GrConvolutionEffect.cpp revision d3353646c31ccb90cc43727ef0fa7869b4e4fe07 
1/*
2 * Copyright 2012 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#include "GrConvolutionEffect.h"
9#include "gl/GrGLProgramStage.h"
10#include "gl/GrGLSL.h"
11#include "gl/GrGLTexture.h"
12#include "GrProgramStageFactory.h"
13
14// For brevity
15typedef GrGLUniformManager::UniformHandle UniformHandle;
16static const UniformHandle kInvalidUniformHandle = GrGLUniformManager::kInvalidUniformHandle;
17
18class GrGLConvolutionEffect : public GrGLProgramStage {
19public:
20    GrGLConvolutionEffect(const GrProgramStageFactory& factory,
21                          const GrCustomStage& stage);
22
23    virtual void setupVariables(GrGLShaderBuilder* builder) SK_OVERRIDE;
24    virtual void emitVS(GrGLShaderBuilder* builder,
25                        const char* vertexCoords) SK_OVERRIDE {};
26    virtual void emitFS(GrGLShaderBuilder* builder,
27                        const char* outputColor,
28                        const char* inputColor,
29                        const TextureSamplerArray&) SK_OVERRIDE;
30
31    virtual void setData(const GrGLUniformManager& uman,
32                         const GrCustomStage&,
33                         const GrRenderTarget*,
34                         int stageNum) SK_OVERRIDE;
35
36    static inline StageKey GenKey(const GrCustomStage&, const GrGLCaps&);
37
38private:
39    int width() const { return Gr1DKernelEffect::WidthFromRadius(fRadius); }
40
41    int             fRadius;
42    UniformHandle   fKernelUni;
43    UniformHandle   fImageIncrementUni;
44
45    typedef GrGLProgramStage INHERITED;
46};
47
48GrGLConvolutionEffect::GrGLConvolutionEffect(const GrProgramStageFactory& factory,
49                                             const GrCustomStage& stage)
50    : GrGLProgramStage(factory)
51    , fKernelUni(kInvalidUniformHandle)
52    , fImageIncrementUni(kInvalidUniformHandle) {
53    const GrConvolutionEffect& c =
54        static_cast<const GrConvolutionEffect&>(stage);
55    fRadius = c.radius();
56}
57
58void GrGLConvolutionEffect::setupVariables(GrGLShaderBuilder* builder) {
59    fImageIncrementUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
60                                             kVec2f_GrSLType, "ImageIncrement");
61    fKernelUni = builder->addUniformArray(GrGLShaderBuilder::kFragment_ShaderType,
62                                          kFloat_GrSLType, "Kernel", this->width());
63}
64
65void GrGLConvolutionEffect::emitFS(GrGLShaderBuilder* builder,
66                                   const char* outputColor,
67                                   const char* inputColor,
68                                   const TextureSamplerArray& samplers) {
69    SkString* code = &builder->fFSCode;
70
71    code->appendf("\t\t%s = vec4(0, 0, 0, 0);\n", outputColor);
72
73    int width = this ->width();
74    const GrGLShaderVar& kernel = builder->getUniformVariable(fKernelUni);
75    const char* imgInc = builder->getUniformCStr(fImageIncrementUni);
76
77    code->appendf("\t\tvec2 coord = %s - %d.0 * %s;\n",
78                  builder->defaultTexCoordsName(), fRadius, imgInc);
79
80    // Manually unroll loop because some drivers don't; yields 20-30% speedup.
