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 | */ |
23 | class GrCCQuadraticShader : public GrCCCoverageProcessor::Shader { |
24 | public: |
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 | |
37 | private: |
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 | |