src/gpu/effects/GrBezierEffect.h - platform/external/skia - Gitiles

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #ifndef GrBezierEffect_DEFINED
 #define GrBezierEffect_DEFINED

 #include "GrCaps.h"
 #include "GrProcessor.h"
 #include "GrGeometryProcessor.h"
 #include "GrInvariantOutput.h"
 #include "GrTypesPriv.h"

 /**
  * Shader is based off of Loop-Blinn Quadratic GPU Rendering
  * The output of this effect is a hairline edge for conics.
  * Conics specified by implicit equation K^2 - LM.
  * K, L, and M, are the first three values of the vertex attribute,
  * the fourth value is not used. Distance is calculated using a
  * first order approximation from the taylor series.
  * Coverage for AA is max(0, 1-distance).
  *
  * Test were also run using a second order distance approximation.
  * There were two versions of the second order approx. The first version
  * is of roughly the form:
  * f(q) = |f(p)| - ||f'(p)||*||q-p|| - ||f''(p)||*||q-p||^2.
  * The second is similar:
  * f(q) = |f(p)| + ||f'(p)||*||q-p|| + ||f''(p)||*||q-p||^2.
  * The exact version of the equations can be found in the paper
  * "Distance Approximations for Rasterizing Implicit Curves" by Gabriel Taubin
  *
  * In both versions we solve the quadratic for ||q-p||.
  * Version 1:
  * gFM is magnitude of first partials and gFM2 is magnitude of 2nd partials (as derived from paper)
  * builder->fsCodeAppend("\t\tedgeAlpha = (sqrt(gFM*gFM+4.0*func*gF2M) - gFM)/(2.0*gF2M);\n");
  * Version 2:
  * builder->fsCodeAppend("\t\tedgeAlpha = (gFM - sqrt(gFM*gFM-4.0*func*gF2M))/(2.0*gF2M);\n");
  *
  * Also note that 2nd partials of k,l,m are zero
  *
  * When comparing the two second order approximations to the first order approximations,
  * the following results were found. Version 1 tends to underestimate the distances, thus it
  * basically increases all the error that we were already seeing in the first order
  * approx. So this version is not the one to use. Version 2 has the opposite effect
  * and tends to overestimate the distances. This is much closer to what we are
  * looking for. It is able to render ellipses (even thin ones) without the need to chop.
  * However, it can not handle thin hyperbolas well and thus would still rely on
  * chopping to tighten the clipping. Another side effect of the overestimating is
  * that the curves become much thinner and "ropey". If all that was ever rendered
  * were "not too thin" curves and ellipses then 2nd order may have an advantage since
  * only one geometry would need to be rendered. However no benches were run comparing
  * chopped first order and non chopped 2nd order.
  */
 class GrGLConicEffect;

 class GrConicEffect : public GrGeometryProcessor {
 public:
     static GrGeometryProcessor* Create(GrColor color,
                                        const SkMatrix& viewMatrix,
                                        const GrPrimitiveEdgeType edgeType,
                                        const GrCaps& caps,
                                        const SkMatrix& localMatrix,
                                        bool usesLocalCoords,
                                        uint8_t coverage = 0xff) {
         switch (edgeType) {
             case kFillAA_GrProcessorEdgeType:
                 if (!caps.shaderCaps()->shaderDerivativeSupport()) {
                     return nullptr;
                 }
                 return new GrConicEffect(color, viewMatrix, coverage, kFillAA_GrProcessorEdgeType,
                                          localMatrix, usesLocalCoords);
             case kHairlineAA_GrProcessorEdgeType:
                 if (!caps.shaderCaps()->shaderDerivativeSupport()) {
                     return nullptr;
                 }
                 return new GrConicEffect(color, viewMatrix, coverage,
                                          kHairlineAA_GrProcessorEdgeType, localMatrix,
                                          usesLocalCoords);
             case kFillBW_GrProcessorEdgeType:
                 return new GrConicEffect(color, viewMatrix, coverage, kFillBW_GrProcessorEdgeType,
                                          localMatrix, usesLocalCoords);
             default:
                 return nullptr;
         }
     }

     virtual ~GrConicEffect();

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

     inline const Attribute* inPosition() const { return fInPosition; }
     inline const Attribute* inConicCoeffs() const { return fInConicCoeffs; }
     inline bool isAntiAliased() const { return GrProcessorEdgeTypeIsAA(fEdgeType); }
     inline bool isFilled() const { return GrProcessorEdgeTypeIsFill(fEdgeType); }
     inline GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
     GrColor color() const { return fColor; }
     bool colorIgnored() const { return GrColor_ILLEGAL == fColor; }
     const SkMatrix& viewMatrix() const { return fViewMatrix; }
     const SkMatrix& localMatrix() const { return fLocalMatrix; }
     bool usesLocalCoords() const { return fUsesLocalCoords; }
     uint8_t coverageScale() const { return fCoverageScale; }

     void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;

     GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override;

 private:
     GrConicEffect(GrColor, const SkMatrix& viewMatrix, uint8_t coverage, GrPrimitiveEdgeType,
                   const SkMatrix& localMatrix, bool usesLocalCoords);

     GrColor             fColor;
     SkMatrix            fViewMatrix;
     SkMatrix            fLocalMatrix;
     bool                fUsesLocalCoords;
     uint8_t             fCoverageScale;
     GrPrimitiveEdgeType fEdgeType;
     const Attribute*    fInPosition;
     const Attribute*    fInConicCoeffs;

     GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

     typedef GrGeometryProcessor INHERITED;
 };

 ///////////////////////////////////////////////////////////////////////////////
 /**
  * The output of this effect is a hairline edge for quadratics.
  * Quadratic specified by 0=u^2-v canonical coords. u and v are the first
  * two components of the vertex attribute. At the three control points that define
  * the Quadratic, u, v have the values {0,0}, {1/2, 0}, and {1, 1} respectively.
  * Coverage for AA is min(0, 1-distance). 3rd & 4th cimponent unused.
  * Requires shader derivative instruction support.
  */
 class GrGLQuadEffect;

 class GrQuadEffect : public GrGeometryProcessor {
 public:
     static GrGeometryProcessor* Create(GrColor color,
                                        const SkMatrix& viewMatrix,
                                        const GrPrimitiveEdgeType edgeType,
                                        const GrCaps& caps,
                                        const SkMatrix& localMatrix,
                                        bool usesLocalCoords,
                                        uint8_t coverage = 0xff) {
         switch (edgeType) {
             case kFillAA_GrProcessorEdgeType:
                 if (!caps.shaderCaps()->shaderDerivativeSupport()) {
                     return nullptr;
                 }
                 return new GrQuadEffect(color, viewMatrix, coverage, kFillAA_GrProcessorEdgeType,
                                         localMatrix, usesLocalCoords);
             case kHairlineAA_GrProcessorEdgeType:
                 if (!caps.shaderCaps()->shaderDerivativeSupport()) {
                     return nullptr;
                 }
                 return new GrQuadEffect(color, viewMatrix, coverage,
                                         kHairlineAA_GrProcessorEdgeType, localMatrix,
                                         usesLocalCoords);
             case kFillBW_GrProcessorEdgeType:
                 return new GrQuadEffect(color, viewMatrix, coverage, kFillBW_GrProcessorEdgeType,
                                         localMatrix, usesLocalCoords);
             default:
                 return nullptr;
         }
     }

     virtual ~GrQuadEffect();

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

     inline const Attribute* inPosition() const { return fInPosition; }
     inline const Attribute* inHairQuadEdge() const { return fInHairQuadEdge; }
     inline bool isAntiAliased() const { return GrProcessorEdgeTypeIsAA(fEdgeType); }
     inline bool isFilled() const { return GrProcessorEdgeTypeIsFill(fEdgeType); }
     inline GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
     GrColor color() const { return fColor; }
     bool colorIgnored() const { return GrColor_ILLEGAL == fColor; }
     const SkMatrix& viewMatrix() const { return fViewMatrix; }
     const SkMatrix& localMatrix() const { return fLocalMatrix; }
     bool usesLocalCoords() const { return fUsesLocalCoords; }
     uint8_t coverageScale() const { return fCoverageScale; }

     void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;

     GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override;

 private:
     GrQuadEffect(GrColor, const SkMatrix& viewMatrix, uint8_t coverage, GrPrimitiveEdgeType,
                  const SkMatrix& localMatrix, bool usesLocalCoords);

     GrColor             fColor;
     SkMatrix            fViewMatrix;
     SkMatrix            fLocalMatrix;
     bool                fUsesLocalCoords;
     uint8_t             fCoverageScale;
     GrPrimitiveEdgeType fEdgeType;
     const Attribute*    fInPosition;
     const Attribute*    fInHairQuadEdge;

     GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

     typedef GrGeometryProcessor INHERITED;
 };

