GrBicubicEffect.cpp revision dec61503d02862760f3c91203a698636a02c882a 
1#include "GrBicubicEffect.h"
2
3#define DS(x) SkDoubleToScalar(x)
4
5const SkScalar GrBicubicEffect::gMitchellCoefficients[16] = {
6    DS( 1.0 / 18.0), DS(-9.0 / 18.0), DS( 15.0 / 18.0), DS( -7.0 / 18.0),
7    DS(16.0 / 18.0), DS( 0.0 / 18.0), DS(-36.0 / 18.0), DS( 21.0 / 18.0),
8    DS( 1.0 / 18.0), DS( 9.0 / 18.0), DS( 27.0 / 18.0), DS(-21.0 / 18.0),
9    DS( 0.0 / 18.0), DS( 0.0 / 18.0), DS( -6.0 / 18.0), DS(  7.0 / 18.0),
10};
11
12
13class GrGLBicubicEffect : public GrGLEffect {
14public:
15    GrGLBicubicEffect(const GrBackendEffectFactory& factory,
16                      const GrDrawEffect&);
17    virtual void emitCode(GrGLShaderBuilder*,
18                          const GrDrawEffect&,
19                          EffectKey,
20                          const char* outputColor,
21                          const char* inputColor,
22                          const TransformedCoordsArray&,
23                          const TextureSamplerArray&) SK_OVERRIDE;
24
25    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
26
27private:
28    typedef GrGLUniformManager::UniformHandle        UniformHandle;
29
30    UniformHandle       fCoefficientsUni;
31    UniformHandle       fImageIncrementUni;
32
33    typedef GrGLEffect INHERITED;
34};
35
36GrGLBicubicEffect::GrGLBicubicEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&)
37    : INHERITED(factory) {
38}
39
40void GrGLBicubicEffect::emitCode(GrGLShaderBuilder* builder,
41                                 const GrDrawEffect&,
42                                 EffectKey key,
43                                 const char* outputColor,
44                                 const char* inputColor,
45                                 const TransformedCoordsArray& coords,
46                                 const TextureSamplerArray& samplers) {
47    sk_ignore_unused_variable(inputColor);
48
49    SkString coords2D = builder->ensureFSCoords2D(coords, 0);
50    fCoefficientsUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
51                                           kMat44f_GrSLType, "Coefficients");
52    fImageIncrementUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
53                                             kVec2f_GrSLType, "ImageIncrement");
54
55    const char* imgInc = builder->getUniformCStr(fImageIncrementUni);
56    const char* coeff = builder->getUniformCStr(fCoefficientsUni);
57
58    SkString cubicBlendName;
59
60    static const GrGLShaderVar gCubicBlendArgs[] = {
61        GrGLShaderVar("coefficients",  kMat44f_GrSLType),
62        GrGLShaderVar("t",             kFloat_GrSLType),
63        GrGLShaderVar("c0",            kVec4f_GrSLType),
64        GrGLShaderVar("c1",            kVec4f_GrSLType),
65        GrGLShaderVar("c2",            kVec4f_GrSLType),
66        GrGLShaderVar("c3",            kVec4f_GrSLType),
67    };
68    builder->fsEmitFunction(kVec4f_GrSLType,
69                            "cubicBlend",
70                            SK_ARRAY_COUNT(gCubicBlendArgs),
71                            gCubicBlendArgs,
72                            "\tvec4 ts = vec4(1.0, t, t * t, t * t * t);\n"
73                            "\tvec4 c = coefficients * ts;\n"
74                            "\treturn c.x * c0 + c.y * c1 + c.z * c2 + c.w * c3;\n",
75                            &cubicBlendName);
76    builder->fsCodeAppendf("\tvec2 coord = %s - %s * vec2(0.5);\n", coords2D.c_str(), imgInc);
77    // We unnormalize the coord in order to determine our fractional offset (f) within the texel
78    // We then snap coord to a texel center and renormalize. The snap prevents cases where the
79    // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
80    // double hit a texel.
