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: |
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 | |