1 /* 2 * Copyright 2018 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 GrCCConicShader_DEFINED 9 #define GrCCConicShader_DEFINED 10 11 #include "src/gpu/ccpr/GrCCCoverageProcessor.h" 12 13 /** 14 * This class renders the coverage of closed conic curves 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 curves must be monotonic with respect to the vector of their closing edge [P2 - P0]. 21 * (Use GrCCGeometry::conicTo().) 22 */ 23 class GrCCConicShader : public GrCCCoverageProcessor::Shader { 24 public: calculatesOwnEdgeCoverage()25 bool calculatesOwnEdgeCoverage() const override { return true; } 26 27 void emitSetupCode( 28 GrGLSLVertexGeoBuilder*, const char* pts, const char** outHull4) const override; 29 30 void onEmitVaryings( 31 GrGLSLVaryingHandler*, GrGLSLVarying::Scope, SkString* code, const char* position, 32 const char* coverage, const char* cornerCoverage, const char* wind) override; 33 34 void emitFragmentCoverageCode( 35 GrGLSLFPFragmentBuilder*, const char* outputCoverage) const override; 36 37 void emitSampleMaskCode(GrGLSLFPFragmentBuilder*) const override; 38 39 private: 40 void calcHullCoverage(SkString* code, const char* klm, const char* grad, 41 const char* outputCoverage) const; 42 43 const GrShaderVar fKLMMatrix{"klm_matrix", kFloat3x3_GrSLType}; 44 const GrShaderVar fControlPoint{"control_point", kFloat2_GrSLType}; 45 GrGLSLVarying fKLM_fWind; 46 GrGLSLVarying fGrad_fCorner; 47 }; 48 49 #endif 50