src/gpu/effects/GrConvexPolyEffect.cpp - platform/external/skqp - Gitiles

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "GrConvexPolyEffect.h"

 #include "gl/GrGLEffect.h"
 #include "gl/GrGLSL.h"
 #include "GrTBackendEffectFactory.h"

 #include "SkPath.h"

 //////////////////////////////////////////////////////////////////////////////
 class GLAARectEffect;

 class AARectEffect : public GrEffect {
 public:
     typedef GLAARectEffect GLEffect;
     typedef GrConvexPolyEffect::EdgeType EdgeType;

     const SkRect& getRect() const { return fRect; }

     static const char* Name() { return "AARect"; }

     static GrEffectRef* Create(EdgeType edgeType, const SkRect& rect) {
         return CreateEffectRef(AutoEffectUnref(SkNEW_ARGS(AARectEffect, (edgeType, rect))));
     }

     virtual void getConstantColorComponents(GrColor* color,
                                             uint32_t* validFlags) const SK_OVERRIDE {
         if (fRect.isEmpty()) {
             // An empty rect will have no coverage anywhere.
             *color = 0x00000000;
             *validFlags = kRGBA_GrColorComponentFlags;
         } else {
             *validFlags = 0;
         }
     }

     GrConvexPolyEffect::EdgeType getEdgeType() const { return fEdgeType; }

     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;

 private:
     AARectEffect(EdgeType edgeType, const SkRect& rect) : fRect(rect), fEdgeType(edgeType) {
         this->setWillReadFragmentPosition();
     }

     virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
         const AARectEffect& aare = CastEffect<AARectEffect>(other);
         return fRect == aare.fRect;
     }

     SkRect fRect;
     EdgeType fEdgeType;

     typedef GrEffect INHERITED;

     GR_DECLARE_EFFECT_TEST;

 };

 GR_DEFINE_EFFECT_TEST(AARectEffect);

 GrEffectRef* AARectEffect::TestCreate(SkRandom* random,
                                       GrContext*,
                                       const GrDrawTargetCaps& caps,
                                       GrTexture*[]) {
     EdgeType edgeType = static_cast<EdgeType>(
                                     random->nextULessThan(GrConvexPolyEffect::kEdgeTypeCnt));

     SkRect rect = SkRect::MakeLTRB(random->nextSScalar1(),
                                    random->nextSScalar1(),
                                    random->nextSScalar1(),
                                    random->nextSScalar1());
     return AARectEffect::Create(edgeType, rect);
 }

 //////////////////////////////////////////////////////////////////////////////

 class GLAARectEffect : public GrGLEffect {
 public:
     GLAARectEffect(const GrBackendEffectFactory&, const GrDrawEffect&);

     virtual void emitCode(GrGLShaderBuilder* builder,
                           const GrDrawEffect& drawEffect,
                           EffectKey key,
                           const char* outputColor,
                           const char* inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) SK_OVERRIDE;

     static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);

     virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;

 private:
     GrGLUniformManager::UniformHandle   fRectUniform;
     SkRect                              fPrevRect;
     typedef GrGLEffect INHERITED;
 };

 GLAARectEffect::GLAARectEffect(const GrBackendEffectFactory& factory,
                                const GrDrawEffect& drawEffect)
     : INHERITED (factory) {
     fPrevRect.fLeft = SK_ScalarNaN;
 }

