Abstract BSDF base-class. More...

#include <mitsuba/render/bsdf.h>

Inheritance diagram for mitsuba::BSDF:

Public Types
enum	EBSDFType { ENull = 0x00001, EDiffuseReflection = 0x00002, EDiffuseTransmission = 0x00004, EGlossyReflection = 0x00008, EGlossyTransmission = 0x00010, EDeltaReflection = 0x00020, EDeltaTransmission = 0x00040, EDelta1DReflection = 0x00080, EDelta1DTransmission = 0x00100, EAnisotropic = 0x01000, ESpatiallyVarying = 0x02000, ENonSymmetric = 0x04000, EFrontSide = 0x08000, EBackSide = 0x10000, EUsesSampler = 0x20000 }
	This list of flags is used to classify the different types of lobes that are implemented in a BSDF instance. More...

enum	ETypeCombinations { EReflection, ETransmission, EDiffuse = EDiffuseReflection \| EDiffuseTransmission, EGlossy = EGlossyReflection \| EGlossyTransmission, ESmooth = EDiffuse \| EGlossy, EDelta = ENull \| EDeltaReflection \| EDeltaTransmission, EDelta1D = EDelta1DReflection \| EDelta1DTransmission, EAll = EDiffuse \| EGlossy \| EDelta \| EDelta1D }
	Convenient combinations of flags from EBSDFType. More...

Public Member Functions
int	getComponentCount () const
	Return the number of components of this BSDF. More...

unsigned int	getType () const
	Return a listing of this BSDF's component types and properties, combined using binary OR. More...

unsigned int	getType (int component) const

bool	hasComponent (unsigned int type) const
	Test whether this BSDF contains a certain type of component. More...

bool	usesRayDifferentials () const
	Return whether this BSDF makes use of ray differentials. More...

virtual Spectrum	getDiffuseReflectance (const Intersection &its) const
	Return the diffuse reflectance value (if any) More...

virtual Spectrum	getSpecularReflectance (const Intersection &its) const
	Return the specular reflectance value (if any) More...

virtual Spectrum	sample (BSDFSamplingRecord &bRec, const Point2 &sample) const =0
	Sample the BSDF and return the importance weight (i.e. the value of the BSDF divided by the probability density of the sample). More...

virtual Spectrum	sample (BSDFSamplingRecord &bRec, Float &pdf, const Point2 &sample) const =0
	Sample the BSDF and return the probability density and the importance weight of the sample (i.e. the value of the BSDF divided by the probability density) More...

virtual Spectrum	eval (const BSDFSamplingRecord &bRec, EMeasure measure=ESolidAngle) const =0
	Evaluate the BSDF f(wi, wo) or its adjoint version f^{*}(wi, wo) More...

virtual Float	pdf (const BSDFSamplingRecord &bRec, EMeasure measure=ESolidAngle) const =0
	Compute the probability of sampling `bRec.wo` (given `bRec.wi`). More...

virtual Float	getEta () const
	For transmissive BSDFs: return the material's relative index of refraction. More...

virtual Float	getRoughness (const Intersection &its, int index) const
	For rough BSDFs: return the root mean square surface roughness of the given BSDF component. More...

virtual Frame	getFrame (const Intersection &its) const
	Sometimes, BSDF models make use of a perturbed frame for internal shading computations (e.g. bump maps). This function exposes this internal frame. More...

virtual void	getFrameDerivative (const Intersection &its, Frame &du, Frame &dv) const
	Sometimes, BSDF models make use of a perturbed frame for internal shading computations (e.g. bump maps). This function computes the derivative of this frame with respect to the UV parameterization of the underlying shape. More...

virtual const Class *	getClass () const
	Retrieve this object's class. More...

ConfigurableObject interface
virtual void	configure ()
	Configure the material (called after construction by the XML parser) More...

virtual void	addChild (const std::string &string, ConfigurableObject *obj)
	Add a child object. More...

void	addChild (ConfigurableObject *child)
	Add an unnamed child. More...

virtual void	serialize (Stream stream, InstanceManager manager) const
	Serialize this object to a stream. More...

virtual void	setParent (ConfigurableObject *parent)
	Set the parent object. More...

Public Member Functions inherited from mitsuba::ConfigurableObject
void	addChild (ConfigurableObject *child)
	Add an unnamed child. More...

const std::string &	getID () const
	Return the identifier associated with this instance (or "unnamed") More...

void	setID (const std::string &name)
	Set the identifier associated with this instance. More...

const Properties &	getProperties () const
	Return the properties object that was originally used to create this instance. More...

