src/gpu/effects/GrConvexPolyEffect.cpp - platform/external/skia - 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 "GrInvariantOutput.h"
 #include "SkPathPriv.h"
 #include "gl/GrGLContext.h"
 #include "gl/GrGLFragmentProcessor.h"
 #include "gl/builders/GrGLProgramBuilder.h"

 //////////////////////////////////////////////////////////////////////////////
 class AARectEffect : public GrFragmentProcessor {
 public:
     const SkRect& getRect() const { return fRect; }

     static GrFragmentProcessor* Create(GrPrimitiveEdgeType edgeType, const SkRect& rect) {
         return new AARectEffect(edgeType, rect);
     }

     GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }

     const char* name() const override { return "AARect"; }

     void onGetGLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder*) const override;

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

     GrGLFragmentProcessor* onCreateGLInstance() const override;

     bool onIsEqual(const GrFragmentProcessor& other) const override {
         const AARectEffect& aare = other.cast<AARectEffect>();
         return fRect == aare.fRect;
     }

     void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
         if (fRect.isEmpty()) {
             // An empty rect will have no coverage anywhere.
             inout->mulByKnownSingleComponent(0);
         } else {
             inout->mulByUnknownSingleComponent();
         }
     }

     SkRect              fRect;
     GrPrimitiveEdgeType fEdgeType;

     typedef GrFragmentProcessor INHERITED;

     GR_DECLARE_FRAGMENT_PROCESSOR_TEST;

 };

 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(AARectEffect);

 const GrFragmentProcessor* AARectEffect::TestCreate(GrProcessorTestData* d) {
     SkRect rect = SkRect::MakeLTRB(d->fRandom->nextSScalar1(),
                                    d->fRandom->nextSScalar1(),
                                    d->fRandom->nextSScalar1(),
                                    d->fRandom->nextSScalar1());
     GrFragmentProcessor* fp;
     do {
         GrPrimitiveEdgeType edgeType = static_cast<GrPrimitiveEdgeType>(
                 d->fRandom->nextULessThan(kGrProcessorEdgeTypeCnt));

         fp = AARectEffect::Create(edgeType, rect);
     } while (nullptr == fp);
     return fp;
 }

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

 class GLAARectEffect : public GrGLFragmentProcessor {
 public:
     GLAARectEffect(const GrProcessor&);

     virtual void emitCode(EmitArgs&) override;

     static inline void GenKey(const GrProcessor&, const GrGLSLCaps&, GrProcessorKeyBuilder*);

 protected:
     void onSetData(const GrGLProgramDataManager&, const GrProcessor&) override;

 private:
     GrGLProgramDataManager::UniformHandle fRectUniform;
     SkRect                                fPrevRect;
     typedef GrGLFragmentProcessor INHERITED;
 };

 GLAARectEffect::GLAARectEffect(const GrProcessor& effect) {
     fPrevRect.fLeft = SK_ScalarNaN;
 }

 void GLAARectEffect::emitCode(EmitArgs& args) {
     const AARectEffect& aare = args.fFp.cast<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 = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                        kVec4f_GrSLType,
                                        kDefault_GrSLPrecision,
                                        "rect",
                                        &rectName);

     GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder();
     const char* fragmentPos = fsBuilder->fragmentPosition();
     if (GrProcessorEdgeTypeIsAA(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.
         fsBuilder->codeAppend("\t\tfloat xSub, ySub;\n");
         fsBuilder->codeAppendf("\t\txSub = min(%s.x - %s.x, 0.0);\n", fragmentPos, rectName);
         fsBuilder->codeAppendf("\t\txSub += min(%s.z - %s.x, 0.0);\n", rectName, fragmentPos);
         fsBuilder->codeAppendf("\t\tySub = min(%s.y - %s.y, 0.0);\n", fragmentPos, rectName);
         fsBuilder->codeAppendf("\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.
         fsBuilder->codeAppendf("\t\tfloat alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));\n");
     } else {
         fsBuilder->codeAppendf("\t\tfloat alpha = 1.0;\n");
         fsBuilder->codeAppendf("\t\talpha *= (%s.x - %s.x) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
         fsBuilder->codeAppendf("\t\talpha *= (%s.z - %s.x) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
         fsBuilder->codeAppendf("\t\talpha *= (%s.y - %s.y) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
         fsBuilder->codeAppendf("\t\talpha *= (%s.w - %s.y) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
     }