 void GLAARectEffect::emitCode(GrGLShaderBuilder* builder,
                               const GrDrawEffect& drawEffect,
                               EffectKey key,
                               const char* outputColor,
                               const char* inputColor,
                               const TransformedCoordsArray&,
                               const TextureSamplerArray& samplers) {
     const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
     const char *rectName;
     // The rect uniform's xyzw refer to (left + 0.5, top + 0.5, right - 0.5, bottom - 0.5),
     // respectively.
     fRectUniform = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
                                        kVec4f_GrSLType,
                                        "rect",
                                        &rectName);
     const char* fragmentPos = builder->fragmentPosition();
     if (GrConvexPolyEffect::kFillAA_EdgeType == aare.getEdgeType() ||
         GrConvexPolyEffect::kInverseFillAA_EdgeType == aare.getEdgeType()) {
         // The amount of coverage removed in x and y by the edges is computed as a pair of negative
         // numbers, xSub and ySub.
         builder->fsCodeAppend("\t\tfloat xSub, ySub;\n");
         builder->fsCodeAppendf("\t\txSub = min(%s.x - %s.x, 0.0);\n", fragmentPos, rectName);
         builder->fsCodeAppendf("\t\txSub += min(%s.z - %s.x, 0.0);\n", rectName, fragmentPos);
         builder->fsCodeAppendf("\t\tySub = min(%s.y - %s.y, 0.0);\n", fragmentPos, rectName);
         builder->fsCodeAppendf("\t\tySub += min(%s.w - %s.y, 0.0);\n", rectName, fragmentPos);
         // Now compute coverage in x and y and multiply them to get the fraction of the pixel
         // covered.
         builder->fsCodeAppendf("\t\tfloat alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));\n");
     } else {
         builder->fsCodeAppendf("\t\tfloat alpha = 1.0;\n");
         builder->fsCodeAppendf("\t\talpha *= (%s.x - %s.x) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
         builder->fsCodeAppendf("\t\talpha *= (%s.z - %s.x) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
         builder->fsCodeAppendf("\t\talpha *= (%s.y - %s.y) > 0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
         builder->fsCodeAppendf("\t\talpha *= (%s.w - %s.y) > 0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
     }

     if (GrConvexPolyEffect::kInverseFillAA_EdgeType == aare.getEdgeType() ||
         GrConvexPolyEffect::kInverseFillNoAA_EdgeType == aare.getEdgeType()) {
         builder->fsCodeAppend("\t\talpha = 1.0 - alpha;\n");
     }
     builder->fsCodeAppendf("\t\t%s = %s;\n", outputColor,
                            (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
 }

 void GLAARectEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
     const SkRect& rect = aare.getRect();
     if (rect != fPrevRect) {
         uman.set4f(fRectUniform, rect.fLeft + 0.5f, rect.fTop + 0.5f,
                    rect.fRight - 0.5f, rect.fBottom - 0.5f);
         fPrevRect = rect;
     }
 }

 GrGLEffect::EffectKey GLAARectEffect::GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
     const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
     return aare.getEdgeType();
 }

 const GrBackendEffectFactory& AARectEffect::getFactory() const {
     return GrTBackendEffectFactory<AARectEffect>::getInstance();
 }

 //////////////////////////////////////////////////////////////////////////////

 class GrGLConvexPolyEffect : public GrGLEffect {
 public:
     GrGLConvexPolyEffect(const GrBackendEffectFactory&, const GrDrawEffect&);

     virtual void emitCode(GrGLShaderBuilder* builder,
                           const GrDrawEffect& drawEffect,
                           EffectKey key,
                           const char* outputColor,
                           const char* inputColor,
                           const TransformedCoordsArray&,
                           const TextureSamplerArray&) SK_OVERRIDE;

     static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);

     virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;

 private:
     GrGLUniformManager::UniformHandle   fEdgeUniform;
     SkScalar                            fPrevEdges[3 * GrConvexPolyEffect::kMaxEdges];
     typedef GrGLEffect INHERITED;
 };

 GrGLConvexPolyEffect::GrGLConvexPolyEffect(const GrBackendEffectFactory& factory,
                                            const GrDrawEffect& drawEffect)
     : INHERITED (factory) {
     fPrevEdges[0] = SK_ScalarNaN;
 }

 void GrGLConvexPolyEffect::emitCode(GrGLShaderBuilder* builder,
                                     const GrDrawEffect& drawEffect,
                                     EffectKey key,
                                     const char* outputColor,
                                     const char* inputColor,
                                     const TransformedCoordsArray&,
                                     const TextureSamplerArray& samplers) {
     const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();

