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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" |
| (...skipping 55 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
| 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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