     if (GrProcessorEdgeTypeIsInverseFill(aare.getEdgeType())) {
         fsBuilder->codeAppend("\t\talpha = 1.0 - alpha;\n");
     }
     fsBuilder->codeAppendf("\t\t%s = %s;\n", args.fOutputColor,
                            (GrGLSLExpr4(args.fInputColor) * GrGLSLExpr1("alpha")).c_str());
 }

 void GLAARectEffect::onSetData(const GrGLProgramDataManager& pdman, const GrProcessor& processor) {
     const AARectEffect& aare = processor.cast<AARectEffect>();
     const SkRect& rect = aare.getRect();
     if (rect != fPrevRect) {
         pdman.set4f(fRectUniform, rect.fLeft + 0.5f, rect.fTop + 0.5f,
                    rect.fRight - 0.5f, rect.fBottom - 0.5f);
         fPrevRect = rect;
     }
 }

 void GLAARectEffect::GenKey(const GrProcessor& processor, const GrGLSLCaps&,
                             GrProcessorKeyBuilder* b) {
     const AARectEffect& aare = processor.cast<AARectEffect>();
     b->add32(aare.getEdgeType());
 }

 void AARectEffect::onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
     GLAARectEffect::GenKey(*this, caps, b);
 }

 GrGLFragmentProcessor* AARectEffect::onCreateGLInstance() const  {
     return new GLAARectEffect(*this);
 }

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

 class GrGLConvexPolyEffect : public GrGLFragmentProcessor {
 public:
     GrGLConvexPolyEffect(const GrProcessor&);

     virtual void emitCode(EmitArgs&) override;

     static inline void GenKey(const GrProcessor&, const GrGLSLCaps&, GrProcessorKeyBuilder*);

 protected:
     void onSetData(const GrGLProgramDataManager&, const GrProcessor&) override;

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

 GrGLConvexPolyEffect::GrGLConvexPolyEffect(const GrProcessor&) {
     fPrevEdges[0] = SK_ScalarNaN;
 }

 void GrGLConvexPolyEffect::emitCode(EmitArgs& args) {
     const GrConvexPolyEffect& cpe = args.fFp.cast<GrConvexPolyEffect>();

     const char *edgeArrayName;
     fEdgeUniform = args.fBuilder->addUniformArray(GrGLProgramBuilder::kFragment_Visibility,
                                             kVec3f_GrSLType,
                                              kDefault_GrSLPrecision,
                                              "edges",
                                             cpe.getEdgeCount(),
                                             &edgeArrayName);
     GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder();
     fsBuilder->codeAppend("\t\tfloat alpha = 1.0;\n");
     fsBuilder->codeAppend("\t\tfloat edge;\n");
     const char* fragmentPos = fsBuilder->fragmentPosition();
     for (int i = 0; i < cpe.getEdgeCount(); ++i) {
         fsBuilder->codeAppendf("\t\tedge = dot(%s[%d], vec3(%s.x, %s.y, 1));\n",
                                edgeArrayName, i, fragmentPos, fragmentPos);
         if (GrProcessorEdgeTypeIsAA(cpe.getEdgeType())) {
             fsBuilder->codeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
         } else {
             fsBuilder->codeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
         }
         fsBuilder->codeAppend("\t\talpha *= edge;\n");
     }

