Detailed description

Composite BSDF class

: This class defines the Bidirectional Scattering Distribution Function employed throughout Fermat. At present time, this model is rather simple, and consists of five layered components only:

a diffuse reflection component
a diffuse transmission component
a glossy reflection component layered on top of the diffuse layer
a glossy transmission component layered on top of the diffuse layer
a clearcoat layer on top of all of the above

The interaction between the top clearcoat layer and the inner layers below that is modeled approximately, computing only the Fresnel transmission factor to enter the clearcoat, but without modeling the change due to refraction of the input and output directions a la Weidlich and Wilkie. This is done because the approach from Weidlich and Wilkie simulates only first-order scattering, and results in dramatic energy loss for rough materials. It is also questionable whether that would be more correct, given that accounting for multiple-scattering through the various layers can be modeled without altering the final lobe directions, and while only changing the statistics of the inner layer distributions, as described in: "Efficient Rendering of Layered Materials using an Atomic Decomposition with Statistical Operators", Laurent Belcour - in ACM Transactions on Graphics, Association for Computing Machinery, 2018. While we plan to adopt the full machinery of the latter in the future, we currently just crudely approximate it.

The inner layers of the BSDF use Fresnel coefficients to determine how much light undergoes glossy reflection, and how much undergoes transmission. Part of the radiance transmitted from the upper glossy layer undergoes diffuse scattering. Again, the interaction between the glossy layer and the underlying diffuse layer is modeled in a simplified manner, as if the layer was infinitely thin and the diffusely reflected particles were not interacting again with the upper layer.

#include <bsdf.h>

Public Types
enum	ComponentIndex { kDiffuseReflectionIndex = 0u, kDiffuseTransmissionIndex = 1u, kGlossyReflectionIndex = 2u, kGlossyTransmissionIndex = 3u, kClearcoatReflectionIndex = 4u, kNumComponents = 5u }

enum	ComponentType { kAbsorption = 0u, kDiffuseReflection = 0x1u, kDiffuseTransmission = 0x2u, kGlossyReflection = 0x4u, kGlossyTransmission = 0x8u, kClearcoatReflection = 0x10u, kDiffuseMask = 0x3u, kGlossyMask = 0xCu, kReflectionMask = 0x5u, kTransmissionMask = 0xAu, kAllComponents = 0xFFu }

typedef cugar::LambertTransBsdf	diffuse_trans_component

typedef cugar::LambertBsdf	diffuse_component

typedef cugar::GGXSmithBsdf	glossy_component

Public Methods
FERMAT_HOST_DEVICE	Bsdf ()

FERMAT_HOST_DEVICE	Bsdf (const Bsdf &bsdf)

FERMAT_HOST_DEVICE	Bsdf (const TransportType transport, const RenderingContextView renderer, const MeshMaterial material, const float mollification_factor=1.0f, const float mollification_bias=0.0f, const float min_roughness=0.0f)

FERMAT_HOST_DEVICE	Bsdf (const TransportType transport, const RenderingContextView renderer, const cugar::Vector3f diffuse, const cugar::Vector3f specular, const float roughness, const cugar::Vector3f diffuse_trans, const float opacity=1.0f, const float ior=1.0f)