     const char *edgeArrayName;
     fEdgeUniform = builder->addUniformArray(GrGLShaderBuilder::kFragment_Visibility,
                                             kVec3f_GrSLType,
                                             "edges",
                                             cpe.getEdgeCount(),
                                             &edgeArrayName);
     builder->fsCodeAppend("\t\tfloat alpha = 1.0;\n");
     builder->fsCodeAppend("\t\tfloat edge;\n");
     const char* fragmentPos = builder->fragmentPosition();
     for (int i = 0; i < cpe.getEdgeCount(); ++i) {
         builder->fsCodeAppendf("\t\tedge = dot(%s[%d], vec3(%s.x, %s.y, 1));\n",
                                edgeArrayName, i, fragmentPos, fragmentPos);
         switch (cpe.getEdgeType()) {
             case GrConvexPolyEffect::kFillAA_EdgeType:
             case GrConvexPolyEffect::kInverseFillAA_EdgeType: // inverse handled at the end
                 builder->fsCodeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
                 break;
             case GrConvexPolyEffect::kFillNoAA_EdgeType:
             case GrConvexPolyEffect::kInverseFillNoAA_EdgeType: // inverse handled at the end
                 builder->fsCodeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
                 break;
         }
         builder->fsCodeAppend("\t\talpha *= edge;\n");
     }

     // Woe is me. See skbug.com/2149.
     if (kTegra2_GrGLRenderer == builder->ctxInfo().renderer()) {
         builder->fsCodeAppend("\t\tif (-1.0 == alpha) {\n\t\t\tdiscard;\n\t\t}\n");
     }

     if (GrConvexPolyEffect::kInverseFillAA_EdgeType == cpe.getEdgeType() ||
         GrConvexPolyEffect::kInverseFillNoAA_EdgeType == cpe.getEdgeType() ) {
         builder->fsCodeAppend("\talpha = 1.0 - alpha;\n");
     }
     builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
                            (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
 }

 void GrGLConvexPolyEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
     size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
     if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
         uman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
         memcpy(fPrevEdges, cpe.getEdges(), byteSize);
     }
 }

 GrGLEffect::EffectKey GrGLConvexPolyEffect::GenKey(const GrDrawEffect& drawEffect,
                                                    const GrGLCaps&) {
     const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
     GR_STATIC_ASSERT(GrConvexPolyEffect::kEdgeTypeCnt <= 4);
     return (cpe.getEdgeCount() << 2) | cpe.getEdgeType();
 }

 //////////////////////////////////////////////////////////////////////////////

 GrEffectRef* GrConvexPolyEffect::Create(EdgeType type, const SkPath& path, const SkVector* offset) {
     if (path.getSegmentMasks() != SkPath::kLine_SegmentMask ||
         !path.isConvex() ||
         path.isInverseFillType()) {
         return NULL;
     }

     if (path.countPoints() > kMaxEdges) {
         return NULL;
     }

     SkPoint pts[kMaxEdges];
     SkScalar edges[3 * kMaxEdges];

     SkPath::Direction dir;
     SkAssertResult(path.cheapComputeDirection(&dir));

     SkVector t;
     if (NULL == offset) {
         t.set(0, 0);
     } else {
         t = *offset;
     }

     int count = path.getPoints(pts, kMaxEdges);
     int n = 0;
     for (int lastPt = count - 1, i = 0; i < count; lastPt = i++) {
         if (pts[lastPt] != pts[i]) {
             SkVector v = pts[i] - pts[lastPt];
             v.normalize();
             if (SkPath::kCCW_Direction == dir) {
                 edges[3 * n] = v.fY;
                 edges[3 * n + 1] = -v.fX;
             } else {
                 edges[3 * n] = -v.fY;
                 edges[3 * n + 1] = v.fX;
             }
             SkPoint p = pts[i] + t;
             edges[3 * n + 2] = -(edges[3 * n] * p.fX + edges[3 * n + 1] * p.fY);
             ++n;
         }
     }
     return Create(type, n, edges);
 }

 GrEffectRef* GrConvexPolyEffect::Create(EdgeType edgeType, const SkRect& rect) {
     return AARectEffect::Create(edgeType, rect);
 }