 //////////////////////////////////////////////////////////////////////////////
 /**
  * Shader is based off of "Resolution Independent Curve Rendering using
  * Programmable Graphics Hardware" by Loop and Blinn.
  * The output of this effect is a hairline edge for non rational cubics.
  * Cubics are specified by implicit equation K^3 - LM.
  * K, L, and M, are the first three values of the vertex attribute,
  * the fourth value is not used. Distance is calculated using a
  * first order approximation from the taylor series.
  * Coverage for AA is max(0, 1-distance).
  */
 class GrGLCubicEffect;

 class GrCubicEffect : public GrGeometryProcessor {
 public:
     static GrGeometryProcessor* Create(GrColor color,
                                        const SkMatrix& viewMatrix,
                                        const GrPrimitiveEdgeType edgeType,
                                        const GrCaps& caps) {
         switch (edgeType) {
             case kFillAA_GrProcessorEdgeType:
                 if (!caps.shaderCaps()->shaderDerivativeSupport()) {
                     return nullptr;
                 }
                 return new GrCubicEffect(color, viewMatrix, kFillAA_GrProcessorEdgeType);
             case kHairlineAA_GrProcessorEdgeType:
                 if (!caps.shaderCaps()->shaderDerivativeSupport()) {
                     return nullptr;
                 }
                 return new GrCubicEffect(color, viewMatrix, kHairlineAA_GrProcessorEdgeType);
             case kFillBW_GrProcessorEdgeType:
                 return new GrCubicEffect(color, viewMatrix, kFillBW_GrProcessorEdgeType);
             default:
                 return nullptr;
         }
     }

     virtual ~GrCubicEffect();

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

     inline const Attribute* inPosition() const { return fInPosition; }
     inline const Attribute* inCubicCoeffs() const { return fInCubicCoeffs; }
     inline bool isAntiAliased() const { return GrProcessorEdgeTypeIsAA(fEdgeType); }
     inline bool isFilled() const { return GrProcessorEdgeTypeIsFill(fEdgeType); }
     inline GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
     GrColor color() const { return fColor; }
     bool colorIgnored() const { return GrColor_ILLEGAL == fColor; }
     const SkMatrix& viewMatrix() const { return fViewMatrix; }

     void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;

     GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override;

 private:
     GrCubicEffect(GrColor, const SkMatrix& viewMatrix, GrPrimitiveEdgeType);

     GrColor             fColor;
     SkMatrix            fViewMatrix;
     GrPrimitiveEdgeType fEdgeType;
     const Attribute*    fInPosition;
     const Attribute*    fInCubicCoeffs;

     GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

     typedef GrGeometryProcessor INHERITED;
 };

 #endif
	/*
	* Copyright 2013 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#ifndef GrBezierEffect_DEFINED
	#define GrBezierEffect_DEFINED

	#include "GrCaps.h"
	#include "GrProcessor.h"
	#include "GrGeometryProcessor.h"
	#include "GrInvariantOutput.h"
	#include "GrTypesPriv.h"

	/**
	* Shader is based off of Loop-Blinn Quadratic GPU Rendering
	* The output of this effect is a hairline edge for conics.
	* Conics specified by implicit equation K^2 - LM.
	* K, L, and M, are the first three values of the vertex attribute,
	* the fourth value is not used. Distance is calculated using a
	* first order approximation from the taylor series.
	* Coverage for AA is max(0, 1-distance).
	*
	* Test were also run using a second order distance approximation.
	* There were two versions of the second order approx. The first version
	* is of roughly the form:
	* f(q) = \|f(p)\| - \|\|f'(p)\|\|\|\|q-p\|\| - \|\|f''(p)\|\|\|\|q-p\|\|^2.
	* The second is similar:
	* f(q) = \|f(p)\| + \|\|f'(p)\|\|\|\|q-p\|\| + \|\|f''(p)\|\|\|\|q-p\|\|^2.
	* The exact version of the equations can be found in the paper
	* "Distance Approximations for Rasterizing Implicit Curves" by Gabriel Taubin
	*
	* In both versions we solve the quadratic for \|\|q-p\|\|.
	* Version 1:
	* gFM is magnitude of first partials and gFM2 is magnitude of 2nd partials (as derived from paper)
	* builder->fsCodeAppend("\t\tedgeAlpha = (sqrt(gFMgFM+4.0funcgF2M) - gFM)/(2.0gF2M);\n");
	* Version 2:
	* builder->fsCodeAppend("\t\tedgeAlpha = (gFM - sqrt(gFMgFM-4.0funcgF2M))/(2.0gF2M);\n");
	*
	* Also note that 2nd partials of k,l,m are zero
	*
	* When comparing the two second order approximations to the first order approximations,
	* the following results were found. Version 1 tends to underestimate the distances, thus it
	* basically increases all the error that we were already seeing in the first order
	* approx. So this version is not the one to use. Version 2 has the opposite effect
	* and tends to overestimate the distances. This is much closer to what we are
	* looking for. It is able to render ellipses (even thin ones) without the need to chop.
	* However, it can not handle thin hyperbolas well and thus would still rely on
	* chopping to tighten the clipping. Another side effect of the overestimating is
	* that the curves become much thinner and "ropey". If all that was ever rendered
	* were "not too thin" curves and ellipses then 2nd order may have an advantage since
	* only one geometry would need to be rendered. However no benches were run comparing
	* chopped first order and non chopped 2nd order.
	*/
	class GrGLConicEffect;