FERMAT_HOST_DEVICE const diffuse_trans_component &	diffuse_trans () const

FERMAT_HOST_DEVICE const diffuse_component &	diffuse () const

FERMAT_HOST_DEVICE const glossy_component &	glossy () const

FERMAT_HOST_DEVICE const glossy_component &	glossy_trans () const

FERMAT_HOST_DEVICE float	get_eta (const float NoV) const

FERMAT_HOST_DEVICE float	get_inv_eta (const float NoV) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE cugar::Vector3f	f (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o, const ComponentType components=kAllComponents) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	f (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o, cugar::Vector3f *f) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	f_and_p (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o, cugar::Vector3f f, float p, const cugar::SphericalMeasure measure=cugar::kProjectedSolidAngle, bool RR=true) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	f_and_p (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o, cugar::Vector3f &f, float &p, const cugar::SphericalMeasure measure=cugar::kProjectedSolidAngle, const bool RR=true, const ComponentType components=kAllComponents) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE float	p (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o, const cugar::SphericalMeasure measure=cugar::kProjectedSolidAngle, const bool RR=true, const ComponentType components=kAllComponents) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	sampling_weights (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f V, float &diffuse_refl_prob, float &diffuse_trans_prob, float &glossy_refl_prob, float &glossy_trans_prob) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	sampling_weights (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f V, float *w) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	normalize_sampling_weights (float *w_p, float &coat_reflection_prob, float &coat_transmission_prob, const bool RR, const ComponentType components=kAllComponents) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	fresnel_weights (const float VoH, const float eta, cugar::Vector3f &r_coeff, cugar::Vector3f &t_coeff) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	fresnel_weights (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f V, const cugar::Vector3f L, cugar::Vector3f &r_coeff, cugar::Vector3f &t_coeff) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	inner_component_weights (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f V, const cugar::Vector3f L, cugar::Vector3f &diffuse_refl_coeff, cugar::Vector3f &diffuse_trans_coeff, cugar::Vector3f &glossy_refl_coeff, cugar::Vector3f &glossy_trans_coeff) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	inner_component_weights (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f V, const cugar::Vector3f L, cugar::Vector3f *w) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	component_weights (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o, cugar::Vector3f &Fc_1, cugar::Vector3f &Tc_1, cugar::Vector3f &Fc_2, cugar::Vector3f &Tc_2, cugar::Vector3f *w) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void	component_weights (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o, cugar::Vector3f *w) const

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	sample_component (const cugar::DifferentialGeometry &geometry, const float z[3], const cugar::Vector3f in, const ComponentType out_comp, cugar::Vector3f &out, float &out_p, float &out_p_proj, cugar::Vector3f &out_g, const bool evaluate_full_bsdf=false) const

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool	sample (const cugar::DifferentialGeometry &geometry, const float z[3], const cugar::Vector3f in, ComponentType &out_comp, cugar::Vector3f &out, float &out_p, float &out_p_proj, cugar::Vector3f &out_g, bool RR=true, bool evaluate_full_bsdf=false, const ComponentType components=kAllComponents) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE bool	clearcoat_transmission (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, cugar::Vector3f &H, float &cos_theta_i, float &eta, cugar::Vector3f &Fc_1, cugar::Vector3f &Tc_1) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE float	compression_factor (const cugar::DifferentialGeometry &geometry, const cugar::Vector3f w_i, const cugar::Vector3f w_o) const

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE float	glossy_reflectance (const float cos_theta) const

Static Public Methods
static FERMAT_HOST_DEVICE uint32	component_count ()

static FERMAT_HOST_DEVICE uint32	component_index (const ComponentType comp)

static FERMAT_HOST_DEVICE ComponentType	component_mask (const ComponentIndex comp)

Public Members
diffuse_component	m_diffuse

diffuse_trans_component	m_diffuse_trans

glossy_component	m_glossy

glossy_component	m_glossy_trans

cugar::Vector3f	m_fresnel

cugar::Vector3f	m_reflectivity

float	m_ior

float	m_opacity

float	m_clearcoat_ior

const float *	m_glossy_reflectance

TransportType	m_transport

Member Enumeration Documentation

◆ ComponentIndex

enum Bsdf::ComponentIndex

component type indices

◆ ComponentType

enum Bsdf::ComponentType

component type bitmasks

Constructor & Destructor Documentation

◆ Bsdf() [1/4]

FERMAT_HOST_DEVICE Bsdf::Bsdf ( )

inline

constructor

◆ Bsdf() [2/4]

FERMAT_HOST_DEVICE Bsdf::Bsdf ( const Bsdf & bsdf )

inline

copy constructor

◆ Bsdf() [3/4]

FERMAT_HOST_DEVICE Bsdf::Bsdf	(	const TransportType	transport,
		const RenderingContextView	renderer,
		const MeshMaterial	material,
		const float	mollification_factor = `1.0f`,
		const float	mollification_bias = `0.0f`,
		const float	min_roughness = `0.0f`
	)

inline

constructor

◆ Bsdf() [4/4]

FERMAT_HOST_DEVICE Bsdf::Bsdf	(	const TransportType	transport,
		const RenderingContextView	renderer,
		const cugar::Vector3f	diffuse,
		const cugar::Vector3f	specular,
		const float	roughness,
		const cugar::Vector3f	diffuse_trans,
		const float	opacity = `1.0f`,
		const float	ior = `1.0f`
	)

inline

constructor

Member Function Documentation

◆ component_count()

static FERMAT_HOST_DEVICE uint32 Bsdf::component_count ( )

inlinestatic

return the number of components

◆ component_index()

static FERMAT_HOST_DEVICE uint32 Bsdf::component_index ( const ComponentType comp )

