:10:37]

Done.

                 // if there is no coverage and coeffs are (1,0) then we
                 // won't need to read the dst at all, it gets replaced by src
                 fDstBlend = kZero_GrBlendCoeff;
                 return GrXferProcessor::kNone_Opt;
             } else if (kZero_GrBlendCoeff == fSrcBlend) {
                 // if the op is "clear" then we don't need to emit a color
                 // or blend, just write transparent black into the dst.
                 fSrcBlend = kOne_GrBlendCoeff;
                 fDstBlend = kZero_GrBlendCoeff;
                 return GrXferProcessor::kIgnoreColor_OptFlag |
@@ skipping 284 matching lines @@
 GR_DEFINE_XP_FACTORY_TEST(GrPorterDuffXPFactory);
 
 GrXPFactory* GrPorterDuffXPFactory::TestCreate(SkRandom* random,
                                                GrContext*,
                                                const GrDrawTargetCaps&,
                                                GrTexture*[]) {
     SkXfermode::Mode mode = SkXfermode::Mode(random->nextULessThan(SkXfermode::kLastCoeffMode));
     return GrPorterDuffXPFactory::Create(mode);
 }