#include <GrBezierEffect.h>

Inheritance diagram for GrConicEffect:

Classes
class	Impl

Public Member Functions
	~GrConicEffect () override

const char *	name () const override

void	addToKey (const GrShaderCaps &caps, skgpu::KeyBuilder *b) const override

std::unique_ptr< ProgramImpl >	makeProgramImpl (const GrShaderCaps &) const override

Public Member Functions inherited from GrGeometryProcessor
	GrGeometryProcessor (ClassID)

int	numTextureSamplers () const

const TextureSampler &	textureSampler (int index) const

int	numVertexAttributes () const

const AttributeSet &	vertexAttributes () const

int	numInstanceAttributes () const

const AttributeSet &	instanceAttributes () const

bool	hasVertexAttributes () const

bool	hasInstanceAttributes () const

size_t	vertexStride () const

size_t	instanceStride () const

void	getAttributeKey (skgpu::KeyBuilder *b) const

Public Member Functions inherited from GrProcessor
virtual	~GrProcessor ()=default

void *	operator new (size_t size)

void *	operator new (size_t object_size, size_t footer_size)

void	operator delete (void *target)

void *	operator new (size_t size, void *placement)

void	operator delete (void target, void placement)

template<typename T >
const T &	cast () const

ClassID	classID () const

Static Public Member Functions
static GrGeometryProcessor *	Make (SkArenaAlloc *arena, const SkPMColor4f &color, const SkMatrix &viewMatrix, const GrCaps &caps, const SkMatrix &localMatrix, bool usesLocalCoords, uint8_t coverage=0xff)

Static Public Member Functions inherited from GrGeometryProcessor
static uint32_t	ComputeCoordTransformsKey (const GrFragmentProcessor &fp)

Additional Inherited Members
Public Types inherited from GrProcessor
enum	ClassID { kNull_ClassID , kAttributeTestProcessor_ClassID , kBigKeyProcessor_ClassID , kBlendFragmentProcessor_ClassID , kBlockInputFragmentProcessor_ClassID , kButtCapStrokedCircleGeometryProcessor_ClassID , kCircleGeometryProcessor_ClassID , kCircularRRectEffect_ClassID , kClockwiseTestProcessor_ClassID , kColorTableEffect_ClassID , kCoverageSetOpXP_ClassID , kCustomXP_ClassID , kDashingCircleEffect_ClassID , kDashingLineEffect_ClassID , kDefaultGeoProc_ClassID , kDeviceSpace_ClassID , kDIEllipseGeometryProcessor_ClassID , kDisableColorXP_ClassID , kDrawAtlasPathShader_ClassID , kEllipseGeometryProcessor_ClassID , kEllipticalRRectEffect_ClassID , kFwidthSquircleTestProcessor_ClassID , kGP_ClassID , kGrBicubicEffect_ClassID , kGrBitmapTextGeoProc_ClassID , kGrColorSpaceXformEffect_ClassID , kGrConicEffect_ClassID , kGrConvexPolyEffect_ClassID , kGrDiffuseLightingEffect_ClassID , kGrDisplacementMapEffect_ClassID , kGrDistanceFieldA8TextGeoProc_ClassID , kGrDistanceFieldLCDTextGeoProc_ClassID , kGrDistanceFieldPathGeoProc_ClassID , kGrFillRRectOp_Processor_ClassID , kGrGaussianConvolutionFragmentProcessor_ClassID , kGrMatrixConvolutionEffect_ClassID , kGrMatrixEffect_ClassID , kGrMeshTestProcessor_ClassID , kGrMorphologyEffect_ClassID , kGrPerlinNoise2Effect_ClassID , kGrPipelineDynamicStateTestProcessor_ClassID , kGrQuadEffect_ClassID , kGrRRectShadowGeoProc_ClassID , kGrSkSLFP_ClassID , kGrSpecularLightingEffect_ClassID , kGrTextureEffect_ClassID , kGrUnrolledBinaryGradientColorizer_ClassID , kGrYUVtoRGBEffect_ClassID , kHighPrecisionFragmentProcessor_ClassID , kLatticeGP_ClassID , kPDLCDXferProcessor_ClassID , kPorterDuffXferProcessor_ClassID , kPremulFragmentProcessor_ClassID , kQuadEdgeEffect_ClassID , kQuadPerEdgeAAGeometryProcessor_ClassID , kSeriesFragmentProcessor_ClassID , kShaderPDXferProcessor_ClassID , kSurfaceColorProcessor_ClassID , kSwizzleFragmentProcessor_ClassID , kTessellate_BoundingBoxShader_ClassID , kTessellate_GrModulateAtlasCoverageEffect_ClassID , kTessellate_GrStrokeTessellationShader_ClassID , kTessellate_HullShader_ClassID , kTessellate_MiddleOutShader_ClassID , kTessellate_SimpleTriangleShader_ClassID , kTessellationTestTriShader_ClassID , kTestFP_ClassID , kTestRectOp_ClassID , kVertexColorSpaceBenchGP_ClassID , kVerticesGP_ClassID }

