Add GrGradientEffects files. These implementations will be invoked from

GrGLPrograms in a further change, replacing the current CoordMapping
enums.

http://codereview.appspot.com/6250081/



git-svn-id: http://skia.googlecode.com/svn/trunk@4104 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 458 insertions, 0 deletions

diff --git a/src/gpu/effects/GrGradientEffects.cpp b/src/gpu/effects/GrGradientEffects.cpp
new file mode 100644
index 0000000000..3f498b332d
--- /dev/null
+++ b/src/gpu/effects/GrGradientEffects.cpp
@@ -0,0 +1,365 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrGradientEffects.h"
+#include "gl/GrGLProgramStage.h"
+#include "GrProgramStageFactory.h"
+
+/////////////////////////////////////////////////////////////////////
+
+class GrGLRadialGradient : public GrGLProgramStage {
+
+public:
+
+    GrGLRadialGradient(const GrProgramStageFactory& factory,
+                       const GrCustomStage&) : INHERITED (factory) { }
+    virtual ~GrGLRadialGradient() { }
+
+    virtual void emitVS(GrGLShaderBuilder* state,
+                        const char* vertexCoords) SK_OVERRIDE { }
+    virtual void emitFS(GrGLShaderBuilder* state,
+                        const char* outputColor,
+                        const char* inputColor,
+                        const char* samplerName) SK_OVERRIDE;
+
+    static StageKey GenKey(const GrCustomStage& s) { return 0; }
+
+private:
+
+    typedef GrGLProgramStage INHERITED;
+
+};
+
+void GrGLRadialGradient::emitFS(GrGLShaderBuilder* state,
+                        const char* outputColor,
+                        const char* inputColor,
+                        const char* samplerName) {
+    state->fSampleCoords.printf("vec2(length(%s.xy), 0.5)",
+                                state->fSampleCoords.c_str());
+    state->fComplexCoord = true;
+
+    state->emitDefaultFetch(outputColor, samplerName);
+}
+
+
+/////////////////////////////////////////////////////////////////////
+
+
+GrRadialGradient::GrRadialGradient() {
+
+}
+
+GrRadialGradient::~GrRadialGradient() {
+
+}
+
+
+const GrProgramStageFactory& GrRadialGradient::getFactory() const {
+    return GrTProgramStageFactory<GrRadialGradient>::getInstance();
+}
+
+bool GrRadialGradient::isEqual(const GrCustomStage& sBase) const {
+    return true;
+}
+
+/////////////////////////////////////////////////////////////////////
+
+class GrGLRadial2Gradient : public GrGLProgramStage {
+
+public:
+
+    GrGLRadial2Gradient(const GrProgramStageFactory& factory,
+                        const GrCustomStage&);
+    virtual ~GrGLRadial2Gradient() { }
+
+    virtual void setupVariables(GrGLShaderBuilder* state,
+                                int stage) SK_OVERRIDE;
+    virtual void emitVS(GrGLShaderBuilder* state,
+                        const char* vertexCoords) SK_OVERRIDE;
+    virtual void emitFS(GrGLShaderBuilder* state,
+                        const char* outputColor,
+                        const char* inputColor,
+                        const char* samplerName) SK_OVERRIDE;
+    virtual void initUniforms(const GrGLInterface*, int programID) SK_OVERRIDE;
+    virtual void setData(const GrGLInterface*,
+                         const GrGLTexture&,
+                         GrCustomStage*,
+                         int stageNum) SK_OVERRIDE;
+
+    static StageKey GenKey(const GrCustomStage& s) {
+        return (static_cast<const GrRadial2Gradient&>(s).isDegenerate());
+    }
+
+protected:
+
+    const GrGLShaderVar* fParamVar;
+    GrGLint fParamLocation;
+
+    const char* fVSVaryingName;
+    const char* fFSVaryingName;
+
+    bool fIsDegenerate;
+
+    // @{
+    /// Values last uploaded as uniforms
+
+    GrScalar fCachedCenter;
+    GrScalar fCachedRadius;
+    SkBool8  fCachedPosRoot;
+
+    // @}
+
+private:
+
+    typedef GrGLProgramStage INHERITED;
+
+};
+
+GrGLRadial2Gradient::GrGLRadial2Gradient(
+        const GrProgramStageFactory& factory,
+        const GrCustomStage& baseData)
+    : INHERITED(factory)
+    , fParamVar(NULL)
+    , fVSVaryingName(NULL)
+    , fFSVaryingName(NULL)
+    , fCachedCenter(GR_ScalarMax)
+    , fCachedRadius(-GR_ScalarMax)
+    , fCachedPosRoot(0) {
+
+    const GrRadial2Gradient& data =
+        static_cast<const GrRadial2Gradient&>(baseData);
+    fIsDegenerate = data.isDegenerate();
+}
+
+void GrGLRadial2Gradient::setupVariables(GrGLShaderBuilder* state, int stage) {
+    fParamVar = &state->addUniform(
+        GrGLShaderBuilder::kBoth_VariableLifetime,
+        kFloat_GrSLType, "uRadial2Params", stage, 6);
+
+    fParamLocation = GrGLProgramStage::kUseUniform;
+
+    // For radial gradients without perspective we can pass the linear
+    // part of the quadratic as a varying.
