PathModule

Detailed Description

This module defines the basic classes used to represent and manipulate light paths throughout Fermat, particularly:

• Path : represent a light path in compact form, storing its vertex ids only
• BidirPath : represent a bidirectional path in compact form, storing its vertex ids only

Classes
struct	Path
struct	BidirPath
struct	PathCache< T >
struct	BsdfInverse

Macros
#define	MAXIMUM_INVERSION_ERROR   1.0e-6f
#define	TRANSFORM_PDF(_p, _w, _w_norm)   (_p *= _w_norm / _w)

Functions
template<typename TRandomGenerator , typename BsdfComponent >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	invert_layer (const BsdfComponent &bsdf_comp, const VertexGeometry &v_prev, const cugar::Vector3f &in, const cugar::Vector3f &out, TRandomGenerator &random, cugar::Vector3f &z, float &p, float &p_proj)
template<typename TRandomGenerator >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	invert_bsdf (const Bsdf &bsdf, const VertexGeometry &v_prev, const cugar::Vector3f &in, const cugar::Vector3f &out, TRandomGenerator &random, cugar::Vector3f &z, float &p, float &p_proj, bool RR=true)
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE void	inversion_pdf (const Bsdf &bsdf, const VertexGeometry &v_prev, const cugar::Vector3f &in, const cugar::Vector3f &out, cugar::Vector3f &z, float &p, float &p_proj)
template<typename PathType , typename TRandomGenerator >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	invert_eye_subpath (const PathType &path, const uint32 t, const uint32 t_ext, float *out_Z, float *out_pdf, const RenderingContextView &renderer, TRandomGenerator &random)
template<typename PathType >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float	eye_subpath_inversion_pdf (const PathType &path, const uint32 t, const uint32 t_ext, const float *out_Z, const RenderingContextView &renderer)
template<typename PathType , typename TRandomGenerator >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	invert_light_subpath (const PathType &path, const uint32 s, const uint32 s_ext, float *out_Z, float *out_pdf, const RenderingContextView &renderer, TRandomGenerator &random)
template<typename PathType >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float	light_subpath_inversion_pdf (const PathType &path, const uint32 s, const uint32 s_ext, const float *out_Z, const RenderingContextView &renderer)
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE void	BsdfInverse::setup (ComponentSelectionStrategy _strategy, const Bsdf &bsdf, const VertexGeometry &geom, const cugar::Vector3f &in, const cugar::Vector3f &out, const bool _RR=false)
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	BsdfInverse::precompute_component_selection_coefficients ()
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE Bsdf::ComponentType	BsdfInverse::sample_component (const float v) const
template<typename TRandomGenerator >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	BsdfInverse::invert (const Bsdf &bsdf, const VertexGeometry &geom, const cugar::Vector3f &in, const cugar::Vector3f &out, TRandomGenerator &random, cugar::Vector3f &z, BsdfInverse::PdfType pdf_type=BsdfInverse::kDirectTransformPdf, float *p=NULL, float *p_proj=NULL)
template<typename TRandomGenerator >
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	BsdfInverse::invert_component (const Bsdf &bsdf, const VertexGeometry &geom, const cugar::Vector3f &in, const cugar::Vector3f &out, const Bsdf::ComponentType out_comp, TRandomGenerator &random, cugar::Vector3f &z, const bool output_global_coordinates=true)
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float	BsdfInverse::pdf (const Bsdf::ComponentType out_comp, cugar::SphericalMeasure measure=cugar::kProjectedSolidAngle, const bool weighted=false) const
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float	BsdfInverse::pdf_comp (const Bsdf::ComponentType out_comp) const
FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float	BsdfInverse::weight (const Bsdf::ComponentType out_comp) const

Function Documentation

invert()

template<typename TRandomGenerator >

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool BsdfInverse::invert	(	const Bsdf &	bsdf,
		const VertexGeometry &	geom,
		const cugar::Vector3f &	in,
		const cugar::Vector3f &	out,
		TRandomGenerator &	random,
		cugar::Vector3f &	z,
		BsdfInverse::PdfType	pdf_type = BsdfInverse::kDirectTransformPdf,
		float *	p = NULL,
		float *	p_proj = NULL
	)

invert a bsdf by randomly chosing a component

invert_component()

template<typename TRandomGenerator >

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool BsdfInverse::invert_component	(	const Bsdf &	bsdf,
		const VertexGeometry &	geom,
		const cugar::Vector3f &	in,
		const cugar::Vector3f &	out,
		const Bsdf::ComponentType	out_comp,
		TRandomGenerator &	random,
		cugar::Vector3f &	z,
		const bool	output_global_coordinates = true
	)

invert a given component of a bsdf

pdf()

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float BsdfInverse::pdf	(	const Bsdf::ComponentType	out_comp,
		cugar::SphericalMeasure	measure = cugar::kProjectedSolidAngle,
		const bool	weighted = false
	)		const

return the Jacobian determinant of the inverse transform for a given component; note that the returned Jacobian determinant is equal to the pdf of sampling that component, by definition of pdf of a transformed variable. In fact, if U is a uniform r.v. in the primary sample space, and X is the transformed path space variable, X = T(U), we have:

P(X) = P(T_inv(X)) * |J[T_inv](X)| = P(U) * |J[T_inv](X)| = |J[T_inv](X)|

pdf_comp()

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float BsdfInverse::pdf_comp

(

const Bsdf::ComponentType

out_comp

)

const

return the pdf with which a given component is selected by the inversion method.

sample_component()

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE Bsdf::ComponentType BsdfInverse::sample_component

(

const float

v

)

const

sample a component given a random number

setup()

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE void BsdfInverse::setup	(	ComponentSelectionStrategy	_strategy,
		const Bsdf &	bsdf,
		const VertexGeometry &	geom,
		const cugar::Vector3f &	in,
		const cugar::Vector3f &	out,
		const bool	_RR = false
	)

setup the inverter for a specific bsdf and geometry configuration: note that all subsequent calls to other methods of this class need to use the same configuration, unless setup() is called again with different parameters

weight()

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE float BsdfInverse::weight

(

const Bsdf::ComponentType

out_comp

)

const

return the sampling weight applied to a given component.