1 /* 2 * Copyright 2017 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef GrCCCubicShader_DEFINED 9 #define GrCCCubicShader_DEFINED 10 11 #include "src/gpu/ccpr/GrCCCoverageProcessor.h" 12 13 /** 14 * This class renders the coverage of convex closed cubic segments using the techniques outlined in 15 * "Resolution Independent Curve Rendering using Programmable Graphics Hardware" by Charles Loop and 16 * Jim Blinn: 17 * 18 * https://www.microsoft.com/en-us/research/wp-content/uploads/2005/01/p1000-loop.pdf 19 * 20 * The provided curve segments must be convex, monotonic with respect to the vector of their closing 21 * edge [P3 - P0], and must not contain or be near any inflection points or loop intersections. 22 * (Use GrCCGeometry::cubicTo().) 23 */ 24 class GrCCCubicShader : public GrCCCoverageProcessor::Shader { 25 public: 26 void emitSetupCode( 27 GrGLSLVertexGeoBuilder*, const char* pts, const char** outHull4) const override; 28 29 void onEmitVaryings( 30 GrGLSLVaryingHandler*, GrGLSLVarying::Scope, SkString* code, const char* position, 31 const char* coverage, const char* cornerCoverage, const char* wind) override; 32 33 void emitFragmentCoverageCode( 34 GrGLSLFPFragmentBuilder*, const char* outputCoverage) const override; 35 36 void emitSampleMaskCode(GrGLSLFPFragmentBuilder*) const override; 37 38 private: 39 void calcHullCoverage(SkString* code, const char* klmAndEdge, const char* gradMatrix, 40 const char* outputCoverage) const; 41 42 const GrShaderVar fKLMMatrix{"klm_matrix", kFloat3x3_GrSLType}; 43 GrGLSLVarying fKLM_fEdge; 44 GrGLSLVarying fGradMatrix; 45 GrGLSLVarying fCornerCoverage; 46 }; 47 48 #endif 49