Isotropic Beckmann distribution. See the paper "Microfacet Models for Refraction through Rough Surfaces" by Walter et al. [18]. More...
#include <IsoBeckmann.h>
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()
|
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()
|
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()
|
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()
|
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 generatedH.distribution()is not a probability density of microfacet normal.
Implements ph::ShapeInvariantMicrofacet.
The documentation for this class was generated from the following files:
- Source/Core/SurfaceBehavior/Property/IsoBeckmann.h
- Source/Core/SurfaceBehavior/Property/IsoBeckmann.cpp