 GrConvexPolyEffect::~GrConvexPolyEffect() {}

 void GrConvexPolyEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
     *validFlags = 0;
 }

 const GrBackendEffectFactory& GrConvexPolyEffect::getFactory() const {
     return GrTBackendEffectFactory<GrConvexPolyEffect>::getInstance();
 }

 GrConvexPolyEffect::GrConvexPolyEffect(EdgeType edgeType, int n, const SkScalar edges[])
     : fEdgeType(edgeType)
     , fEdgeCount(n) {
     // Factory function should have already ensured this.
     SkASSERT(n <= kMaxEdges);
     memcpy(fEdges, edges, 3 * n * sizeof(SkScalar));
     // Outset the edges by 0.5 so that a pixel with center on an edge is 50% covered in the AA case
     // and 100% covered in the non-AA case.
     for (int i = 0; i < n; ++i) {
         fEdges[3 * i + 2] += SK_ScalarHalf;
     }
     this->setWillReadFragmentPosition();
 }

 bool GrConvexPolyEffect::onIsEqual(const GrEffect& other) const {
     const GrConvexPolyEffect& cpe = CastEffect<GrConvexPolyEffect>(other);
     // ignore the fact that 0 == -0 and just use memcmp.
     return (cpe.fEdgeType == fEdgeType && cpe.fEdgeCount == fEdgeCount &&
             0 == memcmp(cpe.fEdges, fEdges, 3 * fEdgeCount * sizeof(SkScalar)));
 }

 //////////////////////////////////////////////////////////////////////////////

 GR_DEFINE_EFFECT_TEST(GrConvexPolyEffect);

 GrEffectRef* GrConvexPolyEffect::TestCreate(SkRandom* random,
                                             GrContext*,
                                             const GrDrawTargetCaps& caps,
                                             GrTexture*[]) {
     EdgeType edgeType = static_cast<EdgeType>(random->nextULessThan(kEdgeTypeCnt));
     int count = random->nextULessThan(kMaxEdges) + 1;
     SkScalar edges[kMaxEdges * 3];
     for (int i = 0; i < 3 * count; ++i) {
         edges[i] = random->nextSScalar1();
     }

     return GrConvexPolyEffect::Create(edgeType, count, edges);
 }
	/*
	* Copyright 2014 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "GrConvexPolyEffect.h"

	#include "gl/GrGLEffect.h"
	#include "gl/GrGLSL.h"
	#include "GrTBackendEffectFactory.h"

	#include "SkPath.h"

	//////////////////////////////////////////////////////////////////////////////
	class GLAARectEffect;

	class AARectEffect : public GrEffect {
	public:
	typedef GLAARectEffect GLEffect;
	typedef GrConvexPolyEffect::EdgeType EdgeType;

	const SkRect& getRect() const { return fRect; }

	static const char* Name() { return "AARect"; }

	static GrEffectRef* Create(EdgeType edgeType, const SkRect& rect) {
	return CreateEffectRef(AutoEffectUnref(SkNEW_ARGS(AARectEffect, (edgeType, rect))));
	}

	virtual void getConstantColorComponents(GrColor* color,
	uint32_t* validFlags) const SK_OVERRIDE {
	if (fRect.isEmpty()) {
	// An empty rect will have no coverage anywhere.
	*color = 0x00000000;
	*validFlags = kRGBA_GrColorComponentFlags;
	} else {
	*validFlags = 0;
	}
	}

	GrConvexPolyEffect::EdgeType getEdgeType() const { return fEdgeType; }

	virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;

	private:
	AARectEffect(EdgeType edgeType, const SkRect& rect) : fRect(rect), fEdgeType(edgeType) {
	this->setWillReadFragmentPosition();
	}

	virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
	const AARectEffect& aare = CastEffect<AARectEffect>(other);
	return fRect == aare.fRect;
	}

	SkRect fRect;
	EdgeType fEdgeType;

	typedef GrEffect INHERITED;

	GR_DECLARE_EFFECT_TEST;

	};

	GR_DEFINE_EFFECT_TEST(AARectEffect);

