Pull Gpu shader out of SkTwoPointConicalGradient into own file

src/effects/gradients/SkTwoPointConicalGradient_gpu.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#if SK_SUPPORT_GPU
+#include "SkTwoPointConicalGradient_gpu.h"
+#include "GrTBackendEffectFactory.h"
+
+#include "SkTwoPointConicalGradient.h"
+
+// For brevity
+typedef GrGLUniformManager::UniformHandle UniformHandle;
+
+class GrGL2PtConicalGradientEffect : public GrGLGradientEffect {
+public:
+
+    GrGL2PtConicalGradientEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&);
+    virtual ~GrGL2PtConicalGradientEffect() { }
+
+    virtual void emitCode(GrGLShaderBuilder*,
+                          const GrDrawEffect&,
+                          EffectKey,
+                          const char* outputColor,
+                          const char* inputColor,
+                          const TransformedCoordsArray&,
+                          const TextureSamplerArray&) SK_OVERRIDE;
+    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
+
+    static EffectKey GenKey(const GrDrawEffect&, const GrGLCaps& caps);
+
+protected:
+
+    UniformHandle fParamUni;
+
+    const char* fVSVaryingName;
+    const char* fFSVaryingName;
+
+    bool fIsDegenerate;
+
+    // @{
+    /// Values last uploaded as uniforms
+
+    SkScalar fCachedCenter;
+    SkScalar fCachedRadius;
+    SkScalar fCachedDiffRadius;
+
+    // @}
+
+private:
+    
+    typedef GrGLGradientEffect INHERITED;
+
+};
+
+const GrBackendEffectFactory& Gr2PtConicalGradientEffect::getFactory() const {
+    return GrTBackendEffectFactory<Gr2PtConicalGradientEffect>::getInstance();
+}
+    
+Gr2PtConicalGradientEffect::Gr2PtConicalGradientEffect(GrContext* ctx,
+                                                         const SkTwoPointConicalGradient& shader,
+                                                         const SkMatrix& matrix,
+                                                         SkShader::TileMode tm) :
+    INHERITED(ctx, shader, matrix, tm),
+    fCenterX1(shader.getCenterX1()),
+    fRadius0(shader.getStartRadius()),
+    fDiffRadius(shader.getDiffRadius()) {
+    // We pass the linear part of the quadratic as a varying.
+    //    float b = -2.0 * (fCenterX1 * x + fRadius0 * fDiffRadius * z)
+    fBTransform = this->getCoordTransform();
+    SkMatrix& bMatrix = *fBTransform.accessMatrix();
+    SkScalar r0dr = SkScalarMul(fRadius0, fDiffRadius);
+    bMatrix[SkMatrix::kMScaleX] = -2 * (SkScalarMul(fCenterX1, bMatrix[SkMatrix::kMScaleX]) +
+                                        SkScalarMul(r0dr, bMatrix[SkMatrix::kMPersp0]));
+    bMatrix[SkMatrix::kMSkewX] = -2 * (SkScalarMul(fCenterX1, bMatrix[SkMatrix::kMSkewX]) +
+                                       SkScalarMul(r0dr, bMatrix[SkMatrix::kMPersp1]));
+    bMatrix[SkMatrix::kMTransX] = -2 * (SkScalarMul(fCenterX1, bMatrix[SkMatrix::kMTransX]) +
+                                        SkScalarMul(r0dr, bMatrix[SkMatrix::kMPersp2]));
+    this->addCoordTransform(&fBTransform);
+}
+
+GR_DEFINE_EFFECT_TEST(Gr2PtConicalGradientEffect);
+
+GrEffectRef* Gr2PtConicalGradientEffect::TestCreate(SkRandom* random,
+                                            GrContext* context,
+                                            const GrDrawTargetCaps&,
+                                            GrTexture**) {
+    SkPoint center1 = {random->nextUScalar1(), random->nextUScalar1()};
+    SkScalar radius1 = random->nextUScalar1();
+    SkPoint center2;
+    SkScalar radius2;
+    do {
+        center2.set(random->nextUScalar1(), random->nextUScalar1());
+        radius2 = random->nextUScalar1 ();
+        // If the circles are identical the factory will give us an empty shader.
