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- /*
- * 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 GrCCCubicShader_DEFINED
- #define GrCCCubicShader_DEFINED
- #include "src/gpu/ccpr/GrCCCoverageProcessor.h"
- /**
- * 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 provided curve segments must be convex, monotonic with respect to the vector of their closing
- * edge [P3 - P0], and must not contain or be near any inflection points or loop intersections.
- * (Use GrCCGeometry::cubicTo().)
- */
- class GrCCCubicShader : public GrCCCoverageProcessor::Shader {
- public:
- void emitSetupCode(
- GrGLSLVertexGeoBuilder*, const char* pts, const char** outHull4) const override;
- void onEmitVaryings(
- GrGLSLVaryingHandler*, GrGLSLVarying::Scope, SkString* code, const char* position,
- const char* coverage, const char* cornerCoverage, const char* wind) override;
- void emitFragmentCoverageCode(
- GrGLSLFPFragmentBuilder*, const char* outputCoverage) const override;
- void emitSampleMaskCode(GrGLSLFPFragmentBuilder*) const override;
- private:
- void calcHullCoverage(SkString* code, const char* klmAndEdge, const char* gradMatrix,
- const char* outputCoverage) const;
- const GrShaderVar fKLMMatrix{"klm_matrix", kFloat3x3_GrSLType};
- GrGLSLVarying fKLM_fEdge;
- GrGLSLVarying fGradMatrix;
- GrGLSLVarying fCornerCoverage;
- };
- #endif
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