	class GrConicEffect : public GrGeometryProcessor {
	public:
	static GrGeometryProcessor* Create(GrColor color,
	const SkMatrix& viewMatrix,
	const GrPrimitiveEdgeType edgeType,
	const GrCaps& caps,
	const SkMatrix& localMatrix,
	bool usesLocalCoords,
	uint8_t coverage = 0xff) {
	switch (edgeType) {
	case kFillAA_GrProcessorEdgeType:
	if (!caps.shaderCaps()->shaderDerivativeSupport()) {
	return nullptr;
	}
	return new GrConicEffect(color, viewMatrix, coverage, kFillAA_GrProcessorEdgeType,
	localMatrix, usesLocalCoords);
	case kHairlineAA_GrProcessorEdgeType:
	if (!caps.shaderCaps()->shaderDerivativeSupport()) {
	return nullptr;
	}
	return new GrConicEffect(color, viewMatrix, coverage,
	kHairlineAA_GrProcessorEdgeType, localMatrix,
	usesLocalCoords);
	case kFillBW_GrProcessorEdgeType:
	return new GrConicEffect(color, viewMatrix, coverage, kFillBW_GrProcessorEdgeType,
	localMatrix, usesLocalCoords);
	default:
	return nullptr;
	}
	}

	virtual ~GrConicEffect();

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

	inline const Attribute* inPosition() const { return fInPosition; }
	inline const Attribute* inConicCoeffs() const { return fInConicCoeffs; }
	inline bool isAntiAliased() const { return GrProcessorEdgeTypeIsAA(fEdgeType); }
	inline bool isFilled() const { return GrProcessorEdgeTypeIsFill(fEdgeType); }
	inline GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
	GrColor color() const { return fColor; }
	bool colorIgnored() const { return GrColor_ILLEGAL == fColor; }
	const SkMatrix& viewMatrix() const { return fViewMatrix; }
	const SkMatrix& localMatrix() const { return fLocalMatrix; }
	bool usesLocalCoords() const { return fUsesLocalCoords; }
	uint8_t coverageScale() const { return fCoverageScale; }

	void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;

	GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override;

	private:
	GrConicEffect(GrColor, const SkMatrix& viewMatrix, uint8_t coverage, GrPrimitiveEdgeType,
	const SkMatrix& localMatrix, bool usesLocalCoords);

	GrColor fColor;
	SkMatrix fViewMatrix;
	SkMatrix fLocalMatrix;
	bool fUsesLocalCoords;
	uint8_t fCoverageScale;
	GrPrimitiveEdgeType fEdgeType;
	const Attribute* fInPosition;
	const Attribute* fInConicCoeffs;

	GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

	typedef GrGeometryProcessor INHERITED;
	};

	///////////////////////////////////////////////////////////////////////////////
	/**
	* The output of this effect is a hairline edge for quadratics.
	* Quadratic specified by 0=u^2-v canonical coords. u and v are the first
	* two components of the vertex attribute. At the three control points that define
	* the Quadratic, u, v have the values {0,0}, {1/2, 0}, and {1, 1} respectively.
	* Coverage for AA is min(0, 1-distance). 3rd & 4th cimponent unused.
	* Requires shader derivative instruction support.
	*/
	class GrGLQuadEffect;

	class GrQuadEffect : public GrGeometryProcessor {
	public:
	static GrGeometryProcessor* Create(GrColor color,
	const SkMatrix& viewMatrix,
	const GrPrimitiveEdgeType edgeType,
	const GrCaps& caps,
	const SkMatrix& localMatrix,
	bool usesLocalCoords,
	uint8_t coverage = 0xff) {
	switch (edgeType) {
	case kFillAA_GrProcessorEdgeType:
	if (!caps.shaderCaps()->shaderDerivativeSupport()) {
	return nullptr;
	}
	return new GrQuadEffect(color, viewMatrix, coverage, kFillAA_GrProcessorEdgeType,
	localMatrix, usesLocalCoords);
	case kHairlineAA_GrProcessorEdgeType:
	if (!caps.shaderCaps()->shaderDerivativeSupport()) {
	return nullptr;
	}
	return new GrQuadEffect(color, viewMatrix, coverage,
	kHairlineAA_GrProcessorEdgeType, localMatrix,
	usesLocalCoords);
	case kFillBW_GrProcessorEdgeType:
	return new GrQuadEffect(color, viewMatrix, coverage, kFillBW_GrProcessorEdgeType,
	localMatrix, usesLocalCoords);
	default:
	return nullptr;
	}
	}

	virtual ~GrQuadEffect();