	GrEffectRef* AARectEffect::TestCreate(SkRandom* random,
	GrContext*,
	const GrDrawTargetCaps& caps,
	GrTexture*[]) {
	EdgeType edgeType = static_cast<EdgeType>(
	random->nextULessThan(GrConvexPolyEffect::kEdgeTypeCnt));

	SkRect rect = SkRect::MakeLTRB(random->nextSScalar1(),
	random->nextSScalar1(),
	random->nextSScalar1(),
	random->nextSScalar1());
	return AARectEffect::Create(edgeType, rect);
	}

	//////////////////////////////////////////////////////////////////////////////

	class GLAARectEffect : public GrGLEffect {
	public:
	GLAARectEffect(const GrBackendEffectFactory&, const GrDrawEffect&);

	virtual void emitCode(GrGLShaderBuilder* builder,
	const GrDrawEffect& drawEffect,
	EffectKey key,
	const char* outputColor,
	const char* inputColor,
	const TransformedCoordsArray&,
	const TextureSamplerArray&) SK_OVERRIDE;

	static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);

	virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;

	private:
	GrGLUniformManager::UniformHandle fRectUniform;
	SkRect fPrevRect;
	typedef GrGLEffect INHERITED;
	};

	GLAARectEffect::GLAARectEffect(const GrBackendEffectFactory& factory,
	const GrDrawEffect& drawEffect)
	: INHERITED (factory) {
	fPrevRect.fLeft = SK_ScalarNaN;
	}

	void GLAARectEffect::emitCode(GrGLShaderBuilder* builder,
	const GrDrawEffect& drawEffect,
	EffectKey key,
	const char* outputColor,
	const char* inputColor,
	const TransformedCoordsArray&,
	const TextureSamplerArray& samplers) {
	const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
	const char *rectName;
	// The rect uniform's xyzw refer to (left + 0.5, top + 0.5, right - 0.5, bottom - 0.5),
	// respectively.
	fRectUniform = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
	kVec4f_GrSLType,
	"rect",
	&rectName);
	const char* fragmentPos = builder->fragmentPosition();
	if (GrConvexPolyEffect::kFillAA_EdgeType == aare.getEdgeType() \|\|
	GrConvexPolyEffect::kInverseFillAA_EdgeType == aare.getEdgeType()) {
	// The amount of coverage removed in x and y by the edges is computed as a pair of negative
	// numbers, xSub and ySub.
	builder->fsCodeAppend("\t\tfloat xSub, ySub;\n");
	builder->fsCodeAppendf("\t\txSub = min(%s.x - %s.x, 0.0);\n", fragmentPos, rectName);
	builder->fsCodeAppendf("\t\txSub += min(%s.z - %s.x, 0.0);\n", rectName, fragmentPos);
	builder->fsCodeAppendf("\t\tySub = min(%s.y - %s.y, 0.0);\n", fragmentPos, rectName);
	builder->fsCodeAppendf("\t\tySub += min(%s.w - %s.y, 0.0);\n", rectName, fragmentPos);
	// Now compute coverage in x and y and multiply them to get the fraction of the pixel
	// covered.
	builder->fsCodeAppendf("\t\tfloat alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));\n");
	} else {
	builder->fsCodeAppendf("\t\tfloat alpha = 1.0;\n");
	builder->fsCodeAppendf("\t\talpha *= (%s.x - %s.x) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
	builder->fsCodeAppendf("\t\talpha *= (%s.z - %s.x) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
	builder->fsCodeAppendf("\t\talpha *= (%s.y - %s.y) > 0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
	builder->fsCodeAppendf("\t\talpha *= (%s.w - %s.y) > 0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
	}

	if (GrConvexPolyEffect::kInverseFillAA_EdgeType == aare.getEdgeType() \|\|
	GrConvexPolyEffect::kInverseFillNoAA_EdgeType == aare.getEdgeType()) {
	builder->fsCodeAppend("\t\talpha = 1.0 - alpha;\n");
	}
	builder->fsCodeAppendf("\t\t%s = %s;\n", outputColor,
	(GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
	}

	void GLAARectEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
	const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
	const SkRect& rect = aare.getRect();
	if (rect != fPrevRect) {
	uman.set4f(fRectUniform, rect.fLeft + 0.5f, rect.fTop + 0.5f,
	rect.fRight - 0.5f, rect.fBottom - 0.5f);
	fPrevRect = rect;
	}
	}