81    builder->fsCodeAppendf("\tcoord /= %s;\n", imgInc);
82    builder->fsCodeAppend("\tvec2 f = fract(coord);\n");
83    builder->fsCodeAppendf("\tcoord = (coord - f + vec2(0.5)) * %s;\n", imgInc);
84    for (int y = 0; y < 4; ++y) {
85        for (int x = 0; x < 4; ++x) {
86            SkString coord;
87            coord.printf("coord + %s * vec2(%d, %d)", imgInc, x - 1, y - 1);
88            builder->fsCodeAppendf("\tvec4 s%d%d = ", x, y);
89            builder->fsAppendTextureLookup(samplers[0], coord.c_str());
90            builder->fsCodeAppend(";\n");
91        }
92        builder->fsCodeAppendf("\tvec4 s%d = %s(%s, f.x, s0%d, s1%d, s2%d, s3%d);\n", y, cubicBlendName.c_str(), coeff, y, y, y, y);
93    }
94    builder->fsCodeAppendf("\t%s = %s(%s, f.y, s0, s1, s2, s3);\n", outputColor, cubicBlendName.c_str(), coeff);
95}
96
97void GrGLBicubicEffect::setData(const GrGLUniformManager& uman,
98                                const GrDrawEffect& drawEffect) {
99    const GrBicubicEffect& effect = drawEffect.castEffect<GrBicubicEffect>();
100    GrTexture& texture = *effect.texture(0);
101    float imageIncrement[2];
102    imageIncrement[0] = 1.0f / texture.width();
103    imageIncrement[1] = 1.0f / texture.height();
104    uman.set2fv(fImageIncrementUni, 1, imageIncrement);
105    uman.setMatrix4f(fCoefficientsUni, effect.coefficients());
106}
107
108GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
109                                 const SkScalar coefficients[16])
110  : INHERITED(texture, MakeDivByTextureWHMatrix(texture)) {
111    for (int y = 0; y < 4; y++) {
112        for (int x = 0; x < 4; x++) {
113            // Convert from row-major scalars to column-major floats.
114            fCoefficients[x * 4 + y] = SkScalarToFloat(coefficients[y * 4 + x]);
115        }
116    }
117    this->setWillNotUseInputColor();
118}
119
120GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
121                                 const SkScalar coefficients[16],
122                                 const SkMatrix &matrix,
123                                 const GrTextureParams &params,
124                                 GrCoordSet coordSet)
125  : INHERITED(texture, matrix, params, coordSet) {
126    for (int y = 0; y < 4; y++) {
127        for (int x = 0; x < 4; x++) {
128            // Convert from row-major scalars to column-major floats.
129            fCoefficients[x * 4 + y] = SkScalarToFloat(coefficients[y * 4 + x]);
130        }
131    }
132    this->setWillNotUseInputColor();
133}
134
135GrBicubicEffect::~GrBicubicEffect() {
136}
137
138const GrBackendEffectFactory& GrBicubicEffect::getFactory() const {
139    return GrTBackendEffectFactory<GrBicubicEffect>::getInstance();
140}
141
142bool GrBicubicEffect::onIsEqual(const GrEffect& sBase) const {
143    const GrBicubicEffect& s = CastEffect<GrBicubicEffect>(sBase);
144    return this->textureAccess(0) == s.textureAccess(0) &&
145           !memcmp(fCoefficients, s.coefficients(), 16);
146}
147
148void GrBicubicEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
149    // FIXME:  Perhaps we can do better.
150    *validFlags = 0;
151    return;
152}
153
154GR_DEFINE_EFFECT_TEST(GrBicubicEffect);
155
156GrEffectRef* GrBicubicEffect::TestCreate(SkRandom* random,
157                                         GrContext* context,
158                                         const GrDrawTargetCaps&,
159                                         GrTexture* textures[]) {
160    int texIdx = random->nextBool() ? GrEffectUnitTest::kSkiaPMTextureIdx :
161                                      GrEffectUnitTest::kAlphaTextureIdx;
162    SkScalar coefficients[16];
163    for (int i = 0; i < 16; i++) {
164        coefficients[i] = random->nextSScalar1();
165    }
166    return GrBicubicEffect::Create(textures[texIdx], coefficients);
167}
168