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 GrCCQuadraticShader_DEFINED
9#define GrCCQuadraticShader_DEFINED
10
11#include "src/gpu/ccpr/GrCCCoverageProcessor.h"
12
13/**
14 * This class renders the coverage of closed quadratic 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::quadraticTo().)
22 */
23class GrCCQuadraticShader : public GrCCCoverageProcessor::Shader {
24public:
25 void emitSetupCode(
26 GrGLSLVertexGeoBuilder*, const char* pts, const char** outHull4) const override;
27
28 void onEmitVaryings(
29 GrGLSLVaryingHandler*, GrGLSLVarying::Scope, SkString* code, const char* position,
30 const char* coverage, const char* cornerCoverage, const char* wind) override;
31
32 void emitFragmentCoverageCode(
33 GrGLSLFPFragmentBuilder*, const char* outputCoverage) const override;
34
35 void emitSampleMaskCode(GrGLSLFPFragmentBuilder*) const override;
36
37private:
38 void calcHullCoverage(SkString* code, const char* coordAndGrad, const char* d,
39 const char* outputCoverage) const;
40
41 const GrShaderVar fQCoordMatrix{"qcoord_matrix", kFloat2x2_GrSLType};
42 const GrShaderVar fQCoord0{"qcoord0", kFloat2_GrSLType};
43 GrGLSLVarying fCoord_fGrad;
44 GrGLSLVarying fEdge_fWind_fCorner;
45};
46
47#endif
48