Public Member Functions inherited from mitsuba::SerializableObject
	SerializableObject (Stream stream, InstanceManager manager)
	Unserialize a serializable object. More...

Public Member Functions inherited from Object
	Object ()
	Construct a new object. More...

int	getRefCount () const
	Return the current reference count. More...

void	incRef () const
	Increase the reference count of the object by one. More...

void	decRef (bool autoDeallocate=true) const
	Decrease the reference count of the object and possibly deallocate it. More...

virtual std::string	toString () const
	Return a human-readable string representation of the object's contents. More...

Public Member Functions inherited from mitsuba::HWResource
virtual Shader *	createShader (Renderer *renderer) const

virtual	~HWResource ()

Static Public Member Functions
static EMeasure	getMeasure (unsigned int componentType)
	Return the measure corresponding to a particular component type. More...

Static Public Member Functions inherited from Object
static void	staticInitialization ()
	Initializes the built-in reference count debugger (if enabled) More...

static void	staticShutdown ()
	Free the memory taken by staticInitialization() More...

Static Public Attributes
static Class *	m_theClass

Static Public Attributes inherited from mitsuba::ConfigurableObject
static Class *	m_theClass

Static Public Attributes inherited from mitsuba::SerializableObject
static Class *	m_theClass

Static Public Attributes inherited from Object
static Class *	m_theClass
	Pointer to the object's class descriptor. More...

Protected Member Functions
	BSDF (const Properties &props)
	Create a new BSDF instance. More...

	BSDF (Stream stream, InstanceManager manager)
	Unserialize a BSDF instance. More...

Texture *	ensureEnergyConservation (Texture *tex, const std::string &paramName, Float max) const
	Convenience function to ensure energy conservation. More...

std::pair< Texture , Texture >	ensureEnergyConservation (Texture tex1, Texture tex2, const std::string &paramName1, const std::string &paramName2, Float max) const
	Convenience function to ensure energy conservation. More...

virtual	~BSDF ()
	Virtual destructor. More...

Protected Member Functions inherited from mitsuba::ConfigurableObject
virtual	~ConfigurableObject ()
	Virtual destructor. More...

	ConfigurableObject (const Properties &props)
	Construct a configurable object. More...

	ConfigurableObject (Stream stream, InstanceManager manager)
	Unserialize a configurable object. More...

Protected Member Functions inherited from mitsuba::SerializableObject
	SerializableObject ()
	Construct a serializable object. More...

virtual	~SerializableObject ()
	Virtual deconstructor. More...

Protected Member Functions inherited from Object
virtual	~Object ()
	Virtual private deconstructor. (Will only be called by ref) More...

Protected Attributes
std::vector< unsigned int >	m_components

unsigned int	m_combinedType

bool	m_usesRayDifferentials

bool	m_ensureEnergyConservation

Protected Attributes inherited from mitsuba::ConfigurableObject
Properties	m_properties

Detailed Description

Abstract BSDF base-class.

This class implements an abstract interface to all BSDF plugins in Mitsuba. It exposes functions for evaluating and sampling the model, and it allows querying the probability density of the sampling method. Smooth two-dimensional density functions, as well as degenerate one-dimensional and discrete densities are all handled within the same framework.

For improved flexibility with respect to the various rendering algorithms, this class can sample and evaluate a complete BSDF, but it also allows to pick and choose individual components of multi-lobed BSDFs based on their properties and component indices. This selection is specified using a special record that is provided along with every query.

BSDFSamplingRecord.

Member Enumeration Documentation

enum mitsuba::BSDF::EBSDFType

This list of flags is used to classify the different types of lobes that are implemented in a BSDF instance.

They are also useful for picking out individual components by setting combinations in BSDFSamplingRecord::typeMask.

Enumerator
ENull	'null' scattering event, i.e. particles do not undergo deflection
EDiffuseReflection	Ideally diffuse reflection.
EDiffuseTransmission	Ideally diffuse transmission.
EGlossyReflection	Glossy reflection.
EGlossyTransmission	Glossy transmission.
EDeltaReflection	Reflection into a discrete set of directions.
EDeltaTransmission	Transmission into a discrete set of directions.
EDelta1DReflection	Reflection into a 1D space of directions.
EDelta1DTransmission	Transmission into a 1D space of directions.
EAnisotropic	Other lobe attributes. The lobe is not invariant to rotation around the normal
ESpatiallyVarying	The BSDF depends on the UV coordinates.
ENonSymmetric	Flags non-symmetry (e.g. transmission in dielectric materials)
EFrontSide	Supports interactions on the front-facing side.
EBackSide	Supports interactions on the back-facing side.
EUsesSampler	Uses extra random numbers from the supplied sampler instance.

enum mitsuba::BSDF::ETypeCombinations

Convenient combinations of flags from EBSDFType.

