Move GPU gradients into src/effects/gradients.
Review URL: https://codereview.appspot.com/6453055

git-svn-id: http://skia.googlecode.com/svn/trunk@4805 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/gradients/SkTwoPointConicalGradient.cpp b/src/effects/gradients/SkTwoPointConicalGradient.cpp
index 91dc768..40ce528 100644
--- a/src/effects/gradients/SkTwoPointConicalGradient.cpp
+++ b/src/effects/gradients/SkTwoPointConicalGradient.cpp
@@ -331,3 +331,320 @@
     buffer.writeScalar(fRadius2);
 }
 
+/////////////////////////////////////////////////////////////////////
+
+// For brevity
+typedef GrGLUniformManager::UniformHandle UniformHandle;
+static const UniformHandle kInvalidUniformHandle = GrGLUniformManager::kInvalidUniformHandle;
+
+class GrGLConical2Gradient : public GrGLGradientStage {
+
+public:
+
+    GrGLConical2Gradient(const GrProgramStageFactory& factory,
+                         const GrCustomStage&);
+    virtual ~GrGLConical2Gradient() { }
+
+    virtual void setupVariables(GrGLShaderBuilder* builder) SK_OVERRIDE;
+    virtual void emitVS(GrGLShaderBuilder* builder,
+                        const char* vertexCoords) SK_OVERRIDE;
+    virtual void emitFS(GrGLShaderBuilder* builder,
+                        const char* outputColor,
+                        const char* inputColor,
+                        const char* samplerName) SK_OVERRIDE;
+    virtual void setData(const GrGLUniformManager&,
+                         const GrCustomStage&,
+                         const GrRenderTarget*,
+                         int stageNum) SK_OVERRIDE;
+
+    static StageKey GenKey(const GrCustomStage& s) {
+        return (static_cast<const GrConical2Gradient&>(s).isDegenerate());
+    }
+
+protected:
+
+    UniformHandle           fVSParamUni;
+    UniformHandle           fFSParamUni;
+
+    const char* fVSVaryingName;
+    const char* fFSVaryingName;
+
+    bool fIsDegenerate;
+
+    // @{
+    /// Values last uploaded as uniforms
+
+    GrScalar fCachedCenter;
+    GrScalar fCachedRadius;
+    GrScalar fCachedDiffRadius;
+
+    // @}
+
+private:
+
+    typedef GrGLGradientStage INHERITED;
+
+};
+
+GrGLConical2Gradient::GrGLConical2Gradient(
+        const GrProgramStageFactory& factory,
+        const GrCustomStage& baseData)
+    : INHERITED(factory)
+    , fVSParamUni(kInvalidUniformHandle)
+    , fFSParamUni(kInvalidUniformHandle)
+    , fVSVaryingName(NULL)
+    , fFSVaryingName(NULL)
+    , fCachedCenter(GR_ScalarMax)
+    , fCachedRadius(-GR_ScalarMax)
+    , fCachedDiffRadius(-GR_ScalarMax) {
+
+    const GrConical2Gradient& data =
+        static_cast<const GrConical2Gradient&>(baseData);
+    fIsDegenerate = data.isDegenerate();
+}
+
+void GrGLConical2Gradient::setupVariables(GrGLShaderBuilder* builder) {
+    // 2 copies of uniform array, 1 for each of vertex & fragment shader,
+    // to work around Xoom bug. Doesn't seem to cause performance decrease
+    // in test apps, but need to keep an eye on it.
+    fVSParamUni = builder->addUniformArray(GrGLShaderBuilder::kVertex_ShaderType,
+                                           kFloat_GrSLType, "Conical2VSParams", 6);
+    fFSParamUni = builder->addUniformArray(GrGLShaderBuilder::kFragment_ShaderType,
+                                           kFloat_GrSLType, "Conical2FSParams", 6);
+
+    // For radial gradients without perspective we can pass the linear
+    // part of the quadratic as a varying.
+    if (builder->fVaryingDims == builder->fCoordDims) {
+        builder->addVarying(kFloat_GrSLType, "Conical2BCoeff",
+                            &fVSVaryingName, &fFSVaryingName);
+    }
+}
+
+void GrGLConical2Gradient::emitVS(GrGLShaderBuilder* builder,
+                                  const char* vertexCoords) {
+    SkString* code = &builder->fVSCode;
+    SkString p2; // distance between centers
+    SkString p3; // start radius
+    SkString p5; // difference in radii (r1 - r0)
+    builder->getUniformVariable(fVSParamUni).appendArrayAccess(2, &p2);
+    builder->getUniformVariable(fVSParamUni).appendArrayAccess(3, &p3);
+    builder->getUniformVariable(fVSParamUni).appendArrayAccess(5, &p5);
+
+    // For radial gradients without perspective we can pass the linear
+    // part of the quadratic as a varying.