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

     if (GrProcessorEdgeTypeIsInverseFill(cpe.getEdgeType())) {
         fsBuilder->codeAppend("\talpha = 1.0 - alpha;\n");
     }
     fsBuilder->codeAppendf("\t%s = %s;\n", args.fOutputColor,
                            (GrGLSLExpr4(args.fInputColor) * GrGLSLExpr1("alpha")).c_str());
 }

 void GrGLConvexPolyEffect::onSetData(const GrGLProgramDataManager& pdman, const GrProcessor& effect) {
     const GrConvexPolyEffect& cpe = effect.cast<GrConvexPolyEffect>();
     size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
     if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
         pdman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
         memcpy(fPrevEdges, cpe.getEdges(), byteSize);
     }
 }

 void GrGLConvexPolyEffect::GenKey(const GrProcessor& processor, const GrGLSLCaps&,
                                   GrProcessorKeyBuilder* b) {
     const GrConvexPolyEffect& cpe = processor.cast<GrConvexPolyEffect>();
     GR_STATIC_ASSERT(kGrProcessorEdgeTypeCnt <= 8);
     uint32_t key = (cpe.getEdgeCount() << 3) | cpe.getEdgeType();
     b->add32(key);
 }

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

 GrFragmentProcessor* GrConvexPolyEffect::Create(GrPrimitiveEdgeType type, const SkPath& path,
                                                 const SkVector* offset) {
     if (kHairlineAA_GrProcessorEdgeType == type) {
         return nullptr;
     }
     if (path.getSegmentMasks() != SkPath::kLine_SegmentMask ||
         !path.isConvex()) {
         return nullptr;
     }

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

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

     SkPathPriv::FirstDirection dir;
     SkAssertResult(SkPathPriv::CheapComputeFirstDirection(path, &dir));

     SkVector t;
     if (nullptr == 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 (SkPathPriv::kCCW_FirstDirection == 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;
         }
     }
     if (path.isInverseFillType()) {
         type = GrInvertProcessorEdgeType(type);
     }
     return Create(type, n, edges);
 }

 GrFragmentProcessor* GrConvexPolyEffect::Create(GrPrimitiveEdgeType edgeType, const SkRect& rect) {
     if (kHairlineAA_GrProcessorEdgeType == edgeType){
         return nullptr;
     }
     return AARectEffect::Create(edgeType, rect);
 }

 GrConvexPolyEffect::~GrConvexPolyEffect() {}

 void GrConvexPolyEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
     inout->mulByUnknownSingleComponent();
 }

 void GrConvexPolyEffect::onGetGLProcessorKey(const GrGLSLCaps& caps,
                                            GrProcessorKeyBuilder* b) const {
     GrGLConvexPolyEffect::GenKey(*this, caps, b);
 }

 GrGLFragmentProcessor* GrConvexPolyEffect::onCreateGLInstance() const  {
     return new GrGLConvexPolyEffect(*this);
 }

 GrConvexPolyEffect::GrConvexPolyEffect(GrPrimitiveEdgeType edgeType, int n, const SkScalar edges[])
     : fEdgeType(edgeType)
     , fEdgeCount(n) {
     this->initClassID<GrConvexPolyEffect>();
     // 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 GrFragmentProcessor& other) const {
     const GrConvexPolyEffect& cpe = other.cast<GrConvexPolyEffect>();
     // 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_FRAGMENT_PROCESSOR_TEST(GrConvexPolyEffect);

 const GrFragmentProcessor* GrConvexPolyEffect::TestCreate(GrProcessorTestData* d) {
     int count = d->fRandom->nextULessThan(kMaxEdges) + 1;
     SkScalar edges[kMaxEdges * 3];
     for (int i = 0; i < 3 * count; ++i) {
         edges[i] = d->fRandom->nextSScalar1();
     }

     GrFragmentProcessor* fp;
     do {
         GrPrimitiveEdgeType edgeType = static_cast<GrPrimitiveEdgeType>(
                 d->fRandom->nextULessThan(kGrProcessorEdgeTypeCnt));
         fp = GrConvexPolyEffect::Create(edgeType, count, edges);
     } while (nullptr == fp);
     return fp;
 }
	/*
	* 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 "GrInvariantOutput.h"
	#include "SkPathPriv.h"
	#include "gl/GrGLContext.h"
	#include "gl/GrGLFragmentProcessor.h"
	#include "gl/builders/GrGLProgramBuilder.h"