Enumerator
EReflection	Any reflection component (scattering into discrete, 1D, or 2D set of directions)
ETransmission	Any transmission component (scattering into discrete, 1D, or 2D set of directions)
EDiffuse	Diffuse scattering into a 2D set of directions.
EGlossy	Non-diffuse scattering into a 2D set of directions.
ESmooth	Scattering into a 2D set of directions.
EDelta	Scattering into a discrete set of directions.
EDelta1D	Scattering into a 1D space of directions.
EAll	Any kind of scattering.

Constructor & Destructor Documentation

mitsuba::BSDF::BSDF ( const Properties & props )

protected

Create a new BSDF instance.

mitsuba::BSDF::BSDF	(	Stream *	stream,
		InstanceManager *	manager
	)

protected

Unserialize a BSDF instance.

virtual mitsuba::BSDF::~BSDF ( )

protectedvirtual

Virtual destructor.

Member Function Documentation

virtual void mitsuba::BSDF::addChild	(	const std::string &	string,
		ConfigurableObject *	obj
	)

virtual

Add a child object.

Reimplemented from mitsuba::ConfigurableObject.

void mitsuba::BSDF::addChild ( ConfigurableObject * child )

inline

Add an unnamed child.

virtual void mitsuba::BSDF::configure ( )

virtual

Configure the material (called after construction by the XML parser)

Reimplemented from mitsuba::ConfigurableObject.

Texture* mitsuba::BSDF::ensureEnergyConservation	(	Texture *	tex,
		const std::string &	paramName,
		Float	max
	)		const

protected

Convenience function to ensure energy conservation.

This function determines the component-wise maximum of the texture tex and checks if it is below max. If yes, it returns the texture unmodified. Otherwise, it wraps the texture into a ScaleTexture instance (with a scaling factor chosen so that the desired maximum max is abided) and prints a warning.

std::pair<Texture , Texture > mitsuba::BSDF::ensureEnergyConservation	(	Texture *	tex1,
		Texture *	tex2,
		const std::string &	paramName1,
		const std::string &	paramName2,
		Float	max
	)		const

protected

Convenience function to ensure energy conservation.

This function determines the component-wise maximum of the sum tex1 + tex2 and checks if it is below max. If yes, it returns the texture unmodified. Otherwise, it wraps each the texture into a ScaleTexture instance (with a scaling factor chosen so that the desired maximum max is abided) and prints a warning.

virtual Spectrum mitsuba::BSDF::eval	(	const BSDFSamplingRecord &	bRec,
		EMeasure	measure = `ESolidAngle`
	)		const

pure virtual

Evaluate the BSDF f(wi, wo) or its adjoint version f^{*}(wi, wo)

This method allows to query the BSDF as a whole or pick out individual components. When querying a smooth (i.e. non-degenerate) component, it already multiplies the result by the cosine foreshortening factor with respect to the outgoing direction.

Parameters

bRec	A record with detailed information on the BSDF query
measure	Specifies the measure of the component. This is necessary to handle BSDFs, whose components live on spaces with different measures. (E.g. a diffuse material with an ideally smooth dielectric coating).

virtual const Class* mitsuba::BSDF::getClass ( ) const

virtual

Retrieve this object's class.

Reimplemented from mitsuba::ConfigurableObject.

int mitsuba::BSDF::getComponentCount ( ) const

inline

Return the number of components of this BSDF.

virtual Spectrum mitsuba::BSDF::getDiffuseReflectance ( const Intersection & its ) const

virtual

Return the diffuse reflectance value (if any)

virtual Float mitsuba::BSDF::getEta ( ) const

virtual

For transmissive BSDFs: return the material's relative index of refraction.

The default implementation returns 1.0.

Returns: interior IOR / exteriorIOR

virtual Frame mitsuba::BSDF::getFrame ( const Intersection & its ) const

virtual

Sometimes, BSDF models make use of a perturbed frame for internal shading computations (e.g. bump maps). This function exposes this internal frame.

