Implement support for mixed sampled render targets

src/gpu/gl/GrGLGpu.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLGpu.h"
 #include "GrGLStencilAttachment.h"
@@ skipping 355 matching lines @@
             // On some devices this may have a perf hit.  Also multiple render targets are disabled
             GL_CALL(Enable(GR_GL_FETCH_PER_SAMPLE_ARM));
         }
         fHWWriteToColor = kUnknown_TriState;
         // we only ever use lines in hairline mode
         GL_CALL(LineWidth(1));
     }
 
     if (resetBits & kMSAAEnable_GrGLBackendState) {
         fMSAAEnabled = kUnknown_TriState;
+
+        // In mixed samples mode coverage modulation allows the coverage to be converted to
+        // "opacity", which can then be blended into the color buffer to accomplish antialiasing.
+        // Enable coverage modulation suitable for premultiplied alpha colors.

[Chris Dalton, 2015/06/11 23:34:38]

// This state has no effect when not rendering to a mixed sampled target.

+        if (this->glCaps().shaderCaps()->mixedSamplesSupport()) {
+            GL_CALL(CoverageModulation(GR_GL_RGBA));
+        }
     }
 
     fHWActiveTextureUnitIdx = -1; // invalid
 
     if (resetBits & kTextureBinding_GrGLBackendState) {
         for (int s = 0; s < fHWBoundTextureUniqueIDs.count(); ++s) {
             fHWBoundTextureUniqueIDs[s] = SK_InvalidUniqueID;
         }
     }
 
@@ skipping 458 matching lines @@
 
 static bool renderbuffer_storage_msaa(const GrGLContext& ctx,
                                       int sampleCount,
                                       GrGLenum format,
                                       int width, int height) {
     CLEAR_ERROR_BEFORE_ALLOC(ctx.interface());
     SkASSERT(GrGLCaps::kNone_MSFBOType != ctx.caps()->msFBOType());
     switch (ctx.caps()->msFBOType()) {
         case GrGLCaps::kDesktop_ARB_MSFBOType:
         case GrGLCaps::kDesktop_EXT_MSFBOType:
+        case GrGLCaps::kMixedSamples_MSFBOType:
         case GrGLCaps::kES_3_0_MSFBOType:
             GL_ALLOC_CALL(ctx.interface(),
                             RenderbufferStorageMultisample(GR_GL_RENDERBUFFER,
                                                             sampleCount,
                                                             format,
                                                             width, height));
             break;
         case GrGLCaps::kES_Apple_MSFBOType:
             GL_ALLOC_CALL(ctx.interface(),
                             RenderbufferStorageMultisampleES2APPLE(GR_GL_RENDERBUFFER,
@@ skipping 17 matching lines @@
 }
 
 bool GrGLGpu::createRenderTargetObjects(const GrSurfaceDesc& desc,
                                         GrGpuResource::LifeCycle lifeCycle,
                                         GrGLuint texID,
                                         GrGLRenderTarget::IDDesc* idDesc) {
     idDesc->fMSColorRenderbufferID = 0;
     idDesc->fRTFBOID = 0;
     idDesc->fTexFBOID = 0;
     idDesc->fLifeCycle = lifeCycle;
+    idDesc->fSampleConfig = (GrGLCaps::kMixedSamples_MSFBOType == this->glCaps().msFBOType() &&
+                            desc.fSampleCnt > 0) ? GrRenderTarget::kStencil_SampleConfig :
+                                                   GrRenderTarget::kUnified_SampleConfig;
 
     GrGLenum status;
 
     GrGLenum msColorFormat = 0; // suppress warning
 
     if (desc.fSampleCnt > 0 && GrGLCaps::kNone_MSFBOType == this->glCaps().msFBOType()) {
         goto FAILED;
     }
 
     GL_CALL(GenFramebuffers(1, &idDesc->fTexFBOID));
@@ skipping 262 matching lines @@
 }
 }
 
 bool GrGLGpu::createStencilAttachmentForRenderTarget(GrRenderTarget* rt, int width, int height) {
     // All internally created RTs are also textures. We don't create
     // SBs for a client's standalone RT (that is a RT that isn't also a texture).
     SkASSERT(rt->asTexture());
     SkASSERT(width >= rt->width());
     SkASSERT(height >= rt->height());
 