Static Public Attributes inherited from GrGeometryProcessor
static constexpr int	kCoordTransformKeyBits = 4

Protected Member Functions inherited from GrGeometryProcessor
void	setVertexAttributes (const Attribute *attrs, int attrCount, size_t stride)

void	setInstanceAttributes (const Attribute *attrs, int attrCount, size_t stride)

void	setVertexAttributesWithImplicitOffsets (const Attribute *attrs, int attrCount)

void	setInstanceAttributesWithImplicitOffsets (const Attribute *attrs, int attrCount)

void	setTextureSamplerCnt (int cnt)

Protected Member Functions inherited from GrProcessor
	GrProcessor (ClassID classID)

	GrProcessor (const GrProcessor &)=delete

GrProcessor &	operator= (const GrProcessor &)=delete

Static Protected Member Functions inherited from GrGeometryProcessor
static Attribute	MakeColorAttribute (const char *name, bool wideColor)

Protected Attributes inherited from GrProcessor
const ClassID	fClassID

Detailed Description

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.

Definition at line 66 of file GrBezierEffect.h.

Constructor & Destructor Documentation

◆ ~GrConicEffect()

GrConicEffect::~GrConicEffect ( )

overridedefault

Member Function Documentation

◆ addToKey()

void GrConicEffect::addToKey	(	const GrShaderCaps &	,
		skgpu::KeyBuilder *
	)		const

overridevirtual

Adds a key on the skgpu::KeyBuilder that reflects any variety in the code that the geometry processor subclass can emit.

Implements GrGeometryProcessor.

Definition at line 162 of file GrBezierEffect.cpp.

                                                                               {
    uint32_t key = 0;
    key |= fCoverageScale == 0xff ? 0x8  : 0x0;
    key |= fUsesLocalCoords       ? 0x10 : 0x0;
    key = ProgramImpl::AddMatrixKeys(caps,
                                     key,
                                     fViewMatrix,
                                     fUsesLocalCoords ? fLocalMatrix : SkMatrix::I());
    b->add32(key);
}

◆ Make()

static GrGeometryProcessor * GrConicEffect::Make	(	SkArenaAlloc *	arena,
		const SkPMColor4f &	color,
		const SkMatrix &	viewMatrix,
		const GrCaps &	caps,
		const SkMatrix &	localMatrix,
		bool	usesLocalCoords,
		uint8_t	coverage = `0xff`
	)

inlinestatic

Definition at line 68 of file GrBezierEffect.h.

                                                              {
        if (!caps.shaderCaps()->fShaderDerivativeSupport) {
            return nullptr;
        }
 
        return arena->make([&](void* ptr) {
            return new (ptr) GrConicEffect(color, viewMatrix, coverage, localMatrix,
                                           usesLocalCoords);
        });
    }

◆ makeProgramImpl()

std::unique_ptr< GrGeometryProcessor::ProgramImpl > GrConicEffect::makeProgramImpl ( const GrShaderCaps & ) const

overridevirtual

Returns a new instance of the appropriate implementation class for the given GrGeometryProcessor.

Implements GrGeometryProcessor.

Definition at line 173 of file GrBezierEffect.cpp.

                                   {
    return std::make_unique<Impl>();
}

◆ name()

const char * GrConicEffect::name ( ) const

inlineoverridevirtual

Human-meaningful string to identify this processor; may be embedded in generated shader code and must be a legal SkSL identifier prefix.

Implements GrProcessor.

Definition at line 87 of file GrBezierEffect.h.

87{ return "Conic"; }

The documentation for this class was generated from the following files:

third_party/skia/src/gpu/ganesh/effects/GrBezierEffect.h
third_party/skia/src/gpu/ganesh/effects/GrBezierEffect.cpp

Classes

Public Member Functions

Static Public Member Functions

Additional Inherited Members