+    if (state->fVaryingDims == state->fCoordDims) {
+        state->addVarying(kFloat_GrSLType, "Radial2BCoeff", stage,
+                          &fVSVaryingName, &fFSVaryingName);
+    }
+}
+
+void GrGLRadial2Gradient::emitVS(GrGLShaderBuilder* state,
+                        const char* vertexCoords) {
+    GrStringBuilder* code = &state->fVSCode;
+    GrStringBuilder p2;
+    GrStringBuilder p3;
+    fParamVar->appendArrayAccess(2, &p2);
+    fParamVar->appendArrayAccess(3, &p3);
+
+    // For radial gradients without perspective we can pass the linear
+    // part of the quadratic as a varying.
+    if (state->fVaryingDims == state->fCoordDims) {
+        // r2Var = 2 * (r2Parm[2] * varCoord.x - r2Param[3])
+        code->appendf("\t%s = 2.0 *(%s * %s.x - %s);\n",
+                      fVSVaryingName, p2.c_str(),
+                      vertexCoords, p3.c_str());
+    }
+}
+
+void GrGLRadial2Gradient::emitFS(GrGLShaderBuilder* state,
+                        const char* outputColor,
+                        const char* inputColor,
+                        const char* samplerName) {
+    GrStringBuilder* code = &state->fFSCode;
+    GrStringBuilder cName("c");
+    GrStringBuilder ac4Name("ac4");
+    GrStringBuilder rootName("root");
+    GrStringBuilder p0;
+    GrStringBuilder p1;
+    GrStringBuilder p2;
+    GrStringBuilder p3;
+    GrStringBuilder p4;
+    GrStringBuilder p5;
+    fParamVar->appendArrayAccess(0, &p0);
+    fParamVar->appendArrayAccess(1, &p1);
+    fParamVar->appendArrayAccess(2, &p2);
+    fParamVar->appendArrayAccess(3, &p3);
+    fParamVar->appendArrayAccess(4, &p4);
+    fParamVar->appendArrayAccess(5, &p5);
+
+    // If we we're able to interpolate the linear component,
+    // bVar is the varying; otherwise compute it
+    GrStringBuilder bVar;
+    if (state->fCoordDims == state->fVaryingDims) {
+        bVar = fFSVaryingName;
+        GrAssert(2 == state->fVaryingDims);
+    } else {
+        GrAssert(3 == state->fVaryingDims);
+        bVar = "b";
+        //bVar.appendS32(stageNum);
+        code->appendf("\tfloat %s = 2.0 * (%s * %s.x - %s);\n",
+                      bVar.c_str(), p2.c_str(),
+                      state->fSampleCoords.c_str(), p3.c_str());
+    }
+
+    // c = (x^2)+(y^2) - params[4]
+    code->appendf("\tfloat %s = dot(%s, %s) - %s;\n",
+                  cName.c_str(), state->fSampleCoords.c_str(),
+                  state->fSampleCoords.c_str(),
+                  p4.c_str());
+
+    // If we aren't degenerate, emit some extra code, and accept a slightly
+    // more complex coord.