	GrGLEffect::EffectKey GLAARectEffect::GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
	const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
	return aare.getEdgeType();
	}

	const GrBackendEffectFactory& AARectEffect::getFactory() const {
	return GrTBackendEffectFactory<AARectEffect>::getInstance();
	}

	//////////////////////////////////////////////////////////////////////////////

	class GrGLConvexPolyEffect : public GrGLEffect {
	public:
	GrGLConvexPolyEffect(const GrBackendEffectFactory&, const GrDrawEffect&);

	virtual void emitCode(GrGLShaderBuilder* builder,
	const GrDrawEffect& drawEffect,
	EffectKey key,
	const char* outputColor,
	const char* inputColor,
	const TransformedCoordsArray&,
	const TextureSamplerArray&) SK_OVERRIDE;

	static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);

	virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;

	private:
	GrGLUniformManager::UniformHandle fEdgeUniform;
	SkScalar fPrevEdges[3 * GrConvexPolyEffect::kMaxEdges];
	typedef GrGLEffect INHERITED;
	};

	GrGLConvexPolyEffect::GrGLConvexPolyEffect(const GrBackendEffectFactory& factory,
	const GrDrawEffect& drawEffect)
	: INHERITED (factory) {
	fPrevEdges[0] = SK_ScalarNaN;
	}

	void GrGLConvexPolyEffect::emitCode(GrGLShaderBuilder* builder,
	const GrDrawEffect& drawEffect,
	EffectKey key,
	const char* outputColor,
	const char* inputColor,
	const TransformedCoordsArray&,
	const TextureSamplerArray& samplers) {
	const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();

	const char *edgeArrayName;
	fEdgeUniform = builder->addUniformArray(GrGLShaderBuilder::kFragment_Visibility,
	kVec3f_GrSLType,
	"edges",
	cpe.getEdgeCount(),
	&edgeArrayName);
	builder->fsCodeAppend("\t\tfloat alpha = 1.0;\n");
	builder->fsCodeAppend("\t\tfloat edge;\n");
	const char* fragmentPos = builder->fragmentPosition();
	for (int i = 0; i < cpe.getEdgeCount(); ++i) {
	builder->fsCodeAppendf("\t\tedge = dot(%s[%d], vec3(%s.x, %s.y, 1));\n",
	edgeArrayName, i, fragmentPos, fragmentPos);
	switch (cpe.getEdgeType()) {
	case GrConvexPolyEffect::kFillAA_EdgeType:
	case GrConvexPolyEffect::kInverseFillAA_EdgeType: // inverse handled at the end
	builder->fsCodeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
	break;
	case GrConvexPolyEffect::kFillNoAA_EdgeType:
	case GrConvexPolyEffect::kInverseFillNoAA_EdgeType: // inverse handled at the end
	builder->fsCodeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
	break;
	}
	builder->fsCodeAppend("\t\talpha *= edge;\n");
	}

	// Woe is me. See skbug.com/2149.
	if (kTegra2_GrGLRenderer == builder->ctxInfo().renderer()) {
	builder->fsCodeAppend("\t\tif (-1.0 == alpha) {\n\t\t\tdiscard;\n\t\t}\n");
	}

	if (GrConvexPolyEffect::kInverseFillAA_EdgeType == cpe.getEdgeType() \|\|
	GrConvexPolyEffect::kInverseFillNoAA_EdgeType == cpe.getEdgeType() ) {
	builder->fsCodeAppend("\talpha = 1.0 - alpha;\n");
	}
	builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
	(GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
	}

	void GrGLConvexPolyEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
	const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
	size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
	if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
	uman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
	memcpy(fPrevEdges, cpe.getEdges(), byteSize);
	}
	}

	GrGLEffect::EffectKey GrGLConvexPolyEffect::GenKey(const GrDrawEffect& drawEffect,
	const GrGLCaps&) {
	const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
	GR_STATIC_ASSERT(GrConvexPolyEffect::kEdgeTypeCnt <= 4);
	return (cpe.getEdgeCount() << 2) \| cpe.getEdgeType();
	}