	//////////////////////////////////////////////////////////////////////////////
	class AARectEffect : public GrFragmentProcessor {
	public:
	const SkRect& getRect() const { return fRect; }

	static GrFragmentProcessor* Create(GrPrimitiveEdgeType edgeType, const SkRect& rect) {
	return new AARectEffect(edgeType, rect);
	}

	GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }

	const char* name() const override { return "AARect"; }

	void onGetGLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder*) const override;

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

	GrGLFragmentProcessor* onCreateGLInstance() const override;

	bool onIsEqual(const GrFragmentProcessor& other) const override {
	const AARectEffect& aare = other.cast<AARectEffect>();
	return fRect == aare.fRect;
	}

	void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
	if (fRect.isEmpty()) {
	// An empty rect will have no coverage anywhere.
	inout->mulByKnownSingleComponent(0);
	} else {
	inout->mulByUnknownSingleComponent();
	}
	}

	SkRect fRect;
	GrPrimitiveEdgeType fEdgeType;

	typedef GrFragmentProcessor INHERITED;

	GR_DECLARE_FRAGMENT_PROCESSOR_TEST;

	};

	GR_DEFINE_FRAGMENT_PROCESSOR_TEST(AARectEffect);

	const GrFragmentProcessor* AARectEffect::TestCreate(GrProcessorTestData* d) {
	SkRect rect = SkRect::MakeLTRB(d->fRandom->nextSScalar1(),
	d->fRandom->nextSScalar1(),
	d->fRandom->nextSScalar1(),
	d->fRandom->nextSScalar1());
	GrFragmentProcessor* fp;
	do {
	GrPrimitiveEdgeType edgeType = static_cast<GrPrimitiveEdgeType>(
	d->fRandom->nextULessThan(kGrProcessorEdgeTypeCnt));

	fp = AARectEffect::Create(edgeType, rect);
	} while (nullptr == fp);
	return fp;
	}

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

	class GLAARectEffect : public GrGLFragmentProcessor {
	public:
	GLAARectEffect(const GrProcessor&);

	virtual void emitCode(EmitArgs&) override;

	static inline void GenKey(const GrProcessor&, const GrGLSLCaps&, GrProcessorKeyBuilder*);

	protected:
	void onSetData(const GrGLProgramDataManager&, const GrProcessor&) override;

	private:
	GrGLProgramDataManager::UniformHandle fRectUniform;
	SkRect fPrevRect;
	typedef GrGLFragmentProcessor INHERITED;
	};

	GLAARectEffect::GLAARectEffect(const GrProcessor& effect) {
	fPrevRect.fLeft = SK_ScalarNaN;
	}

	void GLAARectEffect::emitCode(EmitArgs& args) {
	const AARectEffect& aare = args.fFp.cast<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 = args.fBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
	kVec4f_GrSLType,
	kDefault_GrSLPrecision,
	"rect",
	&rectName);

	GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder();
	const char* fragmentPos = fsBuilder->fragmentPosition();
	if (GrProcessorEdgeTypeIsAA(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.
	fsBuilder->codeAppend("\t\tfloat xSub, ySub;\n");
	fsBuilder->codeAppendf("\t\txSub = min(%s.x - %s.x, 0.0);\n", fragmentPos, rectName);
	fsBuilder->codeAppendf("\t\txSub += min(%s.z - %s.x, 0.0);\n", rectName, fragmentPos);
	fsBuilder->codeAppendf("\t\tySub = min(%s.y - %s.y, 0.0);\n", fragmentPos, rectName);
	fsBuilder->codeAppendf("\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.
	fsBuilder->codeAppendf("\t\tfloat alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));\n");
	} else {
	fsBuilder->codeAppendf("\t\tfloat alpha = 1.0;\n");
	fsBuilder->codeAppendf("\t\talpha *= (%s.x - %s.x) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
	fsBuilder->codeAppendf("\t\talpha *= (%s.z - %s.x) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
	fsBuilder->codeAppendf("\t\talpha *= (%s.y - %s.y) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
	fsBuilder->codeAppendf("\t\talpha *= (%s.w - %s.y) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
	}