+    if (fIsDegenerate) {
+
+        // ac4 = 4.0 * params[0] * c
+        code->appendf("\tfloat %s = %s * 4.0 * %s;\n",
+                      ac4Name.c_str(), p0.c_str(),
+                      cName.c_str());
+
+        // root = sqrt(b^2-4ac)
+        // (abs to avoid exception due to fp precision)
+        code->appendf("\tfloat %s = sqrt(abs(%s*%s - %s));\n",
+                      rootName.c_str(), bVar.c_str(), bVar.c_str(),
+                      ac4Name.c_str());
+
+        // x coord is: (-b + params[5] * sqrt(b^2-4ac)) * params[1]
+        // y coord is 0.5 (texture is effectively 1D)
+        state->fSampleCoords.printf("vec2((-%s + %s * %s) * %s, 0.5)",
+                            bVar.c_str(), p5.c_str(),
+                            rootName.c_str(), p1.c_str());
+    } else {
+        // x coord is: -c/b
+        // y coord is 0.5 (texture is effectively 1D)
+        state->fSampleCoords.printf("vec2((-%s / %s), 0.5)",
+                            cName.c_str(), bVar.c_str());
+    }
+    state->fComplexCoord = true;
+
+    state->emitDefaultFetch(outputColor, samplerName);
+}
+
+void GrGLRadial2Gradient::initUniforms(const GrGLInterface* gl, int programID) {
+    GR_GL_CALL_RET(gl, fParamLocation,
+        GetUniformLocation(programID, fParamVar->getName().c_str()));
+}
+
+void GrGLRadial2Gradient::setData(const GrGLInterface* gl,
+                                 const GrGLTexture& texture,
+                                 GrCustomStage* baseData,
+                                 int stageNum) {
+    const GrRadial2Gradient* data =
+        static_cast<const GrRadial2Gradient*>(baseData);
+    GrAssert(data->isDegenerate() == fIsDegenerate);
+    GrScalar centerX1 = data->center();
+    GrScalar radius0 = data->radius();
+    if (fCachedCenter != centerX1 ||
+        fCachedRadius != radius0 ||
+        fCachedPosRoot != data->isPosRoot()) {
+
+        GrScalar a = GrMul(centerX1, centerX1) - GR_Scalar1;
+
+        // 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),
+            1 / (2.f * GrScalarToFloat(a)),
+            GrScalarToFloat(centerX1),
+            GrScalarToFloat(radius0),
+            GrScalarToFloat(GrMul(radius0, radius0)),
+            data->isPosRoot() ? 1.f : -1.f
+        };
+
+        GR_GL_CALL(gl, Uniform1fv(fParamLocation, 6, values));
+        fCachedCenter = centerX1;
+        fCachedRadius = radius0;
+        fCachedPosRoot = data->isPosRoot();
+    }
+}
+
+
+/////////////////////////////////////////////////////////////////////
+
+GrRadial2Gradient::GrRadial2Gradient(GrScalar center,
+                                     GrScalar radius,
+                                     bool posRoot)
+    : fCenterX1 (center)
+    , fRadius0 (radius)
+    , fPosRoot (posRoot) {
+
+}
+
+GrRadial2Gradient::~GrRadial2Gradient() {
+
+}
+
+
+const GrProgramStageFactory& GrRadial2Gradient::getFactory() const {
+    return GrTProgramStageFactory<GrRadial2Gradient>::getInstance();
+}
+
+bool GrRadial2Gradient::isEqual(const GrCustomStage& sBase) const {
+    const GrRadial2Gradient& s = static_cast<const GrRadial2Gradient&>(sBase);
+    return (this->isDegenerate() == s.isDegenerate());
+}
+
+/////////////////////////////////////////////////////////////////////
+
+class GrGLSweepGradient : public GrGLProgramStage {
+
+public:
+
+    GrGLSweepGradient(const GrProgramStageFactory& factory,
+                      const GrCustomStage&) : INHERITED (factory) { }
+    virtual ~GrGLSweepGradient() { }
+
+    virtual void emitVS(GrGLShaderBuilder* state,
+                        const char* vertexCoords) SK_OVERRIDE { }
