| /* |
| * Copyright 2017 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef GrCCPRCubicProcessor_DEFINED |
| #define GrCCPRCubicProcessor_DEFINED |
| |
| #include "ccpr/GrCCPRCoverageProcessor.h" |
| |
| class GrGLSLGeometryBuilder; |
| |
| /** |
| * This class renders the coverage of convex closed cubic segments using the techniques outlined in |
| * "Resolution Independent Curve Rendering using Programmable Graphics Hardware" by Charles Loop and |
| * Jim Blinn: |
| * |
| * https://www.microsoft.com/en-us/research/wp-content/uploads/2005/01/p1000-loop.pdf |
| * |
| * The caller is expected to chop cubics at the KLM roots (a.k.a. inflection points and loop |
| * intersection points, resulting in necessarily convex segments) before feeding them into this |
| * processor. |
| * |
| * The curves are rendered in two passes: |
| * |
| * Pass 1: Draw the (convex) bezier quadrilateral, inset by 1/2 pixel all around, and use the |
| * gradient-based AA technique outlined in the Loop/Blinn paper to compute coverage. |
| * |
| * Pass 2: Draw a border around the previous inset, up to the bezier quadrilatral's conservative |
| * raster hull, and compute coverage using pseudo MSAA. This pass is necessary because the |
| * gradient approach does not work near the L and M lines. |
| * |
| * FIXME: The pseudo MSAA border is slow and ugly. We should investigate an alternate solution of |
| * just approximating the curve with straight lines for short distances across the problem points |
| * instead. |
| */ |
| class GrCCPRCubicProcessor : public GrCCPRCoverageProcessor::PrimitiveProcessor { |
| public: |
| enum class Type { |
| kSerpentine, |
| kLoop |
| }; |
| |
| GrCCPRCubicProcessor(Type type) |
| : INHERITED(CoverageType::kShader) |
| , fType(type) |
| , fInset(kVec3f_GrSLType) |
| , fTS(kFloat_GrSLType) |
| , fKLMMatrix("klm_matrix", kMat33f_GrSLType, GrShaderVar::kNonArray, |
| kHigh_GrSLPrecision) |
| , fKLMDerivatives("klm_derivatives", kVec2f_GrSLType, 3, kHigh_GrSLPrecision) {} |
| |
| void resetVaryings(GrGLSLVaryingHandler* varyingHandler) override { |
| varyingHandler->addVarying("insets", &fInset, kHigh_GrSLPrecision); |
| varyingHandler->addVarying("ts", &fTS, kHigh_GrSLPrecision); |
| } |
| |
| void onEmitVertexShader(const GrCCPRCoverageProcessor&, GrGLSLVertexBuilder*, |
| const TexelBufferHandle& pointsBuffer, const char* atlasOffset, |
| const char* rtAdjust, GrGPArgs*) const override; |
| void emitWind(GrGLSLGeometryBuilder*, const char* rtAdjust, const char* outputWind) const final; |
| void onEmitGeometryShader(GrGLSLGeometryBuilder*, const char* emitVertexFn, const char* wind, |
| const char* rtAdjust) const final; |
| |
| protected: |
| virtual void emitCubicGeometry(GrGLSLGeometryBuilder*, const char* emitVertexFn, |
| const char* wind, const char* rtAdjust) const = 0; |
| |
| const Type fType; |
| GrGLSLVertToGeo fInset; |
| GrGLSLVertToGeo fTS; |
| GrShaderVar fKLMMatrix; |
| GrShaderVar fKLMDerivatives; |
| |
| typedef GrCCPRCoverageProcessor::PrimitiveProcessor INHERITED; |
| }; |
| |
| class GrCCPRCubicInsetProcessor : public GrCCPRCubicProcessor { |
| public: |
| GrCCPRCubicInsetProcessor(Type type) |
| : INHERITED(type) |
| , fKLM(kVec3f_GrSLType) |
| , fGradMatrix(kMat22f_GrSLType) {} |
| |
| void resetVaryings(GrGLSLVaryingHandler* varyingHandler) override { |
| this->INHERITED::resetVaryings(varyingHandler); |
| varyingHandler->addVarying("klm", &fKLM, kHigh_GrSLPrecision); |
| varyingHandler->addVarying("grad_matrix", &fGradMatrix, kHigh_GrSLPrecision); |
| } |
| |
| void emitCubicGeometry(GrGLSLGeometryBuilder*, const char* emitVertexFn, |
| const char* wind, const char* rtAdjust) const override; |
| void emitPerVertexGeometryCode(SkString* fnBody, const char* position, const char* coverage, |
| const char* wind) const override; |
| void emitShaderCoverage(GrGLSLFragmentBuilder*, const char* outputCoverage) const override; |
| |
| protected: |
| GrGLSLGeoToFrag fKLM; |
| GrGLSLGeoToFrag fGradMatrix; |
| |
| typedef GrCCPRCubicProcessor INHERITED; |
| }; |
| |
| class GrCCPRCubicBorderProcessor : public GrCCPRCubicProcessor { |
| public: |
| GrCCPRCubicBorderProcessor(Type type) |
| : INHERITED(type) |
| , fEdgeDistanceEquation("edge_distance_equation", kVec3f_GrSLType, |
| GrShaderVar::kNonArray, kHigh_GrSLPrecision) |
| , fEdgeDistanceDerivatives("edge_distance_derivatives", kVec2f_GrSLType, |
| GrShaderVar::kNonArray, kHigh_GrSLPrecision) |
| , fEdgeSpaceTransform("edge_space_transform", kVec4f_GrSLType, GrShaderVar::kNonArray, |
| kHigh_GrSLPrecision) |
| , fKLMD(kVec4f_GrSLType) |
| , fdKLMDdx(kVec4f_GrSLType) |
| , fdKLMDdy(kVec4f_GrSLType) |
| , fEdgeSpaceCoord(kVec2f_GrSLType) {} |
| |
| void resetVaryings(GrGLSLVaryingHandler* varyingHandler) override { |
| this->INHERITED::resetVaryings(varyingHandler); |
| varyingHandler->addVarying("klmd", &fKLMD, kHigh_GrSLPrecision); |
| varyingHandler->addFlatVarying("dklmddx", &fdKLMDdx, kHigh_GrSLPrecision); |
| varyingHandler->addFlatVarying("dklmddy", &fdKLMDdy, kHigh_GrSLPrecision); |
| varyingHandler->addVarying("edge_space_coord", &fEdgeSpaceCoord, kHigh_GrSLPrecision); |
| } |
| |
| void emitCubicGeometry(GrGLSLGeometryBuilder*, const char* emitVertexFn, |
| const char* wind, const char* rtAdjust) const override; |
| void emitPerVertexGeometryCode(SkString* fnBody, const char* position, const char* coverage, |
| const char* wind) const override; |
| void emitShaderCoverage(GrGLSLFragmentBuilder*, const char* outputCoverage) const override; |
| |
| protected: |
| GrShaderVar fEdgeDistanceEquation; |
| GrShaderVar fEdgeDistanceDerivatives; |
| GrShaderVar fEdgeSpaceTransform; |
| GrGLSLGeoToFrag fKLMD; |
| GrGLSLGeoToFrag fdKLMDdx; |
| GrGLSLGeoToFrag fdKLMDdy; |
| GrGLSLGeoToFrag fEdgeSpaceCoord; |
| |
| typedef GrCCPRCubicProcessor INHERITED; |
| }; |
| |
| #endif |