	if (GrProcessorEdgeTypeIsInverseFill(aare.getEdgeType())) {
	fsBuilder->codeAppend("\t\talpha = 1.0 - alpha;\n");
	}
	fsBuilder->codeAppendf("\t\t%s = %s;\n", args.fOutputColor,
	(GrGLSLExpr4(args.fInputColor) * GrGLSLExpr1("alpha")).c_str());
	}

	void GLAARectEffect::onSetData(const GrGLProgramDataManager& pdman, const GrProcessor& processor) {
	const AARectEffect& aare = processor.cast<AARectEffect>();
	const SkRect& rect = aare.getRect();
	if (rect != fPrevRect) {
	pdman.set4f(fRectUniform, rect.fLeft + 0.5f, rect.fTop + 0.5f,
	rect.fRight - 0.5f, rect.fBottom - 0.5f);
	fPrevRect = rect;
	}
	}

	void GLAARectEffect::GenKey(const GrProcessor& processor, const GrGLSLCaps&,
	GrProcessorKeyBuilder* b) {
	const AARectEffect& aare = processor.cast<AARectEffect>();
	b->add32(aare.getEdgeType());
	}

	void AARectEffect::onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
	GLAARectEffect::GenKey(*this, caps, b);
	}

	GrGLFragmentProcessor* AARectEffect::onCreateGLInstance() const {
	return new GLAARectEffect(*this);
	}

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

	class GrGLConvexPolyEffect : public GrGLFragmentProcessor {
	public:
	GrGLConvexPolyEffect(const GrProcessor&);

	virtual void emitCode(EmitArgs&) override;

	static inline void GenKey(const GrProcessor&, const GrGLSLCaps&, GrProcessorKeyBuilder*);

	protected:
	void onSetData(const GrGLProgramDataManager&, const GrProcessor&) override;

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

	GrGLConvexPolyEffect::GrGLConvexPolyEffect(const GrProcessor&) {
	fPrevEdges[0] = SK_ScalarNaN;
	}

	void GrGLConvexPolyEffect::emitCode(EmitArgs& args) {
	const GrConvexPolyEffect& cpe = args.fFp.cast<GrConvexPolyEffect>();

	const char *edgeArrayName;
	fEdgeUniform = args.fBuilder->addUniformArray(GrGLProgramBuilder::kFragment_Visibility,
	kVec3f_GrSLType,
	kDefault_GrSLPrecision,
	"edges",
	cpe.getEdgeCount(),
	&edgeArrayName);
	GrGLFragmentBuilder* fsBuilder = args.fBuilder->getFragmentShaderBuilder();
	fsBuilder->codeAppend("\t\tfloat alpha = 1.0;\n");
	fsBuilder->codeAppend("\t\tfloat edge;\n");
	const char* fragmentPos = fsBuilder->fragmentPosition();
	for (int i = 0; i < cpe.getEdgeCount(); ++i) {
	fsBuilder->codeAppendf("\t\tedge = dot(%s[%d], vec3(%s.x, %s.y, 1));\n",
	edgeArrayName, i, fragmentPos, fragmentPos);
	if (GrProcessorEdgeTypeIsAA(cpe.getEdgeType())) {
	fsBuilder->codeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
	} else {
	fsBuilder->codeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
	}
	fsBuilder->codeAppend("\t\talpha *= edge;\n");
	}

