| /* |
| * 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 "src/gpu/ganesh/effects/GrDisableColorXP.h" |
| |
| #include "src/gpu/Blend.h" |
| #include "src/gpu/ganesh/GrShaderCaps.h" |
| #include "src/gpu/ganesh/GrXferProcessor.h" |
| #include "src/gpu/ganesh/glsl/GrGLSLFragmentShaderBuilder.h" |
| |
| #include <memory> |
| |
| namespace skgpu { |
| class KeyBuilder; |
| class Swizzle; |
| } |
| |
| /** |
| * This xfer processor disables color writing. Thus color and coverage and ignored and no blending |
| * occurs. This XP is usful for things like stenciling. |
| */ |
| class DisableColorXP : public GrXferProcessor { |
| public: |
| DisableColorXP() : INHERITED(kDisableColorXP_ClassID) {} |
| |
| private: |
| const char* name() const override { return "Disable Color"; } |
| bool onIsEqual(const GrXferProcessor& xpBase) const override { return true; } |
| void onAddToKey(const GrShaderCaps&, skgpu::KeyBuilder*) const override {} |
| void onGetBlendInfo(skgpu::BlendInfo* blendInfo) const override { |
| blendInfo->fWritesColor = false; |
| } |
| std::unique_ptr<ProgramImpl> makeProgramImpl() const override; |
| |
| using INHERITED = GrXferProcessor; |
| }; |
| |
| std::unique_ptr<GrXferProcessor::ProgramImpl> DisableColorXP::makeProgramImpl() const { |
| class Impl : public ProgramImpl { |
| private: |
| void emitOutputsForBlendState(const EmitArgs& args) override { |
| if (args.fShaderCaps->fMustWriteToFragColor) { |
| // This emit code should be empty. However, on the nexus 6 there is a driver bug |
| // where if you do not give gl_FragColor a value, the gl context is lost and we end |
| // up drawing nothing. So this fix just sets the gl_FragColor arbitrarily to 0. |
| // https://bugs.chromium.org/p/chromium/issues/detail?id=445377 |
| GrGLSLXPFragmentBuilder* fragBuilder = args.fXPFragBuilder; |
| fragBuilder->codeAppendf("%s = half4(0);", args.fOutputPrimary); |
| } |
| } |
| |
| void emitWriteSwizzle(GrGLSLXPFragmentBuilder*, |
| const skgpu::Swizzle&, |
| const char*, |
| const char*) const override { |
| // Don't write any swizzling. This makes sure the final shader does not output a color. |
| } |
| }; |
| |
| return std::make_unique<Impl>(); |
| } |
| |
| sk_sp<const GrXferProcessor> GrDisableColorXPFactory::MakeXferProcessor() { |
| return sk_make_sp<DisableColorXP>(); |
| } |
| |
| GR_DEFINE_XP_FACTORY_TEST(GrDisableColorXPFactory) |
| |
| #if defined(GR_TEST_UTILS) |
| const GrXPFactory* GrDisableColorXPFactory::TestGet(GrProcessorTestData*) { |
| return GrDisableColorXPFactory::Get(); |
| } |
| #endif |