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1 /* | 1 /* |
2 * Copyright 2014 Google Inc. | 2 * Copyright 2014 Google Inc. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license that can be | 4 * Use of this source code is governed by a BSD-style license that can be |
5 * found in the LICENSE file. | 5 * found in the LICENSE file. |
6 */ | 6 */ |
7 | 7 |
8 #include "GrDitherEffect.h" | 8 #include "GrDitherEffect.h" |
9 #include "GrFragmentProcessor.h" | 9 #include "GrFragmentProcessor.h" |
10 #include "GrInvariantOutput.h" | 10 #include "GrInvariantOutput.h" |
11 #include "SkRect.h" | 11 #include "SkRect.h" |
12 #include "gl/GrGLFragmentProcessor.h" | 12 #include "gl/GrGLFragmentProcessor.h" |
13 #include "gl/builders/GrGLProgramBuilder.h" | 13 #include "glsl/GrGLSLFragmentShaderBuilder.h" |
| 14 #include "glsl/GrGLSLProgramBuilder.h" |
14 | 15 |
15 ////////////////////////////////////////////////////////////////////////////// | 16 ////////////////////////////////////////////////////////////////////////////// |
16 | 17 |
17 class DitherEffect : public GrFragmentProcessor { | 18 class DitherEffect : public GrFragmentProcessor { |
18 public: | 19 public: |
19 static GrFragmentProcessor* Create() { | 20 static GrFragmentProcessor* Create() { |
20 return new DitherEffect; | 21 return new DitherEffect; |
21 } | 22 } |
22 | 23 |
23 virtual ~DitherEffect() {}; | 24 virtual ~DitherEffect() {}; |
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65 virtual void emitCode(EmitArgs& args) override; | 66 virtual void emitCode(EmitArgs& args) override; |
66 | 67 |
67 private: | 68 private: |
68 typedef GrGLFragmentProcessor INHERITED; | 69 typedef GrGLFragmentProcessor INHERITED; |
69 }; | 70 }; |
70 | 71 |
71 GLDitherEffect::GLDitherEffect(const GrProcessor&) { | 72 GLDitherEffect::GLDitherEffect(const GrProcessor&) { |
72 } | 73 } |
73 | 74 |
74 void GLDitherEffect::emitCode(EmitArgs& args) { | 75 void GLDitherEffect::emitCode(EmitArgs& args) { |
75 GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder(); | 76 GrGLSLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder()
; |
76 // Generate a random number based on the fragment position. For this | 77 // Generate a random number based on the fragment position. For this |
77 // random number generator, we use the "GLSL rand" function | 78 // random number generator, we use the "GLSL rand" function |
78 // that seems to be floating around on the internet. It works under | 79 // that seems to be floating around on the internet. It works under |
79 // the assumption that sin(<big number>) oscillates with high frequency | 80 // the assumption that sin(<big number>) oscillates with high frequency |
80 // and sampling it will generate "randomness". Since we're using this | 81 // and sampling it will generate "randomness". Since we're using this |
81 // for rendering and not cryptography it should be OK. | 82 // for rendering and not cryptography it should be OK. |
82 | 83 |
83 // For each channel c, add the random offset to the pixel to either bump | 84 // For each channel c, add the random offset to the pixel to either bump |
84 // it up or let it remain constant during quantization. | 85 // it up or let it remain constant during quantization. |
85 fsBuilder->codeAppendf("\t\tfloat r = " | 86 fsBuilder->codeAppendf("\t\tfloat r = " |
86 "fract(sin(dot(%s.xy ,vec2(12.9898,78.233))) * 43758.
5453);\n", | 87 "fract(sin(dot(%s.xy ,vec2(12.9898,78.233))) * 43758.
5453);\n", |
87 fsBuilder->fragmentPosition()); | 88 fsBuilder->fragmentPosition()); |
88 fsBuilder->codeAppendf("\t\t%s = (1.0/255.0) * vec4(r, r, r, r) + %s;\n", | 89 fsBuilder->codeAppendf("\t\t%s = (1.0/255.0) * vec4(r, r, r, r) + %s;\n", |
89 args.fOutputColor, GrGLSLExpr4(args.fInputColor).c_st
r()); | 90 args.fOutputColor, GrGLSLExpr4(args.fInputColor).c_st
r()); |
90 } | 91 } |
91 | 92 |
92 ////////////////////////////////////////////////////////////////////////////// | 93 ////////////////////////////////////////////////////////////////////////////// |
93 | 94 |
94 void DitherEffect::onGetGLProcessorKey(const GrGLSLCaps& caps, | 95 void DitherEffect::onGetGLProcessorKey(const GrGLSLCaps& caps, |
95 GrProcessorKeyBuilder* b) const { | 96 GrProcessorKeyBuilder* b) const { |
96 GLDitherEffect::GenKey(*this, caps, b); | 97 GLDitherEffect::GenKey(*this, caps, b); |
97 } | 98 } |
98 | 99 |
99 GrGLFragmentProcessor* DitherEffect::onCreateGLInstance() const { | 100 GrGLFragmentProcessor* DitherEffect::onCreateGLInstance() const { |
100 return new GLDitherEffect(*this); | 101 return new GLDitherEffect(*this); |
101 } | 102 } |
102 | 103 |
103 GrFragmentProcessor* GrDitherEffect::Create() { return DitherEffect::Create(); } | 104 GrFragmentProcessor* GrDitherEffect::Create() { return DitherEffect::Create(); } |
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