+    if (builder->fVaryingDims == builder->fCoordDims) {
+        // r2Var = -2 * (r2Parm[2] * varCoord.x - r2Param[3] * r2Param[5])
+        code->appendf("\t%s = -2.0 * (%s * %s.x + %s * %s);\n",
+                      fVSVaryingName, p2.c_str(),
+                      vertexCoords, p3.c_str(), p5.c_str());
+    }
+}
+
+void GrGLConical2Gradient::emitFS(GrGLShaderBuilder* builder,
+                                  const char* outputColor,
+                                  const char* inputColor,
+                                  const char* samplerName) {
+    SkString* code = &builder->fFSCode;
+
+    SkString cName("c");
+    SkString ac4Name("ac4");
+    SkString dName("d");
+    SkString qName("q");
+    SkString r0Name("r0");
+    SkString r1Name("r1");
+    SkString tName("t");
+    SkString p0; // 4a
+    SkString p1; // 1/a
+    SkString p2; // distance between centers
+    SkString p3; // start radius
+    SkString p4; // start radius squared
+    SkString p5; // difference in radii (r1 - r0)
+
+    builder->getUniformVariable(fFSParamUni).appendArrayAccess(0, &p0);
+    builder->getUniformVariable(fFSParamUni).appendArrayAccess(1, &p1);
+    builder->getUniformVariable(fFSParamUni).appendArrayAccess(2, &p2);
+    builder->getUniformVariable(fFSParamUni).appendArrayAccess(3, &p3);
+    builder->getUniformVariable(fFSParamUni).appendArrayAccess(4, &p4);
+    builder->getUniformVariable(fFSParamUni).appendArrayAccess(5, &p5);
+
+    // If we we're able to interpolate the linear component,
+    // bVar is the varying; otherwise compute it
+    SkString bVar;
+    if (builder->fCoordDims == builder->fVaryingDims) {
+        bVar = fFSVaryingName;
+        GrAssert(2 == builder->fVaryingDims);
+    } else {
+        GrAssert(3 == builder->fVaryingDims);
+        bVar = "b";
+        code->appendf("\tfloat %s = -2.0 * (%s * %s.x + %s * %s);\n", 
+                      bVar.c_str(), p2.c_str(), builder->fSampleCoords.c_str(), 
+                      p3.c_str(), p5.c_str());
+    }
+
+    // output will default to transparent black (we simply won't write anything
+    // else to it if invalid, instead of discarding or returning prematurely)
+    code->appendf("\t%s = vec4(0.0,0.0,0.0,0.0);\n", outputColor);
+
+    // c = (x^2)+(y^2) - params[4]
+    code->appendf("\tfloat %s = dot(%s, %s) - %s;\n", cName.c_str(), 
+                  builder->fSampleCoords.c_str(), builder->fSampleCoords.c_str(),
+                  p4.c_str());
+
+    // Non-degenerate case (quadratic)
+    if (!fIsDegenerate) {
+
+        // ac4 = params[0] * c
+        code->appendf("\tfloat %s = %s * %s;\n", ac4Name.c_str(), p0.c_str(),
+                      cName.c_str());
+        
+        // d = b^2 - ac4
+        code->appendf("\tfloat %s = %s * %s - %s;\n", dName.c_str(), 
+                      bVar.c_str(), bVar.c_str(), ac4Name.c_str());
+
+        // only proceed if discriminant is >= 0
+        code->appendf("\tif (%s >= 0.0) {\n", dName.c_str());
+
+        // intermediate value we'll use to compute the roots
+        // q = -0.5 * (b +/- sqrt(d))
+        code->appendf("\t\tfloat %s = -0.5 * (%s + (%s < 0.0 ? -1.0 : 1.0)"
+                      " * sqrt(%s));\n", qName.c_str(), bVar.c_str(), 
+                      bVar.c_str(), dName.c_str());
+
+        // compute both roots
+        // r0 = q * params[1]
+        code->appendf("\t\tfloat %s = %s * %s;\n", r0Name.c_str(), 
+                      qName.c_str(), p1.c_str());
+        // r1 = c / q
+        code->appendf("\t\tfloat %s = %s / %s;\n", r1Name.c_str(), 
+                      cName.c_str(), qName.c_str());
+
+        // Note: If there are two roots that both generate radius(t) > 0, the 
+        // Canvas spec says to choose the larger t.
