| /* |
| * 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 "gl/builders/GrGLProgramBuilder.h" |
| #include "GrDitherEffect.h" |
| |
| #include "gl/GrGLProcessor.h" |
| #include "gl/GrGLSL.h" |
| #include "GrTBackendProcessorFactory.h" |
| |
| #include "SkRect.h" |
| |
| ////////////////////////////////////////////////////////////////////////////// |
| |
| class GLDitherEffect; |
| |
| class DitherEffect : public GrFragmentProcessor { |
| public: |
| static GrFragmentProcessor* Create() { |
| GR_CREATE_STATIC_FRAGMENT_PROCESSOR(gDitherEffect, DitherEffect, ()) |
| return SkRef(gDitherEffect); |
| } |
| |
| virtual ~DitherEffect() {}; |
| static const char* Name() { return "Dither"; } |
| |
| typedef GLDitherEffect GLProcessor; |
| |
| virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE; |
| |
| virtual const GrBackendFragmentProcessorFactory& getFactory() const SK_OVERRIDE { |
| return GrTBackendFragmentProcessorFactory<DitherEffect>::getInstance(); |
| } |
| |
| private: |
| DitherEffect() { |
| this->setWillReadFragmentPosition(); |
| } |
| |
| // All dither effects are equal |
| virtual bool onIsEqual(const GrProcessor&) const SK_OVERRIDE { return true; } |
| |
| GR_DECLARE_FRAGMENT_PROCESSOR_TEST; |
| |
| typedef GrFragmentProcessor INHERITED; |
| }; |
| |
| void DitherEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const { |
| *validFlags = 0; |
| } |
| |
| ////////////////////////////////////////////////////////////////////////////// |
| |
| GR_DEFINE_FRAGMENT_PROCESSOR_TEST(DitherEffect); |
| |
| GrFragmentProcessor* DitherEffect::TestCreate(SkRandom*, |
| GrContext*, |
| const GrDrawTargetCaps&, |
| GrTexture*[]) { |
| return DitherEffect::Create(); |
| } |
| |
| ////////////////////////////////////////////////////////////////////////////// |
| |
| class GLDitherEffect : public GrGLFragmentProcessor { |
| public: |
| GLDitherEffect(const GrBackendProcessorFactory&, const GrProcessor&); |
| |
| virtual void emitCode(GrGLProgramBuilder* builder, |
| const GrFragmentProcessor& fp, |
| const GrProcessorKey& key, |
| const char* outputColor, |
| const char* inputColor, |
| const TransformedCoordsArray&, |
| const TextureSamplerArray&) SK_OVERRIDE; |
| |
| private: |
| typedef GrGLFragmentProcessor INHERITED; |
| }; |
| |
| GLDitherEffect::GLDitherEffect(const GrBackendProcessorFactory& factory, |
| const GrProcessor&) |
| : INHERITED (factory) { |
| } |
| |
| void GLDitherEffect::emitCode(GrGLProgramBuilder* builder, |
| const GrFragmentProcessor& fp, |
| const GrProcessorKey& key, |
| const char* outputColor, |
| const char* inputColor, |
| const TransformedCoordsArray&, |
| const TextureSamplerArray& samplers) { |
| GrGLFragmentShaderBuilder* fsBuilder = builder->getFragmentShaderBuilder(); |
| // Generate a random number based on the fragment position. For this |
| // random number generator, we use the "GLSL rand" function |
| // that seems to be floating around on the internet. It works under |
| // the assumption that sin(<big number>) oscillates with high frequency |
| // and sampling it will generate "randomness". Since we're using this |
| // for rendering and not cryptography it should be OK. |
| |
| // For each channel c, add the random offset to the pixel to either bump |
| // it up or let it remain constant during quantization. |
| fsBuilder->codeAppendf("\t\tfloat r = " |
| "fract(sin(dot(%s.xy ,vec2(12.9898,78.233))) * 43758.5453);\n", |
| fsBuilder->fragmentPosition()); |
| fsBuilder->codeAppendf("\t\t%s = (1.0/255.0) * vec4(r, r, r, r) + %s;\n", |
| outputColor, GrGLSLExpr4(inputColor).c_str()); |
| } |
| |
| ////////////////////////////////////////////////////////////////////////////// |
| |
| GrFragmentProcessor* GrDitherEffect::Create() { return DitherEffect::Create(); } |