inlinestatic

return the 0-based index corresponding to a given component

◆ component_mask()

static FERMAT_HOST_DEVICE ComponentType Bsdf::component_mask ( const ComponentIndex comp )

inlinestatic

return the bitmask corresponding to a given component

◆ component_weights() [1/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::component_weights	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o,
		cugar::Vector3f &	Fc_1,
		cugar::Vector3f &	Tc_1,
		cugar::Vector3f &	Fc_2,
		cugar::Vector3f &	Tc_2,
		cugar::Vector3f *	w
	)		const

inline

evaluate the component weights of all layers - including the clearcoat

◆ component_weights() [2/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::component_weights	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o,
		cugar::Vector3f *	w
	)		const

inline

evaluate the component weights of all layers - including the clearcoat

◆ compression_factor()

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE float Bsdf::compression_factor	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o
	)		const

inline

apply the radiance compression factor of (eta_t / eta_i)^2

◆ diffuse()

FERMAT_HOST_DEVICE const diffuse_component& Bsdf::diffuse ( ) const

inline

return the diffuse reflection component

◆ diffuse_trans()

FERMAT_HOST_DEVICE const diffuse_trans_component& Bsdf::diffuse_trans ( ) const

inline

return the diffuse transmission component

◆ f() [1/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE cugar::Vector3f Bsdf::f	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o,
		const ComponentType	components = `kAllComponents`
	)		const

inline

evaluate the BSDF f(V,L)

Parameters

geometry	the local differential geometry
in	the incoming direction
out	the outgoing direction
components	the components to consider

◆ f() [2/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::f	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o,
		cugar::Vector3f *	f
	)		const

inline

evaluate the BSDF f(V,L) separately for all components

◆ f_and_p() [1/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::f_and_p	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o,
		cugar::Vector3f *	f,
		float *	p,
		const cugar::SphericalMeasure	measure = `cugar::kProjectedSolidAngle`,
		bool	RR = `true`
	)		const

inline

evaluate the BSDF f(V,L) and its pdf p(V,L) in a single call

◆ f_and_p() [2/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::f_and_p	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o,
		cugar::Vector3f &	f,
		float &	p,
		const cugar::SphericalMeasure	measure = `cugar::kProjectedSolidAngle`,
		const bool	RR = `true`,
		const ComponentType	components = `kAllComponents`
	)		const

inline

evaluate the BSDF f(V,L) and its p(V,L) in a single call

◆ fresnel_weights() [1/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::fresnel_weights	(	const float	VoH,
		const float	eta,
		cugar::Vector3f &	r_coeff,
		cugar::Vector3f &	t_coeff
	)		const

inline

compute the Fresnel reflection and transmission weights

◆ fresnel_weights() [2/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::fresnel_weights	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	V,
		const cugar::Vector3f	L,
		cugar::Vector3f &	r_coeff,
		cugar::Vector3f &	t_coeff
	)		const

inline

compute the Fresnel reflection and transmission weights

◆ get_eta()

FERMAT_HOST_DEVICE float Bsdf::get_eta ( const float NoV ) const

inline

return the incident ior ratio

◆ get_inv_eta()

FERMAT_HOST_DEVICE float Bsdf::get_inv_eta ( const float NoV ) const

inline

return the incident inverse ior ratio

◆ glossy()

FERMAT_HOST_DEVICE const glossy_component& Bsdf::glossy ( ) const

inline

return the glossy reflection component

◆ glossy_trans()

FERMAT_HOST_DEVICE const glossy_component& Bsdf::glossy_trans ( ) const

inline

return the glossy transmission component

◆ inner_component_weights() [1/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::inner_component_weights	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	V,
		const cugar::Vector3f	L,
		cugar::Vector3f &	diffuse_refl_coeff,
		cugar::Vector3f &	diffuse_trans_coeff,
		cugar::Vector3f &	glossy_refl_coeff,
		cugar::Vector3f &	glossy_trans_coeff
	)		const

inline

deprecated evaluate the Fresnel weight for the glossy component - after the clearcoat

◆ inner_component_weights() [2/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::inner_component_weights	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	V,
		const cugar::Vector3f	L,
		cugar::Vector3f *	w
	)		const

inline

evaluate the component weights of the inner layers - after the clearcoat

◆ normalize_sampling_weights()

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::normalize_sampling_weights	(	float *	w_p,
		float &	coat_reflection_prob,
		float &	coat_transmission_prob,
		const bool	RR,
		const ComponentType	components = `kAllComponents`
	)		const

inline

normalize the sampling weights of the inner layers given the coat sampling probability