+
+        // so we'll look at the larger one first:
+        code->appendf("\t\tfloat %s = max(%s, %s);\n", tName.c_str(), 
+                      r0Name.c_str(), r1Name.c_str());
+
+        // if r(t) > 0, then we're done; t will be our x coordinate
+        code->appendf("\t\tif (%s * %s + %s > 0.0) {\n", tName.c_str(), 
+                      p5.c_str(), p3.c_str());
+
+        code->appendf("\t\t");
+        this->emitColorLookup(builder, tName.c_str(), outputColor, samplerName);
+
+        // otherwise, if r(t) for the larger root was <= 0, try the other root
+        code->appendf("\t\t} else {\n");
+        code->appendf("\t\t\t%s = min(%s, %s);\n", tName.c_str(), 
+                      r0Name.c_str(), r1Name.c_str());
+
+        // if r(t) > 0 for the smaller root, then t will be our x coordinate
+        code->appendf("\t\t\tif (%s * %s + %s > 0.0) {\n",
+                      tName.c_str(), p5.c_str(), p3.c_str());
+
+        code->appendf("\t\t\t");
+        this->emitColorLookup(builder, tName.c_str(), outputColor, samplerName);
+
+        // end if (r(t) > 0) for smaller root 
+        code->appendf("\t\t\t}\n");
+        // end if (r(t) > 0), else, for larger root
+        code->appendf("\t\t}\n");
+        // end if (discriminant >= 0)
+        code->appendf("\t}\n");
+    } else {
+
+        // linear case: t = -c/b
+        code->appendf("\tfloat %s = -(%s / %s);\n", tName.c_str(), 
+                      cName.c_str(), bVar.c_str());
+
+        // if r(t) > 0, then t will be the x coordinate
+        code->appendf("\tif (%s * %s + %s > 0.0) {\n", tName.c_str(),
+                      p5.c_str(), p3.c_str());
+        code->appendf("\t");
+        this->emitColorLookup(builder, tName.c_str(), outputColor, samplerName);
+        code->appendf("\t}\n");
+    }
+}
+
+void GrGLConical2Gradient::setData(const GrGLUniformManager& uman,
+                                   const GrCustomStage& baseData,
+                                   const GrRenderTarget*,
+                                   int stageNum) {
+    const GrConical2Gradient& data =
+        static_cast<const GrConical2Gradient&>(baseData);
+    GrAssert(data.isDegenerate() == fIsDegenerate);
+    GrScalar centerX1 = data.center();
+    GrScalar radius0 = data.radius();
+    GrScalar diffRadius = data.diffRadius();
+
+    if (fCachedCenter != centerX1 ||
+        fCachedRadius != radius0 ||
+        fCachedDiffRadius != diffRadius) {
+
+        GrScalar a = GrMul(centerX1, centerX1) - diffRadius * diffRadius;
+
+        // When we're in the degenerate (linear) case, the second
+        // value will be INF but the program doesn't read it. (We
+        // use the same 6 uniforms even though we don't need them
+        // all in the linear case just to keep the code complexity
+        // down).
+        float values[6] = {
+            GrScalarToFloat(a * 4),
+            1.f / (GrScalarToFloat(a)),
+            GrScalarToFloat(centerX1),
+            GrScalarToFloat(radius0),
+            GrScalarToFloat(SkScalarMul(radius0, radius0)),
+            GrScalarToFloat(diffRadius)
+        };
+
+        uman.set1fv(fVSParamUni, 0, 6, values);
+        uman.set1fv(fFSParamUni, 0, 6, values);
+        fCachedCenter = centerX1;
+        fCachedRadius = radius0;
+        fCachedDiffRadius = diffRadius;
+    }
+}
+
+
+/////////////////////////////////////////////////////////////////////
+
+GrConical2Gradient::GrConical2Gradient(GrTexture* texture,
+                                       GrScalar center,
+                                       GrScalar radius,
+                                       GrScalar diffRadius)
+    : INHERITED (texture)
+    , fCenterX1 (center)
+    , fRadius0 (radius)
+    , fDiffRadius (diffRadius) {
+
+}
+
+GrConical2Gradient::GrConical2Gradient(GrContext* ctx, 
+                                       const SkShader& shader,
+                                       GrSamplerState* sampler,
+                                       SkScalar center,
+                                       SkScalar startRadius,
+                                       SkScalar diffRadius)
+                                       : INHERITED(ctx, shader, sampler) 
+                                       , fCenterX1(center)
+                                       , fRadius0(startRadius)
+                                       , fDiffRadius(diffRadius) {
+}
+
+GrConical2Gradient::~GrConical2Gradient() {
+
+}
+
+
+const GrProgramStageFactory& GrConical2Gradient::getFactory() const {
+    return GrTProgramStageFactory<GrConical2Gradient>::getInstance();
+}
+
+bool GrConical2Gradient::isEqual(const GrCustomStage& sBase) const {
+    const GrConical2Gradient& s = static_cast<const GrConical2Gradient&>(sBase);
+    return (INHERITED::isEqual(sBase) &&
+            this->fCenterX1 == s.fCenterX1 &&
+            this->fRadius0 == s.fRadius0 &&
+            this->fDiffRadius == s.fDiffRadius);
+}
+
+