+    } while (radius1 == radius2 && center1 == center2);
+
+    SkColor colors[kMaxRandomGradientColors];
+    SkScalar stopsArray[kMaxRandomGradientColors];
+    SkScalar* stops = stopsArray;
+    SkShader::TileMode tm;
+    int colorCount = RandomGradientParams(random, colors, &stops, &tm);
+    SkAutoTUnref<SkShader> shader(SkGradientShader::CreateTwoPointConical(center1, radius1,
+                                                                          center2, radius2,
+                                                                          colors, stops, colorCount,
+                                                                          tm));
+    SkPaint paint;
+    return shader->asNewEffect(context, paint);
+}
+
+
+/////////////////////////////////////////////////////////////////////
+
+GrGL2PtConicalGradientEffect::GrGL2PtConicalGradientEffect(const GrBackendEffectFactory& factory,
+                                           const GrDrawEffect& drawEffect)
+    : INHERITED(factory)
+    , fVSVaryingName(NULL)
+    , fFSVaryingName(NULL)
+    , fCachedCenter(SK_ScalarMax)
+    , fCachedRadius(-SK_ScalarMax)
+    , fCachedDiffRadius(-SK_ScalarMax) {
+
+    const Gr2PtConicalGradientEffect& data = drawEffect.castEffect<Gr2PtConicalGradientEffect>();
+    fIsDegenerate = data.isDegenerate();
+}
+
+void GrGL2PtConicalGradientEffect::emitCode(GrGLShaderBuilder* builder,
+                                    const GrDrawEffect&,
+                                    EffectKey key,
+                                    const char* outputColor,
+                                    const char* inputColor,
+                                    const TransformedCoordsArray& coords,
+                                    const TextureSamplerArray& samplers) {
+    this->emitUniforms(builder, key);
+    fParamUni = builder->addUniformArray(GrGLShaderBuilder::kFragment_Visibility,
+                                         kFloat_GrSLType, "Conical2FSParams", 6);
+
+    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(fParamUni).appendArrayAccess(0, &p0);
+    builder->getUniformVariable(fParamUni).appendArrayAccess(1, &p1);
+    builder->getUniformVariable(fParamUni).appendArrayAccess(2, &p2);
+    builder->getUniformVariable(fParamUni).appendArrayAccess(3, &p3);
+    builder->getUniformVariable(fParamUni).appendArrayAccess(4, &p4);
+    builder->getUniformVariable(fParamUni).appendArrayAccess(5, &p5);
+
+    // We interpolate the linear component in coords[1].
+    SkASSERT(coords[0].type() == coords[1].type());
+    const char* coords2D;
+    SkString bVar;
+    if (kVec3f_GrSLType == coords[0].type()) {
+        builder->fsCodeAppendf("\tvec3 interpolants = vec3(%s.xy, %s.x) / %s.z;\n",
+                               coords[0].c_str(), coords[1].c_str(), coords[0].c_str());
+        coords2D = "interpolants.xy";
+        bVar = "interpolants.z";
+    } else {
+        coords2D = coords[0].c_str();
+        bVar.printf("%s.x", coords[1].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)
+    builder->fsCodeAppendf("\t%s = vec4(0.0,0.0,0.0,0.0);\n", outputColor);
+
+    // c = (x^2)+(y^2) - params[4]
+    builder->fsCodeAppendf("\tfloat %s = dot(%s, %s) - %s;\n",
+                           cName.c_str(), coords2D, coords2D, p4.c_str());
+
+    // Non-degenerate case (quadratic)
+    if (!fIsDegenerate) {
+
+        // ac4 = params[0] * c
+        builder->fsCodeAppendf("\tfloat %s = %s * %s;\n", ac4Name.c_str(), p0.c_str(),
+                               cName.c_str());
+
+        // d = b^2 - ac4
+        builder->fsCodeAppendf("\tfloat %s = %s * %s - %s;\n", dName.c_str(),
+                               bVar.c_str(), bVar.c_str(), ac4Name.c_str());