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

	if (GrProcessorEdgeTypeIsInverseFill(cpe.getEdgeType())) {
	fsBuilder->codeAppend("\talpha = 1.0 - alpha;\n");
	}
	fsBuilder->codeAppendf("\t%s = %s;\n", args.fOutputColor,
	(GrGLSLExpr4(args.fInputColor) * GrGLSLExpr1("alpha")).c_str());
	}

	void GrGLConvexPolyEffect::onSetData(const GrGLProgramDataManager& pdman, const GrProcessor& effect) {
	const GrConvexPolyEffect& cpe = effect.cast<GrConvexPolyEffect>();
	size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
	if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
	pdman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
	memcpy(fPrevEdges, cpe.getEdges(), byteSize);
	}
	}

	void GrGLConvexPolyEffect::GenKey(const GrProcessor& processor, const GrGLSLCaps&,
	GrProcessorKeyBuilder* b) {
	const GrConvexPolyEffect& cpe = processor.cast<GrConvexPolyEffect>();
	GR_STATIC_ASSERT(kGrProcessorEdgeTypeCnt <= 8);
	uint32_t key = (cpe.getEdgeCount() << 3) \| cpe.getEdgeType();
	b->add32(key);
	}

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

	GrFragmentProcessor* GrConvexPolyEffect::Create(GrPrimitiveEdgeType type, const SkPath& path,
	const SkVector* offset) {
	if (kHairlineAA_GrProcessorEdgeType == type) {
	return nullptr;
	}
	if (path.getSegmentMasks() != SkPath::kLine_SegmentMask \|\|
	!path.isConvex()) {
	return nullptr;
	}

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

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

	SkPathPriv::FirstDirection dir;
	SkAssertResult(SkPathPriv::CheapComputeFirstDirection(path, &dir));

	SkVector t;
	if (nullptr == 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 (SkPathPriv::kCCW_FirstDirection == 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;
	}
	}
	if (path.isInverseFillType()) {
	type = GrInvertProcessorEdgeType(type);
	}
	return Create(type, n, edges);
	}

	GrFragmentProcessor* GrConvexPolyEffect::Create(GrPrimitiveEdgeType edgeType, const SkRect& rect) {
	if (kHairlineAA_GrProcessorEdgeType == edgeType){
	return nullptr;
	}
	return AARectEffect::Create(edgeType, rect);
	}

	GrConvexPolyEffect::~GrConvexPolyEffect() {}

	void GrConvexPolyEffect::onComputeInvariantOutput(GrInvariantOutput* inout) const {
	inout->mulByUnknownSingleComponent();
	}

	void GrConvexPolyEffect::onGetGLProcessorKey(const GrGLSLCaps& caps,
	GrProcessorKeyBuilder* b) const {
	GrGLConvexPolyEffect::GenKey(*this, caps, b);
	}

	GrGLFragmentProcessor* GrConvexPolyEffect::onCreateGLInstance() const {
	return new GrGLConvexPolyEffect(*this);
	}

	GrConvexPolyEffect::GrConvexPolyEffect(GrPrimitiveEdgeType edgeType, int n, const SkScalar edges[])
	: fEdgeType(edgeType)
	, fEdgeCount(n) {
	this->initClassID<GrConvexPolyEffect>();
	// 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 GrFragmentProcessor& other) const {
	const GrConvexPolyEffect& cpe = other.cast<GrConvexPolyEffect>();
	// 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_FRAGMENT_PROCESSOR_TEST(GrConvexPolyEffect);

	const GrFragmentProcessor* GrConvexPolyEffect::TestCreate(GrProcessorTestData* d) {
	int count = d->fRandom->nextULessThan(kMaxEdges) + 1;
	SkScalar edges[kMaxEdges * 3];
	for (int i = 0; i < 3 * count; ++i) {
	edges[i] = d->fRandom->nextSScalar1();
	}

	GrFragmentProcessor* fp;
	do {
	GrPrimitiveEdgeType edgeType = static_cast<GrPrimitiveEdgeType>(
	d->fRandom->nextULessThan(kGrProcessorEdgeTypeCnt));
	fp = GrConvexPolyEffect::Create(edgeType, count, edges);
	} while (nullptr == fp);
	return fp;
	}