+    virtual void emitFS(GrGLShaderBuilder* state,
+                        const char* outputColor,
+                        const char* inputColor,
+                        const char* samplerName) SK_OVERRIDE;
+
+    static StageKey GenKey(const GrCustomStage& s) { return 0; }
+
+private:
+
+    typedef GrGLProgramStage INHERITED;
+
+};
+
+void GrGLSweepGradient::emitFS(GrGLShaderBuilder* state,
+                              const char* outputColor,
+                              const char* inputColor,
+                              const char* samplerName) {
+    state->fSampleCoords.printf(
+        "vec2(atan(- %s.y, - %s.x) * 0.1591549430918 + 0.5, 0.5)",
+        state->fSampleCoords.c_str(), state->fSampleCoords.c_str());
+    state->fComplexCoord = true;
+
+    state->emitDefaultFetch(outputColor, samplerName);
+}
+
+/////////////////////////////////////////////////////////////////////
+
+GrSweepGradient::GrSweepGradient() {
+
+}
+
+GrSweepGradient::~GrSweepGradient() {
+
+}
+
+const GrProgramStageFactory& GrSweepGradient::getFactory() const {
+    return GrTProgramStageFactory<GrSweepGradient>::getInstance();
+}
+
+bool GrSweepGradient::isEqual(const GrCustomStage& sBase) const {
+    return true;
+}
+
diff --git a/src/gpu/effects/GrGradientEffects.h b/src/gpu/effects/GrGradientEffects.h
new file mode 100644
index 0000000000..8d67c25268
--- /dev/null
+++ b/src/gpu/effects/GrGradientEffects.h
@@ -0,0 +1,93 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrGradientEffects_DEFINED
+#define GrGradientEffects_DEFINED
+
+#include "GrCustomStage.h"
+#include "GrTypes.h"
+#include "GrScalar.h"
+
+class GrGLRadialGradient;
+
+class GrRadialGradient : public GrCustomStage {
+
+public:
+
+    GrRadialGradient();
+    virtual ~GrRadialGradient();
+
+    static const char* Name() { return "Radial Gradient"; }
+    virtual const GrProgramStageFactory& getFactory() const SK_OVERRIDE;
+    virtual bool isEqual(const GrCustomStage&) const SK_OVERRIDE;
+
+    typedef GrGLRadialGradient GLProgramStage;
+
+private:
+
+    typedef GrCustomStage INHERITED;
+};
+
+class GrGLRadial2Gradient;
+
+class GrRadial2Gradient : public GrCustomStage {
+
+public:
+
+    GrRadial2Gradient(GrScalar center, GrScalar radius, bool posRoot);
+    virtual ~GrRadial2Gradient();
+
+    static const char* Name() { return "Two-Point Radial Gradient"; }
+    virtual const GrProgramStageFactory& getFactory() const SK_OVERRIDE;
+    virtual bool isEqual(const GrCustomStage&) const SK_OVERRIDE;
+
+    // The radial gradient parameters can collapse to a linear (instead
+    // of quadratic) equation.
+    bool isDegenerate() const { return GR_Scalar1 == fCenterX1; }
+    GrScalar center() const { return fCenterX1; }
+    GrScalar radius() const { return fRadius0; }
+    bool isPosRoot() const { return SkToBool(fPosRoot); }
+
+    typedef GrGLRadial2Gradient GLProgramStage;
+
+private:
+
+    // @{
+    // Cache of values - these can change arbitrarily, EXCEPT
+    // we shouldn't change between degenerate and non-degenerate?!
+
+    GrScalar fCenterX1;
+    GrScalar fRadius0;
+    SkBool8  fPosRoot;
+
+    // @}
+
+    typedef GrCustomStage INHERITED;
+};
+
+class GrGLSweepGradient;
+
+class GrSweepGradient : public GrCustomStage {
+
+public:
+
+    GrSweepGradient();
+    virtual ~GrSweepGradient();
+
+    static const char* Name() { return "Sweep Gradient"; }
+    virtual const GrProgramStageFactory& getFactory() const SK_OVERRIDE;
+    virtual bool isEqual(const GrCustomStage&) const SK_OVERRIDE;
+
+    typedef GrGLSweepGradient GLProgramStage;
+
+protected:
+
+    typedef GrCustomStage INHERITED;
+};
+
+#endif
+