81    for (int i = 0; i < width; i++) {
82        SkString index;
83        SkString kernelIndex;
84        index.appendS32(i);
85        kernel.appendArrayAccess(index.c_str(), &kernelIndex);
86        code->appendf("\t\t%s += ", outputColor);
87        builder->appendTextureLookup(&builder->fFSCode, samplers[0], "coord");
88        code->appendf(" * %s;\n", kernelIndex.c_str());
89        code->appendf("\t\tcoord += %s;\n", imgInc);
90    }
91    GrGLSLMulVarBy4f(&builder->fFSCode, 2, outputColor, inputColor);
92}
93
94void GrGLConvolutionEffect::setData(const GrGLUniformManager& uman,
95                                    const GrCustomStage& data,
96                                    const GrRenderTarget*,
97                                    int stageNum) {
98    const GrConvolutionEffect& conv =
99        static_cast<const GrConvolutionEffect&>(data);
100    GrTexture& texture = *data.texture(0);
101    // the code we generated was for a specific kernel radius
102    GrAssert(conv.radius() == fRadius);
103    float imageIncrement[2] = { 0 };
104    switch (conv.direction()) {
105        case Gr1DKernelEffect::kX_Direction:
106            imageIncrement[0] = 1.0f / texture.width();
107            break;
108        case Gr1DKernelEffect::kY_Direction:
109            imageIncrement[1] = 1.0f / texture.height();
110            break;
111        default:
112            GrCrash("Unknown filter direction.");
113    }
114    uman.set2fv(fImageIncrementUni, 0, 1, imageIncrement);
115    uman.set1fv(fKernelUni, 0, this->width(), conv.kernel());
116}
117
118GrGLProgramStage::StageKey GrGLConvolutionEffect::GenKey(const GrCustomStage& s,
119                                                         const GrGLCaps& caps) {
120    return static_cast<const GrConvolutionEffect&>(s).radius();
121}
122
123///////////////////////////////////////////////////////////////////////////////
124
125GrConvolutionEffect::GrConvolutionEffect(GrTexture* texture,
126                                         Direction direction,
127                                         int radius,
128                                         const float* kernel)
129    : Gr1DKernelEffect(texture, direction, radius) {
130    GrAssert(radius <= kMaxKernelRadius);
131    int width = this->width();
132    if (NULL != kernel) {
133        for (int i = 0; i < width; i++) {
134            fKernel[i] = kernel[i];
135        }
136    }
137}
138
139GrConvolutionEffect::GrConvolutionEffect(GrTexture* texture,
140                                         Direction direction,
141                                         int radius,
142                                         float gaussianSigma)
143    : Gr1DKernelEffect(texture, direction, radius) {
144    GrAssert(radius <= kMaxKernelRadius);
145    int width = this->width();
146
147    float sum = 0.0f;
148    float denom = 1.0f / (2.0f * gaussianSigma * gaussianSigma);
149    for (int i = 0; i < width; ++i) {
150        float x = static_cast<float>(i - this->radius());
151        // Note that the constant term (1/(sqrt(2*pi*sigma^2)) of the Gaussian
152        // is dropped here, since we renormalize the kernel below.
153        fKernel[i] = sk_float_exp(- x * x * denom);
154        sum += fKernel[i];
155    }
156    // Normalize the kernel
157    float scale = 1.0f / sum;
158    for (int i = 0; i < width; ++i) {
159        fKernel[i] *= scale;
160    }
161}
162
163GrConvolutionEffect::~GrConvolutionEffect() {
164}
165
166const GrProgramStageFactory& GrConvolutionEffect::getFactory() const {
167    return GrTProgramStageFactory<GrConvolutionEffect>::getInstance();
168}
169
170bool GrConvolutionEffect::isEqual(const GrCustomStage& sBase) const {
171     const GrConvolutionEffect& s =
172        static_cast<const GrConvolutionEffect&>(sBase);
173    return (INHERITED::isEqual(sBase) &&
174            this->radius() == s.radius() &&
175            this->direction() == s.direction() &&
176            0 == memcmp(fKernel, s.fKernel, this->width() * sizeof(float)));
177}
178
179///////////////////////////////////////////////////////////////////////////////
180
181GR_DEFINE_CUSTOM_STAGE_TEST(GrConvolutionEffect);
182
183GrCustomStage* GrConvolutionEffect::TestCreate(SkRandom* random,
184                                              GrContext* context,
185                                              GrTexture* textures[]) {
186    int texIdx = random->nextBool() ? GrCustomStageUnitTest::kSkiaPMTextureIdx :
187                                      GrCustomStageUnitTest::kAlphaTextureIdx;
188    Direction dir = random->nextBool() ? kX_Direction : kY_Direction;
189    int radius = random->nextRangeU(1, kMaxKernelRadius);
190    float kernel[kMaxKernelRadius];
191    for (int i = 0; i < kMaxKernelRadius; ++i) {
192        kernel[i] = random->nextSScalar1();
193    }
194
195    return SkNEW_ARGS(GrConvolutionEffect, (textures[texIdx], dir, radius, kernel));
196}
197
198