GrConvolutionEffect.cpp revision 6f261bed0252e3f3caa595798364e0bf12a2573a 
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 GrGLLegacyProgramStage {
19public:
20    GrGLConvolutionEffect(const GrProgramStageFactory& factory,
21                          const GrEffect& 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, const GrEffect&) SK_OVERRIDE;
32
33    static inline StageKey GenKey(const GrEffect&, const GrGLCaps&);
34
35private:
36    int width() const { return Gr1DKernelEffect::WidthFromRadius(fRadius); }
37
38    int             fRadius;
39    UniformHandle   fKernelUni;
40    UniformHandle   fImageIncrementUni;
41
42    typedef GrGLLegacyProgramStage INHERITED;
43};
44
45GrGLConvolutionEffect::GrGLConvolutionEffect(const GrProgramStageFactory& factory,
46                                             const GrEffect& stage)
47    : INHERITED(factory)
48    , fKernelUni(kInvalidUniformHandle)
49    , fImageIncrementUni(kInvalidUniformHandle) {
50    const GrConvolutionEffect& c =
51        static_cast<const GrConvolutionEffect&>(stage);
52    fRadius = c.radius();
53}
54
55void GrGLConvolutionEffect::setupVariables(GrGLShaderBuilder* builder) {
56    fImageIncrementUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
57                                             kVec2f_GrSLType, "ImageIncrement");
58    fKernelUni = builder->addUniformArray(GrGLShaderBuilder::kFragment_ShaderType,
59                                          kFloat_GrSLType, "Kernel", this->width());
60}
61
62void GrGLConvolutionEffect::emitFS(GrGLShaderBuilder* builder,
63                                   const char* outputColor,
64                                   const char* inputColor,
65                                   const TextureSamplerArray& samplers) {
66    SkString* code = &builder->fFSCode;
67
68    code->appendf("\t\t%s = vec4(0, 0, 0, 0);\n", outputColor);
69
70    int width = this ->width();
71    const GrGLShaderVar& kernel = builder->getUniformVariable(fKernelUni);
72    const char* imgInc = builder->getUniformCStr(fImageIncrementUni);
73
74    code->appendf("\t\tvec2 coord = %s - %d.0 * %s;\n",
75                  builder->defaultTexCoordsName(), fRadius, imgInc);
76
77    // Manually unroll loop because some drivers don't; yields 20-30% speedup.
78    for (int i = 0; i < width; i++) {
79        SkString index;
80        SkString kernelIndex;
81        index.appendS32(i);
82        kernel.appendArrayAccess(index.c_str(), &kernelIndex);
83        code->appendf("\t\t%s += ", outputColor);
84        builder->appendTextureLookup(&builder->fFSCode, samplers[0], "coord");
85        code->appendf(" * %s;\n", kernelIndex.c_str());
86        code->appendf("\t\tcoord += %s;\n", imgInc);
87    }
88    GrGLSLMulVarBy4f(&builder->fFSCode, 2, outputColor, inputColor);
89}
90
91void GrGLConvolutionEffect::setData(const GrGLUniformManager& uman, const GrEffect& data) {
92    const GrConvolutionEffect& conv =
93        static_cast<const GrConvolutionEffect&>(data);
94    GrTexture& texture = *data.texture(0);
95    // the code we generated was for a specific kernel radius
96    GrAssert(conv.radius() == fRadius);
97    float imageIncrement[2] = { 0 };
98    switch (conv.direction()) {
99        case Gr1DKernelEffect::kX_Direction:
100            imageIncrement[0] = 1.0f / texture.width();
101            break;
102        case Gr1DKernelEffect::kY_Direction:
103            imageIncrement[1] = 1.0f / texture.height();
104            break;
105        default:
106            GrCrash("Unknown filter direction.");
107    }
108    uman.set2fv(fImageIncrementUni, 0, 1, imageIncrement);
109    uman.set1fv(fKernelUni, 0, this->width(), conv.kernel());
110}
111
112GrGLProgramStage::StageKey GrGLConvolutionEffect::GenKey(const GrEffect& s,
113                                                         const GrGLCaps& caps) {
114    return static_cast<const GrConvolutionEffect&>(s).radius();
115}
116
117///////////////////////////////////////////////////////////////////////////////
118
119GrConvolutionEffect::GrConvolutionEffect(GrTexture* texture,
120                                         Direction direction,
121                                         int radius,
122                                         const float* kernel)
123    : Gr1DKernelEffect(texture, direction, radius) {
124    GrAssert(radius <= kMaxKernelRadius);
125    int width = this->width();
126    if (NULL != kernel) {
127        for (int i = 0; i < width; i++) {
128            fKernel[i] = kernel[i];
129        }
130    }
131}
132
133GrConvolutionEffect::GrConvolutionEffect(GrTexture* texture,
134                                         Direction direction,
135                                         int radius,
136                                         float gaussianSigma)
137    : Gr1DKernelEffect(texture, direction, radius) {
138    GrAssert(radius <= kMaxKernelRadius);
139    int width = this->width();
140
141    float sum = 0.0f;
142    float denom = 1.0f / (2.0f * gaussianSigma * gaussianSigma);
143    for (int i = 0; i < width; ++i) {
144        float x = static_cast<float>(i - this->radius());
145        // Note that the constant term (1/(sqrt(2*pi*sigma^2)) of the Gaussian
146        // is dropped here, since we renormalize the kernel below.
147        fKernel[i] = sk_float_exp(- x * x * denom);
148        sum += fKernel[i];
149    }
150    // Normalize the kernel
151    float scale = 1.0f / sum;
152    for (int i = 0; i < width; ++i) {
153        fKernel[i] *= scale;
154    }
155}
156
157GrConvolutionEffect::~GrConvolutionEffect() {
158}
159
160const GrProgramStageFactory& GrConvolutionEffect::getFactory() const {
161    return GrTProgramStageFactory<GrConvolutionEffect>::getInstance();
162}
163
164bool GrConvolutionEffect::isEqual(const GrEffect& sBase) const {
165     const GrConvolutionEffect& s =
166        static_cast<const GrConvolutionEffect&>(sBase);
167    return (INHERITED::isEqual(sBase) &&
168            this->radius() == s.radius() &&
169            this->direction() == s.direction() &&
170            0 == memcmp(fKernel, s.fKernel, this->width() * sizeof(float)));
171}
172
173///////////////////////////////////////////////////////////////////////////////
174
175GR_DEFINE_CUSTOM_STAGE_TEST(GrConvolutionEffect);
176
177GrEffect* GrConvolutionEffect::TestCreate(SkRandom* random,
178                                          GrContext* context,
179                                          GrTexture* textures[]) {
180    int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
181                                      GrEffectUnitTest::kAlphaTextureIdx;
182    Direction dir = random->nextBool() ? kX_Direction : kY_Direction;
183    int radius = random->nextRangeU(1, kMaxKernelRadius);
184    float kernel[kMaxKernelRadius];
185    for (int i = 0; i < kMaxKernelRadius; ++i) {
186        kernel[i] = random->nextSScalar1();
187    }
188
189    return SkNEW_ARGS(GrConvolutionEffect, (textures[texIdx], dir, radius, kernel));
190}
191
192