-    int samples = rt->numSamples();
+    int samples = rt->numStencilSamples();
     GrGLStencilAttachment::IDDesc sbDesc;
 
     int stencilFmtCnt = this->glCaps().stencilFormats().count();
     for (int i = 0; i < stencilFmtCnt; ++i) {
         if (!sbDesc.fRenderbufferID) {
             GL_CALL(GenRenderbuffers(1, &sbDesc.fRenderbufferID));
         }
         if (!sbDesc.fRenderbufferID) {
             return false;
         }
@@ skipping 416 matching lines @@
     if (renderTarget->getUniqueID() != fHWBoundRenderTargetUniqueID) {
         fHWBoundRenderTargetUniqueID = SK_InvalidUniqueID;
         fStats.incRenderTargetBinds();
         GL_CALL(BindFramebuffer(GR_GL_FRAMEBUFFER, glRT->renderFBOID()));
     }
     switch (this->glCaps().invalidateFBType()) {
         case GrGLCaps::kNone_InvalidateFBType:
             SkFAIL("Should never get here.");
             break;
         case GrGLCaps::kInvalidate_InvalidateFBType:
+            if (kNVIDIA_GrGLDriver == this->glContext().driver() &&
+                this->glCaps().shaderCaps()->mixedSamplesSupport()) {

[vbuzinov, 2015/06/11 12:30:57]

The nature of glInvalidateFramebuffer bug seems to be more convoluted.  Looks
like we are getting a hang when invalidating a non-mixed-sampled FBO on
amazon.skp that is used to compute the blur effect and has a mixed-sampled FBO
as a source.  Using a broader condition here until it gets resolved.

[bsalomon, 2015/06/11 13:33:14]

Can we just disable support for framebuffer invalidation when setting up the
caps (until the issue is resolved)? That way if we were to add another code path
that uses the functionality it'd inherit the workaround.

+                // Workaround NVIDIA bug related to glInvalidateFramebuffer and mixed samples.
+                break;
+            }
             if (0 == glRT->renderFBOID()) {
                 //  When rendering to the default framebuffer the legal values for attachments
                 //  are GL_COLOR, GL_DEPTH, GL_STENCIL, ... rather than the various FBO attachment
                 //  types.
                 static const GrGLenum attachments[] = { GR_GL_COLOR };
                 GL_CALL(InvalidateFramebuffer(GR_GL_FRAMEBUFFER, SK_ARRAY_COUNT(attachments),
                         attachments));
             } else {
                 static const GrGLenum attachments[] = { GR_GL_COLOR_ATTACHMENT0 };
                 GL_CALL(InvalidateFramebuffer(GR_GL_FRAMEBUFFER, SK_ARRAY_COUNT(attachments),
@@ skipping 463 matching lines @@
                                stencilSettings,
                                GR_GL_FRONT_AND_BACK,
                                GrStencilSettings::kFront_Face);
             }
         }
         fHWStencilSettings = stencilSettings;
     }
 }
 
 void GrGLGpu::flushHWAAState(GrRenderTarget* rt, bool useHWAA) {
-    SkASSERT(!useHWAA || rt->isMultisampled());
+    SkASSERT(!useHWAA || rt->isStencilBufferMultisampled());
 
     if (this->glCaps().multisampleDisableSupport()) {
         if (useHWAA) {
             if (kYes_TriState != fMSAAEnabled) {
                 GL_CALL(Enable(GR_GL_MULTISAMPLE));
                 fMSAAEnabled = kYes_TriState;
             }
         } else {
             if (kNo_TriState != fMSAAEnabled) {
                 GL_CALL(Disable(GR_GL_MULTISAMPLE));
@@ skipping 963 matching lines @@
             this->setVertexArrayID(gpu, 0);
         }
         int attrCount = gpu->glCaps().maxVertexAttributes();
         if (fDefaultVertexArrayAttribState.count() != attrCount) {
             fDefaultVertexArrayAttribState.resize(attrCount);
         }
         attribState = &fDefaultVertexArrayAttribState;
     }
     return attribState;
 }