◆ p()

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE float Bsdf::p	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	w_i,
		const cugar::Vector3f	w_o,
		const cugar::SphericalMeasure	measure = `cugar::kProjectedSolidAngle`,
		const bool	RR = `true`,
		const ComponentType	components = `kAllComponents`
	)		const

inline

evaluate the total projected probability p(V,L) = p(L|V)

Parameters

geometry	the local differential geometry
w_i	the incoming direction
w_o	the outgoing direction
measure	the spherical measure to use
RR	indicate whether to use Russian-Roulette or not

◆ sample()

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool Bsdf::sample	(	const cugar::DifferentialGeometry &	geometry,
		const float	z[3],
		const cugar::Vector3f	in,
		ComponentType &	out_comp,
		cugar::Vector3f &	out,
		float &	out_p,
		float &	out_p_proj,
		cugar::Vector3f &	out_g,
		bool	RR = `true`,
		bool	evaluate_full_bsdf = `false`,
		const ComponentType	components = `kAllComponents`
	)		const

inline

sample an outgoing direction

Parameters

geometry	the local differential geometry
z	the incoming direction
in	the incoming direction
out_comp	the output component
out	the outgoing direction
out_p	the output solid angle pdf
out_p_proj	the output projected solid angle pdf
out_g	the output sample value = f/p_proj
RR	indicate whether to use Russian-Roulette or not
evaluate_full_bsdf	ndicate whether to evaluate the full BSDF, or just an unbiased estimate
components	the components to consider

◆ sample_component()

FERMAT_HOST_DEVICE FERMAT_FORCEINLINE bool Bsdf::sample_component	(	const cugar::DifferentialGeometry &	geometry,
		const float	z[3],
		const cugar::Vector3f	in,
		const ComponentType	out_comp,
		cugar::Vector3f &	out,
		float &	out_p,
		float &	out_p_proj,
		cugar::Vector3f &	out_g,
		const bool	evaluate_full_bsdf = `false`
	)		const

inline

sample a given component

Parameters

geometry	the local differential geometry
z	the input random numbers, relative to the given component
in	the incoming direction
out_comp	the given component
out	the outgoing direction
out_p	the output solid angle pdf
out_p_proj	the output projected solid angle pdf
out_g	the output sample value = f/p_proj
RR	indicate whether to use Russian-Roulette or not
evaluate_full_bsdf	ndicate whether to evaluate the full BSDF, or just an unbiased estimate
components	the components to consider

◆ sampling_weights() [1/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::sampling_weights	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	V,
		float &	diffuse_refl_prob,
		float &	diffuse_trans_prob,
		float &	glossy_refl_prob,
		float &	glossy_trans_prob
	)		const

inline

evaluate the sampling weights for the inner layers

◆ sampling_weights() [2/2]

FERMAT_FORCEINLINE FERMAT_HOST_DEVICE void Bsdf::sampling_weights	(	const cugar::DifferentialGeometry &	geometry,
		const cugar::Vector3f	V,
		float *	w
	)		const

inline

evaluate the sampling weights for the inner layers

The documentation for this struct was generated from the following file:

C:/p4research/research/jpantaleoni/Fermat-Public/src/bsdf.h

Detailed description

Public Types

Public Methods

Static Public Methods

Public Members

Member Enumeration Documentation

◆ ComponentIndex

◆ ComponentType

Constructor & Destructor Documentation

◆ Bsdf() [1/4]

◆ Bsdf() [2/4]

◆ Bsdf() [3/4]

◆ Bsdf() [4/4]

Member Function Documentation

◆ component_count()

◆ component_index()

◆ component_mask()

◆ component_weights() [1/2]

◆ component_weights() [2/2]

◆ compression_factor()

◆ diffuse()

◆ diffuse_trans()

◆ f() [1/2]

◆ f() [2/2]

◆ f_and_p() [1/2]

◆ f_and_p() [2/2]

◆ fresnel_weights() [1/2]

◆ fresnel_weights() [2/2]

◆ get_eta()

◆ get_inv_eta()

◆ glossy()

◆ glossy_trans()

◆ inner_component_weights() [1/2]

◆ inner_component_weights() [2/2]

◆ normalize_sampling_weights()

◆ p()

◆ sample()

◆ sample_component()

◆ sampling_weights() [1/2]

◆ sampling_weights() [2/2]