C++ GrGLFragmentBuilder::emitFunction方法代码示例

void GrGLBicubicEffect::emitCode(EmitArgs& args) {
    const GrTextureDomain& domain = args.fFp.cast<GrBicubicEffect>().domain();

    fCoefficientsUni = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                           kMat44f_GrSLType, kDefault_GrSLPrecision,
                                           "Coefficients");
    fImageIncrementUni = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                             kVec2f_GrSLType, kDefault_GrSLPrecision,
                                             "ImageIncrement");

    const char* imgInc = args.fBuilder->getUniformCStr(fImageIncrementUni);
    const char* coeff = args.fBuilder->getUniformCStr(fCoefficientsUni);

    SkString cubicBlendName;

    static const GrGLShaderVar gCubicBlendArgs[] = {
        GrGLShaderVar("coefficients",  kMat44f_GrSLType),
        GrGLShaderVar("t",             kFloat_GrSLType),
        GrGLShaderVar("c0",            kVec4f_GrSLType),
        GrGLShaderVar("c1",            kVec4f_GrSLType),
        GrGLShaderVar("c2",            kVec4f_GrSLType),
        GrGLShaderVar("c3",            kVec4f_GrSLType),
    };
    GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder();
    SkString coords2D = fsBuilder->ensureFSCoords2D(args.fCoords, 0);
    fsBuilder->emitFunction(kVec4f_GrSLType,
                            "cubicBlend",
                            SK_ARRAY_COUNT(gCubicBlendArgs),
                            gCubicBlendArgs,
                            "\tvec4 ts = vec4(1.0, t, t * t, t * t * t);\n"
                            "\tvec4 c = coefficients * ts;\n"
                            "\treturn c.x * c0 + c.y * c1 + c.z * c2 + c.w * c3;\n",
                            &cubicBlendName);
    fsBuilder->codeAppendf("\tvec2 coord = %s - %s * vec2(0.5);\n", coords2D.c_str(), imgInc);
    // We unnormalize the coord in order to determine our fractional offset (f) within the texel
    // We then snap coord to a texel center and renormalize. The snap prevents cases where the
    // starting coords are near a texel boundary and accumulations of imgInc would cause us to skip/
    // double hit a texel.
    fsBuilder->codeAppendf("\tcoord /= %s;\n", imgInc);
    fsBuilder->codeAppend("\tvec2 f = fract(coord);\n");
    fsBuilder->codeAppendf("\tcoord = (coord - f + vec2(0.5)) * %s;\n", imgInc);
    fsBuilder->codeAppend("\tvec4 rowColors[4];\n");
    for (int y = 0; y < 4; ++y) {
        for (int x = 0; x < 4; ++x) {
            SkString coord;
            coord.printf("coord + %s * vec2(%d, %d)", imgInc, x - 1, y - 1);
            SkString sampleVar;
            sampleVar.printf("rowColors[%d]", x);
            fDomain.sampleTexture(fsBuilder, domain, sampleVar.c_str(), coord, args.fSamplers[0]);
        }
        fsBuilder->codeAppendf("\tvec4 s%d = %s(%s, f.x, rowColors[0], rowColors[1], rowColors[2], rowColors[3]);\n", y, cubicBlendName.c_str(), coeff);
    }
    SkString bicubicColor;
    bicubicColor.printf("%s(%s, f.y, s0, s1, s2, s3)", cubicBlendName.c_str(), coeff);
    fsBuilder->codeAppendf("\t%s = %s;\n", args.fOutputColor,(GrGLSLExpr4(bicubicColor.c_str()) *
                           GrGLSLExpr4(args.fInputColor)).c_str());
}

//.........这里部分代码省略.........
    noiseCode.appendf("\n\t%s.x = mix(%s.x, %s.y, %s.x);", ab, uv, uv, noiseSmooth);

    noiseCode.appendf("\n\t%s.y -= 1.0;", fractVal);
    // Compute v, at offset (-1,-1)
    {
        SkString latticeCoords("");
        latticeCoords.appendf("vec2(%s.w, %s)", bcoords, chanCoord);
        noiseCode.append("\n\tlattice = ");
        fsBuilder->appendTextureLookup(&noiseCode, samplers[1], latticeCoords.c_str(),
            kVec2f_GrSLType);
        noiseCode.appendf(".bgra;\n\t%s.y = ", uv);
        noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
    }

    noiseCode.appendf("\n\t%s.x += 1.0;", fractVal);
    // Compute u, at offset (0,-1)
    {
        SkString latticeCoords("");
        latticeCoords.appendf("vec2(%s.z, %s)", bcoords, chanCoord);
        noiseCode.append("\n\tlattice = ");
        fsBuilder->appendTextureLookup(&noiseCode, samplers[1], latticeCoords.c_str(),
            kVec2f_GrSLType);
        noiseCode.appendf(".bgra;\n\t%s.x = ", uv);
        noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
    }

    // Compute 'b' as a linear interpolation of 'u' and 'v'
    noiseCode.appendf("\n\t%s.y = mix(%s.x, %s.y, %s.x);", ab, uv, uv, noiseSmooth);
    // Compute the noise as a linear interpolation of 'a' and 'b'
    noiseCode.appendf("\n\treturn mix(%s.x, %s.y, %s.y);\n", ab, ab, noiseSmooth);

    SkString noiseFuncName;
    if (fStitchTiles) {
        fsBuilder->emitFunction(kFloat_GrSLType,
                                "perlinnoise", SK_ARRAY_COUNT(gPerlinNoiseStitchArgs),
                                gPerlinNoiseStitchArgs, noiseCode.c_str(), &noiseFuncName);
    } else {
        fsBuilder->emitFunction(kFloat_GrSLType,
                                "perlinnoise", SK_ARRAY_COUNT(gPerlinNoiseArgs),
                                gPerlinNoiseArgs, noiseCode.c_str(), &noiseFuncName);
    }

    // There are rounding errors if the floor operation is not performed here
    fsBuilder->codeAppendf("\n\t\tvec2 %s = floor(%s.xy) * %s;",
                           noiseVec, vCoords.c_str(), baseFrequencyUni);

    // Clear the color accumulator
    fsBuilder->codeAppendf("\n\t\t%s = vec4(0.0);", outputColor);

    if (fStitchTiles) {
        // Set up TurbulenceInitial stitch values.
        fsBuilder->codeAppendf("\n\t\tvec2 %s = %s;", stitchData, stitchDataUni);
    }

    fsBuilder->codeAppendf("\n\t\tfloat %s = 1.0;", ratio);

    // Loop over all octaves
    fsBuilder->codeAppendf("\n\t\tfor (int octave = 0; octave < %d; ++octave) {", fNumOctaves);

    fsBuilder->codeAppendf("\n\t\t\t%s += ", outputColor);
    if (fType != SkPerlinNoiseShader::kFractalNoise_Type) {
        fsBuilder->codeAppend("abs(");
    }
    if (fStitchTiles) {
        fsBuilder->codeAppendf(
            "vec4(\n\t\t\t\t%s(%s, %s, %s),\n\t\t\t\t%s(%s, %s, %s),"