Implement support for mixed sampled render targets

src/gpu/gl/GrGLGpu.cpp

Index: src/gpu/gl/GrGLGpu.cpp
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index 7090ca93d415ed5de8816b3dbf32268f0ed408ba..f41794ff22c62adc9df9ba594e398d3727733d8c 100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -311,6 +311,7 @@ void GrGLGpu::onResetContext(uint32_t resetBits) {
 
     if (resetBits & kMSAAEnable_GrGLBackendState) {
         fMSAAEnabled = kUnknown_TriState;
+        fCoverageModulationEnabled = kUnknown_TriState;
     }
 
     fHWActiveTextureUnitIdx = -1; // invalid
@@ -447,6 +448,7 @@ GrRenderTarget* GrGLGpu::onWrapBackendRenderTarget(const GrBackendRenderTargetDe
     GrGLuint fboID = static_cast<GrGLuint>(wrapDesc.fRenderTargetHandle);
     idDesc.fRenderFBO.reset(SkNEW_ARGS(GrGLFBO, (fboID)));
     idDesc.fMSColorRenderbufferID = 0;
+    idDesc.fSampleConfig = wrapDesc.fSampleConfig;
     idDesc.fLifeCycle = GrGpuResource::kWrapped_LifeCycle;
 
     GrSurfaceDesc desc;
@@ -794,6 +796,7 @@ static bool renderbuffer_storage_msaa(GrGLContext& ctx,
     switch (ctx.caps()->msFBOType()) {
         case GrGLCaps::kDesktop_ARB_MSFBOType:
         case GrGLCaps::kDesktop_EXT_MSFBOType:
+        case GrGLCaps::kStencil_MSFBOType:
         case GrGLCaps::kES_3_0_MSFBOType:
             GL_ALLOC_CALL(ctx.interface(),
                             RenderbufferStorageMultisample(GR_GL_RENDERBUFFER,
@@ -828,6 +831,9 @@ bool GrGLGpu::createRenderTargetObjects(const GrSurfaceDesc& desc, bool budgeted
     idDesc->fMSColorRenderbufferID = 0;
     idDesc->fLifeCycle = budgeted ? GrGpuResource::kCached_LifeCycle :
                                     GrGpuResource::kUncached_LifeCycle;
+    idDesc->fSampleConfig = GrGLCaps::kStencil_MSFBOType ==
+                            this->glCaps().msFBOType() ? kStencil_GrSampleConfig :
+                                                         kUnified_GrSampleConfig;
 
     GrGLenum status;
 
@@ -1147,7 +1153,7 @@ bool GrGLGpu::createStencilBufferForRenderTarget(GrRenderTarget* rt, int width,
     SkASSERT(width >= rt->width());
     SkASSERT(height >= rt->height());
 
-    int samples = rt->numSamples();
+    int samples = rt->numSamples(kStencil_GrSampleConfig);
     GrGLStencilBuffer::IDDesc sbDesc;
 
     int stencilFmtCnt = this->glCaps().stencilFormats().count();
@@ -2095,9 +2101,10 @@ void GrGLGpu::flushStencil(const GrStencilSettings& stencilSettings) {
 }
 
 void GrGLGpu::flushHWAAState(GrRenderTarget* rt, bool useHWAA) {
-    SkASSERT(!useHWAA || rt->isMultisampled());
+    SkASSERT(!useHWAA || rt->isMultisampled(kStencil_GrSampleConfig));
 
-    if (kGL_GrGLStandard == this->glStandard()) {
+    if (kGL_GrGLStandard == this->glStandard() ||
+        this->glCaps().fbMixedSamplesSupport()) {
         if (useHWAA) {
             if (kYes_TriState != fMSAAEnabled) {
                 GL_CALL(Enable(GR_GL_MULTISAMPLE));
@@ -2110,6 +2117,19 @@ void GrGLGpu::flushHWAAState(GrRenderTarget* rt, bool useHWAA) {
             }
         }
     }
+    if (this->glCaps().fbMixedSamplesSupport()) {
+        if (useHWAA && kStencil_GrSampleConfig == rt->sampleConfig()) {
+            if (kYes_TriState != fCoverageModulationEnabled) {
+                GL_CALL(CoverageModulation(GR_GL_RGBA));

[Chris Dalton, 2015/03/17 00:39:35]

I verified with Brian that Skia always writes premultiplied alpha. So this is
correct to always just do GL_RGBA.

+                fCoverageModulationEnabled = kYes_TriState;
+            }
+        } else {
+            if (kNo_TriState != fCoverageModulationEnabled) {
+                GL_CALL(CoverageModulation(GR_GL_NONE));
+                fCoverageModulationEnabled = kNo_TriState;
+            }
+        }
+    }
 }
 
 void GrGLGpu::flushBlend(const GrXferProcessor::BlendInfo& blendInfo) {