| /* |
| * 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 "GrEffect.h" |
| #include "GrDrawTargetCaps.h" |
| |
| enum GrBezierEdgeType { |
| kFillAA_GrBezierEdgeType, |
| kHairAA_GrBezierEdgeType, |
| kFillNoAA_GrBezierEdgeType, |
| }; |
| |
| static inline bool GrBezierEdgeTypeIsFill(const GrBezierEdgeType edgeType) { |
| return (kHairAA_GrBezierEdgeType != edgeType); |
| } |
| |
| static inline bool GrBezierEdgeTypeIsAA(const GrBezierEdgeType edgeType) { |
| return (kFillNoAA_GrBezierEdgeType != edgeType); |
| } |
| |
| /** |
| * 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 GrEffect { |
| public: |
| static GrEffectRef* Create(const GrBezierEdgeType edgeType, const GrDrawTargetCaps& caps) { |
| GR_CREATE_STATIC_EFFECT(gConicFillAA, GrConicEffect, (edgeType)); |
| GR_CREATE_STATIC_EFFECT(gConicHairAA, GrConicEffect, (edgeType)); |
| GR_CREATE_STATIC_EFFECT(gConicFillNoAA, GrConicEffect, (edgeType)); |
| if (kFillAA_GrBezierEdgeType == edgeType) { |
| if (!caps.shaderDerivativeSupport()) { |
| return NULL; |
| } |
| gConicFillAA->ref(); |
| return gConicFillAA; |
| } else if (kHairAA_GrBezierEdgeType == edgeType) { |
| if (!caps.shaderDerivativeSupport()) { |
| return NULL; |
| } |
| gConicHairAA->ref(); |
| return gConicHairAA; |
| } else { |
| gConicFillNoAA->ref(); |
| return gConicFillNoAA; |
| } |
| } |
| |
| virtual ~GrConicEffect(); |
| |
| static const char* Name() { return "Conic"; } |
| |
| inline bool isAntiAliased() const { return GrBezierEdgeTypeIsAA(fEdgeType); } |
| inline bool isFilled() const { return GrBezierEdgeTypeIsFill(fEdgeType); } |
| inline GrBezierEdgeType getEdgeType() const { return fEdgeType; } |
| |
| typedef GrGLConicEffect GLEffect; |
| |
| virtual void getConstantColorComponents(GrColor* color, |
| uint32_t* validFlags) const SK_OVERRIDE { |
| *validFlags = 0; |
| } |
| |
| virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE; |
| |
| private: |
| GrConicEffect(GrBezierEdgeType); |
| |
| virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE; |
| |
| GrBezierEdgeType fEdgeType; |
| |
| GR_DECLARE_EFFECT_TEST; |
| |
| typedef GrEffect 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 GrEffect { |
| public: |
| static GrEffectRef* Create(const GrBezierEdgeType edgeType, const GrDrawTargetCaps& caps) { |
| GR_CREATE_STATIC_EFFECT(gQuadFillAA, GrQuadEffect, (kFillAA_GrBezierEdgeType)); |
| GR_CREATE_STATIC_EFFECT(gQuadHairAA, GrQuadEffect, (kHairAA_GrBezierEdgeType)); |
| GR_CREATE_STATIC_EFFECT(gQuadFillNoAA, GrQuadEffect, (kFillNoAA_GrBezierEdgeType)); |
| if (kFillAA_GrBezierEdgeType == edgeType) { |
| if (!caps.shaderDerivativeSupport()) { |
| return NULL; |
| } |
| gQuadFillAA->ref(); |
| return gQuadFillAA; |
| } else if (kHairAA_GrBezierEdgeType == edgeType) { |
| if (!caps.shaderDerivativeSupport()) { |
| return NULL; |
| } |
| gQuadHairAA->ref(); |
| return gQuadHairAA; |
| } else { |
| gQuadFillNoAA->ref(); |
| return gQuadFillNoAA; |
| } |
| } |
| |
| virtual ~GrQuadEffect(); |
| |
| static const char* Name() { return "Quad"; } |
| |
| inline bool isAntiAliased() const { return GrBezierEdgeTypeIsAA(fEdgeType); } |
| inline bool isFilled() const { return GrBezierEdgeTypeIsFill(fEdgeType); } |
| inline GrBezierEdgeType getEdgeType() const { return fEdgeType; } |
| |
| typedef GrGLQuadEffect GLEffect; |
| |
| virtual void getConstantColorComponents(GrColor* color, |
| uint32_t* validFlags) const SK_OVERRIDE { |
| *validFlags = 0; |
| } |
| |
| virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE; |
| |
| private: |
| GrQuadEffect(GrBezierEdgeType); |
| |
| virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE; |
| |
| GrBezierEdgeType fEdgeType; |
| |
| GR_DECLARE_EFFECT_TEST; |
| |
| typedef GrEffect 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 GrEffect { |
| public: |
| static GrEffectRef* Create(const GrBezierEdgeType edgeType, const GrDrawTargetCaps& caps) { |
| GR_CREATE_STATIC_EFFECT(gCubicFillAA, GrCubicEffect, (kFillAA_GrBezierEdgeType)); |
| GR_CREATE_STATIC_EFFECT(gCubicHairAA, GrCubicEffect, (kHairAA_GrBezierEdgeType)); |
| GR_CREATE_STATIC_EFFECT(gCubicFillNoAA, GrCubicEffect, (kFillNoAA_GrBezierEdgeType)); |
| if (kFillAA_GrBezierEdgeType == edgeType) { |
| if (!caps.shaderDerivativeSupport()) { |
| return NULL; |
| } |
| gCubicFillAA->ref(); |
| return gCubicFillAA; |
| } else if (kHairAA_GrBezierEdgeType == edgeType) { |
| if (!caps.shaderDerivativeSupport()) { |
| return NULL; |
| } |
| gCubicHairAA->ref(); |
| return gCubicHairAA; |
| } else { |
| gCubicFillNoAA->ref(); |
| return gCubicFillNoAA; |
| } |
| } |
| |
| virtual ~GrCubicEffect(); |
| |
| static const char* Name() { return "Cubic"; } |
| |
| inline bool isAntiAliased() const { return GrBezierEdgeTypeIsAA(fEdgeType); } |
| inline bool isFilled() const { return GrBezierEdgeTypeIsFill(fEdgeType); } |
| inline GrBezierEdgeType getEdgeType() const { return fEdgeType; } |
| |
| typedef GrGLCubicEffect GLEffect; |
| |
| virtual void getConstantColorComponents(GrColor* color, |
| uint32_t* validFlags) const SK_OVERRIDE { |
| *validFlags = 0; |
| } |
| |
| virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE; |
| |
| private: |
| GrCubicEffect(GrBezierEdgeType); |
| |
| virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE; |
| |
| GrBezierEdgeType fEdgeType; |
| |
| GR_DECLARE_EFFECT_TEST; |
| |
| typedef GrEffect INHERITED; |
| }; |
| |
| #endif |