By default, it returns its.shFrame

virtual void mitsuba::BSDF::getFrameDerivative	(	const Intersection &	its,
		Frame &	du,
		Frame &	dv
	)		const

virtual

Sometimes, BSDF models make use of a perturbed frame for internal shading computations (e.g. bump maps). This function computes the derivative of this frame with respect to the UV parameterization of the underlying shape.

static EMeasure mitsuba::BSDF::getMeasure ( unsigned int componentType )

inlinestatic

Return the measure corresponding to a particular component type.

virtual Float mitsuba::BSDF::getRoughness	(	const Intersection &	its,
		int	index
	)		const

virtual

For rough BSDFs: return the root mean square surface roughness of the given BSDF component.

An infinite value indicates a component that is ideally diffuse

virtual Spectrum mitsuba::BSDF::getSpecularReflectance ( const Intersection & its ) const

inlinevirtual

Return the specular reflectance value (if any)

unsigned int mitsuba::BSDF::getType ( ) const

inline

Return a listing of this BSDF's component types and properties, combined using binary OR.

See Also: EBSDFType

unsigned int mitsuba::BSDF::getType ( int component ) const

inline

Returns the classification flags of a specific component

See Also: EBSDFType

bool mitsuba::BSDF::hasComponent ( unsigned int type ) const

inline

Test whether this BSDF contains a certain type of component.

virtual Float mitsuba::BSDF::pdf	(	const BSDFSamplingRecord &	bRec,
		EMeasure	measure = `ESolidAngle`
	)		const

pure virtual

Compute the probability of sampling bRec.wo (given bRec.wi).

This method provides access to the probability density that would result when supplying the same BSDF query record to the sample() method. It correctly handles changes in probability when only a subset of the components is chosen for sampling (this can be done using the BSDFSamplingRecord::component and BSDFSamplingRecord::typeMask fields).

Parameters

bRec	A record with detailed information on the BSDF query
measure	Specifies the measure of the component. This is necessary to handle BSDFs, whose components live on spaces with different measures. (E.g. a diffuse material with an ideally smooth dielectric coating).

virtual Spectrum mitsuba::BSDF::sample	(	BSDFSamplingRecord &	bRec,
		const Point2 &	sample
	)		const

pure virtual

Sample the BSDF and return the importance weight (i.e. the value of the BSDF divided by the probability density of the sample).

When the probability density is not explicitly required, this function should be preferred, since it is potentially faster by making use of cancellations during the division.

If a component mask or a specific component index is specified, the sample is drawn from the matching component, if it exists. Depending on the provided transport type, either the BSDF or its adjoint version is used.

Parameters

bRec	A BSDF query record
sample	A uniformly distributed sample on \([0,1]^2\)

Returns: The BSDF value divided by the probability density of the sample sample (multiplied by the cosine foreshortening factor when a non-delta component is sampled) A zero spectrum means that sampling failed.

Remarks: This function is not exposed by the Python API. See the other sample function instead.

virtual Spectrum mitsuba::BSDF::sample	(	BSDFSamplingRecord &	bRec,
		Float &	pdf,
		const Point2 &	sample
	)		const

pure virtual

Sample the BSDF and return the probability density and the importance weight of the sample (i.e. the value of the BSDF divided by the probability density)

If a component mask or a specific component index is specified, the sample is drawn from the matching component, if it exists. Depending on the provided transport type, either the BSDF or its adjoint version is used.

When sampling a continuous/non-delta component, this method also multiplies by the cosine foreshorening factor with respect to the sampled direction.

Parameters

bRec	A BSDF query record
sample	A uniformly distributed sample on \([0,1]^2\)
pdf	Will record the probability with respect to solid angles (or the discrete probability when a delta component is sampled)

Returns: The BSDF value (multiplied by the cosine foreshortening factor when a non-delta component is sampled). A zero spectrum means that sampling failed.

Remarks: From Python, this function is is called using the syntax value, pdf = bsdf.sample(bRec, sample)

virtual void mitsuba::BSDF::serialize	(	Stream *	stream,
		InstanceManager *	manager
	)		const

virtual

Serialize this object to a stream.

Reimplemented from mitsuba::ConfigurableObject.

virtual void mitsuba::BSDF::setParent ( ConfigurableObject * parent )

virtual

Set the parent object.

Reimplemented from mitsuba::ConfigurableObject.

bool mitsuba::BSDF::usesRayDifferentials ( ) const

inline

Return whether this BSDF makes use of ray differentials.

Member Data Documentation

unsigned int mitsuba::BSDF::m_combinedType

protected

std::vector<unsigned int> mitsuba::BSDF::m_components

protected

bool mitsuba::BSDF::m_ensureEnergyConservation

protected

Class* mitsuba::BSDF::m_theClass

static

bool mitsuba::BSDF::m_usesRayDifferentials

protected

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

include/mitsuba/render/bsdf.h

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation