1/*
2 * Copyright 2014 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 "gl/builders/GrGLProgramBuilder.h"
9#include "GrBicubicEffect.h"
10
11
12#define DS(x) SkDoubleToScalar(x)
13
14const SkScalar GrBicubicEffect::gMitchellCoefficients[16] = {
15    DS( 1.0 / 18.0), DS(-9.0 / 18.0), DS( 15.0 / 18.0), DS( -7.0 / 18.0),
16    DS(16.0 / 18.0), DS( 0.0 / 18.0), DS(-36.0 / 18.0), DS( 21.0 / 18.0),
17    DS( 1.0 / 18.0), DS( 9.0 / 18.0), DS( 27.0 / 18.0), DS(-21.0 / 18.0),
18    DS( 0.0 / 18.0), DS( 0.0 / 18.0), DS( -6.0 / 18.0), DS(  7.0 / 18.0),
19};
20
21
22class GrGLBicubicEffect : public GrGLFragmentProcessor {
23public:
24    GrGLBicubicEffect(const GrBackendProcessorFactory& factory,
25                      const GrProcessor&);
26
27    virtual void emitCode(GrGLProgramBuilder*,
28                          const GrFragmentProcessor&,
29                          const GrProcessorKey&,
30                          const char* outputColor,
31                          const char* inputColor,
32                          const TransformedCoordsArray&,
33                          const TextureSamplerArray&) SK_OVERRIDE;
34
35    virtual void setData(const GrGLProgramDataManager&, const GrProcessor&) SK_OVERRIDE;
36
37    static inline void GenKey(const GrProcessor& effect, const GrGLCaps&,
38                              GrProcessorKeyBuilder* b) {
39        const GrTextureDomain& domain = effect.cast<GrBicubicEffect>().domain();
40        b->add32(GrTextureDomain::GLDomain::DomainKey(domain));
41    }
42
43private:
44    typedef GrGLProgramDataManager::UniformHandle UniformHandle;
45
46    UniformHandle               fCoefficientsUni;
47    UniformHandle               fImageIncrementUni;
48    GrTextureDomain::GLDomain   fDomain;
49
50    typedef GrGLFragmentProcessor INHERITED;
51};
52
53GrGLBicubicEffect::GrGLBicubicEffect(const GrBackendProcessorFactory& factory, const GrProcessor&)
54    : INHERITED(factory) {
55}
56
57void GrGLBicubicEffect::emitCode(GrGLProgramBuilder* builder,
58                                 const GrFragmentProcessor& effect,
59                                 const GrProcessorKey& key,
60                                 const char* outputColor,
61                                 const char* inputColor,
62                                 const TransformedCoordsArray& coords,
63                                 const TextureSamplerArray& samplers) {
64    const GrTextureDomain& domain = effect.cast<GrBicubicEffect>().domain();
65
66    fCoefficientsUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
67                                           kMat44f_GrSLType, "Coefficients");
68    fImageIncrementUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
69                                             kVec2f_GrSLType, "ImageIncrement");
70
71    const char* imgInc = builder->getUniformCStr(fImageIncrementUni);
72    const char* coeff = builder->getUniformCStr(fCoefficientsUni);
73
74    SkString cubicBlendName;
75
76    static const GrGLShaderVar gCubicBlendArgs[] = {
77        GrGLShaderVar("coefficients",  kMat44f_GrSLType),
78        GrGLShaderVar("t",             kFloat_GrSLType),
79        GrGLShaderVar("c0",            kVec4f_GrSLType),
80        GrGLShaderVar("c1",            kVec4f_GrSLType),
81        GrGLShaderVar("c2",            kVec4f_GrSLType),
82        GrGLShaderVar("c3",            kVec4f_GrSLType),
83    };
84    GrGLFragmentShaderBuilder* fsBuilder = builder->getFragmentShaderBuilder();
85    SkString coords2D = fsBuilder->ensureFSCoords2D(coords, 0);
86    fsBuilder->emitFunction(kVec4f_GrSLType,
87                            "cubicBlend",
88                            SK_ARRAY_COUNT(gCubicBlendArgs),
89                            gCubicBlendArgs,
90                            "\tvec4 ts = vec4(1.0, t, t * t, t * t * t);\n"
91                            "\tvec4 c = coefficients * ts;\n"
92                            "\treturn c.x * c0 + c.y * c1 + c.z * c2 + c.w * c3;\n",
93                            &cubicBlendName);
94    fsBuilder->codeAppendf("\tvec2 coord = %s - %s * vec2(0.5);\n", coords2D.c_str(), imgInc);
95    // We unnormalize the coord in order to determine our fractional offset (f) within the texel
96    // We then snap coord to a texel center and renormalize. The snap prevents cases where the
97    // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
98    // double hit a texel.
99    fsBuilder->codeAppendf("\tcoord /= %s;\n", imgInc);
100    fsBuilder->codeAppend("\tvec2 f = fract(coord);\n");
101    fsBuilder->codeAppendf("\tcoord = (coord - f + vec2(0.5)) * %s;\n", imgInc);
102    fsBuilder->codeAppend("\tvec4 rowColors[4];\n");
103    for (int y = 0; y < 4; ++y) {
104        for (int x = 0; x < 4; ++x) {
105            SkString coord;
106            coord.printf("coord + %s * vec2(%d, %d)", imgInc, x - 1, y - 1);
107            SkString sampleVar;
108            sampleVar.printf("rowColors[%d]", x);
109            fDomain.sampleTexture(fsBuilder, domain, sampleVar.c_str(), coord, samplers[0]);
110        }
111        fsBuilder->codeAppendf("\tvec4 s%d = %s(%s, f.x, rowColors[0], rowColors[1], rowColors[2], rowColors[3]);\n", y, cubicBlendName.c_str(), coeff);
112    }
113    SkString bicubicColor;
114    bicubicColor.printf("%s(%s, f.y, s0, s1, s2, s3)", cubicBlendName.c_str(), coeff);
115    fsBuilder->codeAppendf("\t%s = %s;\n", outputColor, (GrGLSLExpr4(bicubicColor.c_str()) * GrGLSLExpr4(inputColor)).c_str());
116}
117
118void GrGLBicubicEffect::setData(const GrGLProgramDataManager& pdman,
119                                const GrProcessor& processor) {
120    const GrBicubicEffect& bicubicEffect = processor.cast<GrBicubicEffect>();
121    const GrTexture& texture = *processor.texture(0);
122    float imageIncrement[2];
123    imageIncrement[0] = 1.0f / texture.width();
124    imageIncrement[1] = 1.0f / texture.height();
125    pdman.set2fv(fImageIncrementUni, 1, imageIncrement);
126    pdman.setMatrix4f(fCoefficientsUni, bicubicEffect.coefficients());
127    fDomain.setData(pdman, bicubicEffect.domain(), texture.origin());
128}
129
130static inline void convert_row_major_scalar_coeffs_to_column_major_floats(float dst[16],
131                                                                          const SkScalar src[16]) {
132    for (int y = 0; y < 4; y++) {
133        for (int x = 0; x < 4; x++) {
134            dst[x * 4 + y] = SkScalarToFloat(src[y * 4 + x]);
135        }
136    }
137}
138
139GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
140                                 const SkScalar coefficients[16],
141                                 const SkMatrix &matrix,
142                                 const SkShader::TileMode tileModes[2])
143  : INHERITED(texture, matrix, GrTextureParams(tileModes, GrTextureParams::kNone_FilterMode))
144  , fDomain(GrTextureDomain::IgnoredDomain()) {
145    convert_row_major_scalar_coeffs_to_column_major_floats(fCoefficients, coefficients);
146}
147
148GrBicubicEffect::GrBicubicEffect(GrTexture* texture,
149                                 const SkScalar coefficients[16],
150                                 const SkMatrix &matrix,
151                                 const SkRect& domain)
152  : INHERITED(texture, matrix, GrTextureParams(SkShader::kClamp_TileMode,
153                                               GrTextureParams::kNone_FilterMode))
154  , fDomain(domain, GrTextureDomain::kClamp_Mode) {
155    convert_row_major_scalar_coeffs_to_column_major_floats(fCoefficients, coefficients);
156}
157
158GrBicubicEffect::~GrBicubicEffect() {
159}
160
161const GrBackendFragmentProcessorFactory& GrBicubicEffect::getFactory() const {
162    return GrTBackendFragmentProcessorFactory<GrBicubicEffect>::getInstance();
163}
164
165bool GrBicubicEffect::onIsEqual(const GrProcessor& sBase) const {
166    const GrBicubicEffect& s = sBase.cast<GrBicubicEffect>();
167    return this->textureAccess(0) == s.textureAccess(0) &&
168           !memcmp(fCoefficients, s.coefficients(), 16) &&
169           fDomain == s.fDomain;
170}
171
172void GrBicubicEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
173    // FIXME: Perhaps we can do better.
174    *validFlags = 0;
175    return;
176}
177
178GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrBicubicEffect);
179
180GrFragmentProcessor* GrBicubicEffect::TestCreate(SkRandom* random,
181                                                 GrContext* context,
182                                                 const GrDrawTargetCaps&,
183                                                 GrTexture* textures[]) {
184    int texIdx = random->nextBool() ? GrProcessorUnitTest::kSkiaPMTextureIdx :
185                                      GrProcessorUnitTest::kAlphaTextureIdx;
186    SkScalar coefficients[16];
187    for (int i = 0; i < 16; i++) {
188        coefficients[i] = random->nextSScalar1();
189    }
190    return GrBicubicEffect::Create(textures[texIdx], coefficients);
191}
192
193//////////////////////////////////////////////////////////////////////////////
194
195bool GrBicubicEffect::ShouldUseBicubic(const SkMatrix& matrix,
196                                       GrTextureParams::FilterMode* filterMode) {
197    if (matrix.isIdentity()) {
198        *filterMode = GrTextureParams::kNone_FilterMode;
199        return false;
200    }
201
202    SkScalar scales[2];
203    if (!matrix.getMinMaxScales(scales) || scales[0] < SK_Scalar1) {
204        // Bicubic doesn't handle arbitrary minimization well, as src texels can be skipped
205        // entirely,
206        *filterMode = GrTextureParams::kMipMap_FilterMode;
207        return false;
208    }
209    // At this point if scales[1] == SK_Scalar1 then the matrix doesn't do any scaling.
210    if (scales[1] == SK_Scalar1) {
211        if (matrix.rectStaysRect() && SkScalarIsInt(matrix.getTranslateX()) &&
212            SkScalarIsInt(matrix.getTranslateY())) {
213            *filterMode = GrTextureParams::kNone_FilterMode;
214        } else {
215            // Use bilerp to handle rotation or fractional translation.
216            *filterMode = GrTextureParams::kBilerp_FilterMode;
217        }
218        return false;
219    }
220    // When we use the bicubic filtering effect each sample is read from the texture using
221    // nearest neighbor sampling.
222    *filterMode = GrTextureParams::kNone_FilterMode;
223    return true;
224}
225