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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 GrCCPRCubicShader_DEFINED
#define GrCCPRCubicShader_DEFINED
#include "ccpr/GrCCPRCoverageProcessor.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 GrCCPRGeometry.)
*/
class GrCCPRCubicShader : public GrCCPRCoverageProcessor::Shader {
public:
enum class CubicType {
kSerpentine,
kLoop
};
protected:
GrCCPRCubicShader(CubicType cubicType) : fCubicType(cubicType) {}
void emitSetupCode(GrGLSLShaderBuilder*, const char* pts, const char* segmentId,
const char* wind, GeometryVars*) const final;
virtual void onEmitSetupCode(GrGLSLShaderBuilder*, const char* pts, const char* segmentId,
GeometryVars*) const = 0;
WindHandling onEmitVaryings(GrGLSLVaryingHandler*, SkString* code, const char* position,
const char* coverage, const char* wind) final;
virtual void onEmitVaryings(GrGLSLVaryingHandler*, SkString* code) = 0;
const CubicType fCubicType;
GrShaderVar fKLMMatrix{"klm_matrix", kFloat3x3_GrSLType};
GrShaderVar fEdgeDistanceEquation{"edge_distance_equation", kFloat3_GrSLType};
GrGLSLGeoToFrag fKLMD{kFloat4_GrSLType};
};
class GrCCPRCubicHullShader : public GrCCPRCubicShader {
public:
GrCCPRCubicHullShader(CubicType cubicType) : GrCCPRCubicShader(cubicType) {}
private:
GeometryType getGeometryType() const override { return GeometryType::kHull; }
int getNumSegments() const override { return 4; } // 4 wedges.
void onEmitSetupCode(GrGLSLShaderBuilder*, const char* pts, const char* wedgeId,
GeometryVars*) const override;
void onEmitVaryings(GrGLSLVaryingHandler*, SkString* code) override;
void onEmitFragmentCode(GrGLSLPPFragmentBuilder*, const char* outputCoverage) const override;
GrGLSLGeoToFrag fGradMatrix{kFloat2x2_GrSLType};
};
class GrCCPRCubicCornerShader : public GrCCPRCubicShader {
public:
GrCCPRCubicCornerShader(CubicType cubicType) : GrCCPRCubicShader(cubicType) {}
private:
GeometryType getGeometryType() const override { return GeometryType::kCorners; }
int getNumSegments() const override { return 2; } // 2 corners.
void onEmitSetupCode(GrGLSLShaderBuilder*, const char* pts, const char* cornerId,
GeometryVars*) const override;
void onEmitVaryings(GrGLSLVaryingHandler*, SkString* code) override;
void onEmitFragmentCode(GrGLSLPPFragmentBuilder*, const char* outputCoverage) const override;
GrGLSLGeoToFrag fdKLMDdx{kFloat4_GrSLType};
GrGLSLGeoToFrag fdKLMDdy{kFloat4_GrSLType};
};
#endif
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