+
+        // only proceed if discriminant is >= 0
+        builder->fsCodeAppendf("\tif (%s >= 0.0) {\n", dName.c_str());
+
+        // intermediate value we'll use to compute the roots
+        // q = -0.5 * (b +/- sqrt(d))
+        builder->fsCodeAppendf("\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]
+        builder->fsCodeAppendf("\t\tfloat %s = %s * %s;\n", r0Name.c_str(),
+                               qName.c_str(), p1.c_str());
+        // r1 = c / q
+        builder->fsCodeAppendf("\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:
+        builder->fsCodeAppendf("\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
+        builder->fsCodeAppendf("\t\tif (%s * %s + %s > 0.0) {\n", tName.c_str(),
+                               p5.c_str(), p3.c_str());
+
+        builder->fsCodeAppend("\t\t");
+        this->emitColor(builder, tName.c_str(), key, outputColor, inputColor, samplers);
+
+        // otherwise, if r(t) for the larger root was <= 0, try the other root
+        builder->fsCodeAppend("\t\t} else {\n");
+        builder->fsCodeAppendf("\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
+        builder->fsCodeAppendf("\t\t\tif (%s * %s + %s > 0.0) {\n",
+                               tName.c_str(), p5.c_str(), p3.c_str());
+
+        builder->fsCodeAppend("\t\t\t");
+        this->emitColor(builder, tName.c_str(), key, outputColor, inputColor, samplers);
+
+        // end if (r(t) > 0) for smaller root
+        builder->fsCodeAppend("\t\t\t}\n");
+        // end if (r(t) > 0), else, for larger root
+        builder->fsCodeAppend("\t\t}\n");
+        // end if (discriminant >= 0)
+        builder->fsCodeAppend("\t}\n");
+    } else {
+
+        // linear case: t = -c/b
+        builder->fsCodeAppendf("\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
+        builder->fsCodeAppendf("\tif (%s * %s + %s > 0.0) {\n", tName.c_str(),
+                               p5.c_str(), p3.c_str());
+        builder->fsCodeAppend("\t");
+        this->emitColor(builder, tName.c_str(), key, outputColor, inputColor, samplers);
+        builder->fsCodeAppend("\t}\n");
+    }
+}
+
+void GrGL2PtConicalGradientEffect::setData(const GrGLUniformManager& uman,
+                                   const GrDrawEffect& drawEffect) {
+    INHERITED::setData(uman, drawEffect);
+    const Gr2PtConicalGradientEffect& data = drawEffect.castEffect<Gr2PtConicalGradientEffect>();
+    SkASSERT(data.isDegenerate() == fIsDegenerate);
+    SkScalar centerX1 = data.center();
+    SkScalar radius0 = data.radius();
+    SkScalar diffRadius = data.diffRadius();
+
+    if (fCachedCenter != centerX1 ||
+        fCachedRadius != radius0 ||
+        fCachedDiffRadius != diffRadius) {
+
+        SkScalar a = SkScalarMul(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] = {
+            SkScalarToFloat(a * 4),
+            1.f / (SkScalarToFloat(a)),
+            SkScalarToFloat(centerX1),
+            SkScalarToFloat(radius0),
+            SkScalarToFloat(SkScalarMul(radius0, radius0)),
+            SkScalarToFloat(diffRadius)
+        };
+
+        uman.set1fv(fParamUni, 6, values);
+        fCachedCenter = centerX1;
+        fCachedRadius = radius0;
+        fCachedDiffRadius = diffRadius;
+    }
+}
+
+GrGLEffect::EffectKey GrGL2PtConicalGradientEffect::GenKey(const GrDrawEffect& drawEffect,
+                                                   const GrGLCaps&) {
+    enum {
+        kIsDegenerate = 1 << kBaseKeyBitCnt,
+    };
+
+    EffectKey key = GenBaseGradientKey(drawEffect);
+    if (drawEffect.castEffect<Gr2PtConicalGradientEffect>().isDegenerate()) {
+        key |= kIsDegenerate;
+    }
+    return key;
+}
+#endif
+