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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" |
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66 virtual void emitCode(EmitArgs& args) override; | 66 virtual void emitCode(EmitArgs& args) override; |
67 | 67 |
68 private: | 68 private: |
69 typedef GrGLSLFragmentProcessor INHERITED; | 69 typedef GrGLSLFragmentProcessor INHERITED; |
70 }; | 70 }; |
71 | 71 |
72 GLDitherEffect::GLDitherEffect(const GrProcessor&) { | 72 GLDitherEffect::GLDitherEffect(const GrProcessor&) { |
73 } | 73 } |
74 | 74 |
75 void GLDitherEffect::emitCode(EmitArgs& args) { | 75 void GLDitherEffect::emitCode(EmitArgs& args) { |
76 GrGLSLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder()
; | 76 GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder; |
77 // Generate a random number based on the fragment position. For this | 77 // Generate a random number based on the fragment position. For this |
78 // random number generator, we use the "GLSL rand" function | 78 // random number generator, we use the "GLSL rand" function |
79 // 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 |
80 // the assumption that sin(<big number>) oscillates with high frequency | 80 // the assumption that sin(<big number>) oscillates with high frequency |
81 // and sampling it will generate "randomness". Since we're using this | 81 // and sampling it will generate "randomness". Since we're using this |
82 // for rendering and not cryptography it should be OK. | 82 // for rendering and not cryptography it should be OK. |
83 | 83 |
84 // 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 |
85 // it up or let it remain constant during quantization. | 85 // it up or let it remain constant during quantization. |
86 fsBuilder->codeAppendf("\t\tfloat r = " | 86 fragBuilder->codeAppendf("\t\tfloat r = " |
87 "fract(sin(dot(%s.xy ,vec2(12.9898,78.233))) * 43758.
5453);\n", | 87 "fract(sin(dot(%s.xy ,vec2(12.9898,78.233))) * 4375
8.5453);\n", |
88 fsBuilder->fragmentPosition()); | 88 fragBuilder->fragmentPosition()); |
89 fsBuilder->codeAppendf("\t\t%s = (1.0/255.0) * vec4(r, r, r, r) + %s;\n", | 89 fragBuilder->codeAppendf("\t\t%s = (1.0/255.0) * vec4(r, r, r, r) + %s;\n", |
90 args.fOutputColor, GrGLSLExpr4(args.fInputColor).c_st
r()); | 90 args.fOutputColor, GrGLSLExpr4(args.fInputColor).c_
str()); |
91 } | 91 } |
92 | 92 |
93 ////////////////////////////////////////////////////////////////////////////// | 93 ////////////////////////////////////////////////////////////////////////////// |
94 | 94 |
95 void DitherEffect::onGetGLSLProcessorKey(const GrGLSLCaps& caps, | 95 void DitherEffect::onGetGLSLProcessorKey(const GrGLSLCaps& caps, |
96 GrProcessorKeyBuilder* b) const { | 96 GrProcessorKeyBuilder* b) const { |
97 GLDitherEffect::GenKey(*this, caps, b); | 97 GLDitherEffect::GenKey(*this, caps, b); |
98 } | 98 } |
99 | 99 |
100 GrGLSLFragmentProcessor* DitherEffect::onCreateGLSLInstance() const { | 100 GrGLSLFragmentProcessor* DitherEffect::onCreateGLSLInstance() const { |
101 return new GLDitherEffect(*this); | 101 return new GLDitherEffect(*this); |
102 } | 102 } |
103 | 103 |
104 GrFragmentProcessor* GrDitherEffect::Create() { return DitherEffect::Create(); } | 104 GrFragmentProcessor* GrDitherEffect::Create() { return DitherEffect::Create(); } |
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