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

	inline const Attribute* inPosition() const { return fInPosition; }
	inline const Attribute* inHairQuadEdge() const { return fInHairQuadEdge; }
	inline bool isAntiAliased() const { return GrProcessorEdgeTypeIsAA(fEdgeType); }
	inline bool isFilled() const { return GrProcessorEdgeTypeIsFill(fEdgeType); }
	inline GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
	GrColor color() const { return fColor; }
	bool colorIgnored() const { return GrColor_ILLEGAL == fColor; }
	const SkMatrix& viewMatrix() const { return fViewMatrix; }
	const SkMatrix& localMatrix() const { return fLocalMatrix; }
	bool usesLocalCoords() const { return fUsesLocalCoords; }
	uint8_t coverageScale() const { return fCoverageScale; }

	void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;

	GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override;

	private:
	GrQuadEffect(GrColor, const SkMatrix& viewMatrix, uint8_t coverage, GrPrimitiveEdgeType,
	const SkMatrix& localMatrix, bool usesLocalCoords);

	GrColor fColor;
	SkMatrix fViewMatrix;
	SkMatrix fLocalMatrix;
	bool fUsesLocalCoords;
	uint8_t fCoverageScale;
	GrPrimitiveEdgeType fEdgeType;
	const Attribute* fInPosition;
	const Attribute* fInHairQuadEdge;

	GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

	typedef GrGeometryProcessor INHERITED;
	};

	//////////////////////////////////////////////////////////////////////////////
	/**
	* Shader is based off of "Resolution Independent Curve Rendering using
	* Programmable Graphics Hardware" by Loop and Blinn.
	* The output of this effect is a hairline edge for non rational cubics.
	* Cubics are specified by implicit equation K^3 - LM.
	* K, L, and M, are the first three values of the vertex attribute,
	* the fourth value is not used. Distance is calculated using a
	* first order approximation from the taylor series.
	* Coverage for AA is max(0, 1-distance).
	*/
	class GrGLCubicEffect;

	class GrCubicEffect : public GrGeometryProcessor {
	public:
	static GrGeometryProcessor* Create(GrColor color,
	const SkMatrix& viewMatrix,
	const GrPrimitiveEdgeType edgeType,
	const GrCaps& caps) {
	switch (edgeType) {
	case kFillAA_GrProcessorEdgeType:
	if (!caps.shaderCaps()->shaderDerivativeSupport()) {
	return nullptr;
	}
	return new GrCubicEffect(color, viewMatrix, kFillAA_GrProcessorEdgeType);
	case kHairlineAA_GrProcessorEdgeType:
	if (!caps.shaderCaps()->shaderDerivativeSupport()) {
	return nullptr;
	}
	return new GrCubicEffect(color, viewMatrix, kHairlineAA_GrProcessorEdgeType);
	case kFillBW_GrProcessorEdgeType:
	return new GrCubicEffect(color, viewMatrix, kFillBW_GrProcessorEdgeType);
	default:
	return nullptr;
	}
	}

	virtual ~GrCubicEffect();

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

	inline const Attribute* inPosition() const { return fInPosition; }
	inline const Attribute* inCubicCoeffs() const { return fInCubicCoeffs; }
	inline bool isAntiAliased() const { return GrProcessorEdgeTypeIsAA(fEdgeType); }
	inline bool isFilled() const { return GrProcessorEdgeTypeIsFill(fEdgeType); }
	inline GrPrimitiveEdgeType getEdgeType() const { return fEdgeType; }
	GrColor color() const { return fColor; }
	bool colorIgnored() const { return GrColor_ILLEGAL == fColor; }
	const SkMatrix& viewMatrix() const { return fViewMatrix; }

	void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;

	GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override;

	private:
	GrCubicEffect(GrColor, const SkMatrix& viewMatrix, GrPrimitiveEdgeType);

	GrColor fColor;
	SkMatrix fViewMatrix;
	GrPrimitiveEdgeType fEdgeType;
	const Attribute* fInPosition;
	const Attribute* fInCubicCoeffs;

	GR_DECLARE_GEOMETRY_PROCESSOR_TEST;

	typedef GrGeometryProcessor INHERITED;
	};

	#endif