	//////////////////////////////////////////////////////////////////////////////

	GrEffectRef* GrConvexPolyEffect::Create(EdgeType type, const SkPath& path, const SkVector* offset) {
	if (path.getSegmentMasks() != SkPath::kLine_SegmentMask \|\|
	!path.isConvex() \|\|
	path.isInverseFillType()) {
	return NULL;
	}

	if (path.countPoints() > kMaxEdges) {
	return NULL;
	}

	SkPoint pts[kMaxEdges];
	SkScalar edges[3 * kMaxEdges];

	SkPath::Direction dir;
	SkAssertResult(path.cheapComputeDirection(&dir));

	SkVector t;
	if (NULL == offset) {
	t.set(0, 0);
	} else {
	t = *offset;
	}

	int count = path.getPoints(pts, kMaxEdges);
	int n = 0;
	for (int lastPt = count - 1, i = 0; i < count; lastPt = i++) {
	if (pts[lastPt] != pts[i]) {
	SkVector v = pts[i] - pts[lastPt];
	v.normalize();
	if (SkPath::kCCW_Direction == dir) {
	edges[3 * n] = v.fY;
	edges[3 * n + 1] = -v.fX;
	} else {
	edges[3 * n] = -v.fY;
	edges[3 * n + 1] = v.fX;
	}
	SkPoint p = pts[i] + t;
	edges[3 * n + 2] = -(edges[3 * n] * p.fX + edges[3 * n + 1] * p.fY);
	++n;
	}
	}
	return Create(type, n, edges);
	}

	GrEffectRef* GrConvexPolyEffect::Create(EdgeType edgeType, const SkRect& rect) {
	return AARectEffect::Create(edgeType, rect);
	}

	GrConvexPolyEffect::~GrConvexPolyEffect() {}

	void GrConvexPolyEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
	*validFlags = 0;
	}

	const GrBackendEffectFactory& GrConvexPolyEffect::getFactory() const {
	return GrTBackendEffectFactory<GrConvexPolyEffect>::getInstance();
	}

	GrConvexPolyEffect::GrConvexPolyEffect(EdgeType edgeType, int n, const SkScalar edges[])
	: fEdgeType(edgeType)
	, fEdgeCount(n) {
	// Factory function should have already ensured this.
	SkASSERT(n <= kMaxEdges);
	memcpy(fEdges, edges, 3 * n * sizeof(SkScalar));
	// Outset the edges by 0.5 so that a pixel with center on an edge is 50% covered in the AA case
	// and 100% covered in the non-AA case.
	for (int i = 0; i < n; ++i) {
	fEdges[3 * i + 2] += SK_ScalarHalf;
	}
	this->setWillReadFragmentPosition();
	}

	bool GrConvexPolyEffect::onIsEqual(const GrEffect& other) const {
	const GrConvexPolyEffect& cpe = CastEffect<GrConvexPolyEffect>(other);
	// ignore the fact that 0 == -0 and just use memcmp.
	return (cpe.fEdgeType == fEdgeType && cpe.fEdgeCount == fEdgeCount &&
	0 == memcmp(cpe.fEdges, fEdges, 3 * fEdgeCount * sizeof(SkScalar)));
	}

	//////////////////////////////////////////////////////////////////////////////

	GR_DEFINE_EFFECT_TEST(GrConvexPolyEffect);

	GrEffectRef* GrConvexPolyEffect::TestCreate(SkRandom* random,
	GrContext*,
	const GrDrawTargetCaps& caps,
	GrTexture*[]) {
	EdgeType edgeType = static_cast<EdgeType>(random->nextULessThan(kEdgeTypeCnt));
	int count = random->nextULessThan(kMaxEdges) + 1;
	SkScalar edges[kMaxEdges * 3];
	for (int i = 0; i < 3 * count; ++i) {
	edges[i] = random->nextSScalar1();
	}

	return GrConvexPolyEffect::Create(edgeType, count, edges);
	}