ph::IsoBeckmann Class Reference

Isotropic Beckmann distribution. See the paper "Microfacet Models for Refraction through Rough Surfaces" by Walter et al. [18]. More...

#include <IsoBeckmann.h>

Inheritance diagram for ph::IsoBeckmann:

Public Member Functions
	IsoBeckmann (real alpha, EMaskingShadowing maskingShadowingType)
std::array< real, 2 >	getAlphas (const SurfaceHit &X) const override
real	lambda (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &H, const math::Vector3R &unitDir, const std::array< real, 2 > &alphas) const override
	The $\Lambda \left( a \right)$ function that appears in the masking-shadowing term. For isotropic distributions, the variable $a$ is normally calculated as $a = \frac{1}{\alpha \tan \left( \theta \right)}$, where $\frac{1}{\tan \left( \theta \right)}$ is the slope of the unit direction unitDir (with respect to the macrosurface normal N. For anisotropic distributions, see the implementation of AnisoTrowbridgeReitz as an example for calculating $a$ from the parameters.
real	distribution (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &H) const override
	Distribution of the microfacet normal. The $D$ term. Also commonly knwon as the NDF (normal distribution function). This term is defined in the half-angle/microfacet space (the angle between N and H) unless otherwise noted.
void	sampleH (const SurfaceHit &X, const math::Vector3R &N, const std::array< real, 2 > &sample, math::Vector3R *out_H) const override
	Generate a microfacet normal H for the distribution. This samples all possible H vectors for the distribution.
Public Member Functions inherited from ph::ShapeInvariantMicrofacet
	ShapeInvariantMicrofacet (EMaskingShadowing maskingShadowingType)
real	geometry (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &H, const math::Vector3R &L, const math::Vector3R &V) const override
	Masking and shadowing due to nearby microfacets. The $G$ term.
lta::PDF	pdfSampleH (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &H) const override
Public Member Functions inherited from ph::Microfacet
virtual	~Microfacet ()=default
virtual void	sampleVisibleH (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &V, const std::array< real, 2 > &sample, math::Vector3R *out_H) const
	Same as sampleH(), but tries to take geometry term into consideration. This samples only potentially visible H vectors for the distribution. If unable to fully or partly incorporate visibility information from the geometry term, this method will fallback to sampleH().
virtual lta::PDF	pdfSampleVisibleH (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &H, const math::Vector3R &V) const

Additional Inherited Members
Protected Member Functions inherited from ph::ShapeInvariantMicrofacet
real	smithG1 (real lambdaValue) const
real	empiricalPhiCorrelation (const SurfaceHit &X, const math::Vector3R &L, const math::Vector3R &V) const
real	projectedDistribution (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &H) const
real	visibleDistribution (const SurfaceHit &X, const math::Vector3R &N, const math::Vector3R &H, const math::Vector3R &V) const
Static Protected Member Functions inherited from ph::Microfacet
static bool	isSidednessAgreed (real NoD, real HoD)
static bool	isSidednessAgreed (real NoL, real NoV, real HoL, real HoV)
Protected Attributes inherited from ph::ShapeInvariantMicrofacet
EMaskingShadowing	m_maskingShadowingType

Detailed Description

Isotropic Beckmann distribution. See the paper "Microfacet Models for Refraction through Rough Surfaces" by Walter et al. [18].

Constructor & Destructor Documentation

IsoBeckmann()

ph::IsoBeckmann::IsoBeckmann	(	real	alpha,
		EMaskingShadowing	maskingShadowingType )

Member Function Documentation

distribution()

real ph::IsoBeckmann::distribution ( const SurfaceHit & X, const math::Vector3R & N, const math::Vector3R & H ) const

overridevirtual

Distribution of the microfacet normal. The $D$ term. Also commonly knwon as the NDF (normal distribution function). This term is defined in the half-angle/microfacet space (the angle between N and H) unless otherwise noted.

Parameters

H	The microfacet normal.

Remarks

Do not treat this term as the probability density of microfacet normal over solid angle.

Implements ph::ShapeInvariantMicrofacet.

getAlphas()

std::array< real, 2 > ph::IsoBeckmann::getAlphas ( const SurfaceHit & X ) const

inlineoverridevirtual

Returns

$\left( \alpha_u, \alpha_v \right)$ in the U and V directions of the macrosirface parametrization. Guaranteed to have $\alpha_u = \alpha_v$ for an isotropic distribution.

Implements ph::ShapeInvariantMicrofacet.

lambda()

real ph::IsoBeckmann::lambda ( const SurfaceHit & X, const math::Vector3R & N, const math::Vector3R & H, const math::Vector3R & unitDir, const std::array< real, 2 > & alphas ) const

overridevirtual

The $\Lambda \left( a \right)$ function that appears in the masking-shadowing term. For isotropic distributions, the variable $a$ is normally calculated as $a = \frac{1}{\alpha \tan \left( \theta \right)}$, where $\frac{1}{\tan \left( \theta \right)}$ is the slope of the unit direction unitDir (with respect to the macrosurface normal N. For anisotropic distributions, see the implementation of AnisoTrowbridgeReitz as an example for calculating $a$ from the parameters.

Note

This method does not handle sidedness agreement.

Implements ph::ShapeInvariantMicrofacet.

sampleH()

void ph::IsoBeckmann::sampleH ( const SurfaceHit & X, const math::Vector3R & N, const std::array< real, 2 > & sample, math::Vector3R * out_H ) const

overridevirtual

Generate a microfacet normal H for the distribution. This samples all possible H vectors for the distribution.

Parameters

out_H

The generated microfacet normal.

Remarks

Use pdfSampleH() for the probability density of sampling the generated H. distribution() is not a probability density of microfacet normal.

Implements ph::ShapeInvariantMicrofacet.

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

• Source/Core/SurfaceBehavior/Property/IsoBeckmann.h
• Source/Core/SurfaceBehavior/Property/IsoBeckmann.cpp