MaterialGGX Class Reference

CPU methods for evaluating the Cook-Torrance BRDF (Lambert+GGX/Towbridge-Reitz) for a given set of parameters, and sample a ray following the distribution of normals. More...

#include <MaterialGGX.hpp>

Public Member Functions
	MaterialGGX ()=delete

Static Public Member Functions
static glm::vec3	sampleAndEval (const glm::vec3 &wo, const glm::vec3 &baseColor, float roughness, float metallic, glm::vec3 &wi)
static glm::vec3	eval (const glm::vec3 &wo, const glm::vec3 &baseColor, float roughness, float metallic, const glm::vec3 &wi)

Static Private Member Functions
static glm::vec3	F (glm::vec3 F0, float VdotH)
static float	D (float NdotH, float alpha)
static float	V (float NdotL, float NdotV, float alpha)
static float	alphaFromRoughness (float roughness)
static glm::vec3	GGX (const glm::vec3 &wo, const glm::vec3 &baseColor, float alpha, float metallic, const glm::vec3 &wi, float *pdf)

Detailed Description

CPU methods for evaluating the Cook-Torrance BRDF (Lambert+GGX/Towbridge-Reitz) for a given set of parameters, and sample a ray following the distribution of normals.

Constructor & Destructor Documentation

MaterialGGX()

MaterialGGX::MaterialGGX ( )

delete

Constructor. (deleted)

Member Function Documentation

alphaFromRoughness()

float MaterialGGX::alphaFromRoughness ( float  roughness )

staticprivate

Convert linear roughness to perceptual.

Parameters

roughness

the linear roughness

Returns

the perceptual roughness

D()

float MaterialGGX::D ( float  NdotH, float  alpha  )

staticprivate

Evaluate the normal distribution term.

Parameters

NdotH	cosine of the angle between the surface normal and the (view,light) half vector
alpha	the surface perceptual roughness

Returns

the intensity based on the microfacets orientation.

eval()

glm::vec3 MaterialGGX::eval ( const glm::vec3 &  wo, const glm::vec3 &  baseColor, float  roughness, float  metallic, const glm::vec3 &  wi  )

static

Evaluate the BRDF value for a given set of directions and parameters. Both directions are expressed in the local frame and have the surface point as origin.

Parameters

wo	the outgoing ray direction (usually direction towards the camera)
baseColor	the surface albedo (for dieletrics) or specular tint (for conductors)
roughness	the linear roughness of the surface
metallic	the metallicness of the surface (usually 0 or 1)
wi	the incoming ray direction (usually direction towards a light/surface)

Returns

the BRDF evaluated for the sampled direction.

F()

glm::vec3 MaterialGGX::F ( glm::vec3  F0, float  VdotH  )

staticprivate

Schlick-Fresnel approximation.

Parameters

F0	Fresnel coefficient at normal incidence
VdotH	cosine of the angle between the view direction and the (view,light) half vector

Returns

the Fresnel coefficient at the given view incidence.

GGX()

glm::vec3 MaterialGGX::GGX ( const glm::vec3 &  wo, const glm::vec3 &  baseColor, float  alpha, float  metallic, const glm::vec3 &  wi, float *  pdf  )

staticprivate

Evaluate the specular GGX lobe BRDF.

Parameters

wo	the outgoing ray direction (usually direction towards the camera)
baseColor	the surface albedo (for dieletrics) or specular tint (for conductors)
alpha	the perceptual roughness of the surface
metallic	the metallicness of the surface (usually 0 or 1)
wi	the incoming ray direction (usually direction towards a light/surface)
pdf	if non null, will contain the PDF of the incoming direction

Returns

the BRDF evaluated for the sampled direction.

sampleAndEval()

glm::vec3 MaterialGGX::sampleAndEval ( const glm::vec3 &  wo, const glm::vec3 &  baseColor, float  roughness, float  metallic, glm::vec3 &  wi  )

static

Sample a random direction based on the shape of the BRDF diffuse and specular lobes. Both directions are expressed in the local frame and have the surface point as origin.

Parameters

wo	the outgoing ray direction (usually direction towards the camera)
baseColor	the surface albedo (for dieletrics) or specular tint (for conductors)
roughness	the linear roughness of the surface
metallic	the metallicness of the surface (usually 0 or 1).
wi	will contain the sampled incoming ray direction (usually direction towards a light/surface)

Returns

the BRDF evaluated for the sampled direction, weighted by its PDF

V()

float MaterialGGX::V ( float  NdotL, float  NdotV, float  alpha  )

staticprivate

Evaluate the visibility term.

Parameters

NdotL	cosine of the angle between the view direction and the light direction
NdotV	cosine of the angle between the surface normal and the view direction
alpha	the surface perceptual roughness

Returns

the intensity based on inter-shadowing of the microfacets.

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

• src/apps/pathtracer/MaterialGGX.hpp
• src/apps/pathtracer/MaterialGGX.cpp