PhongBRDF Class Reference

#include <PhongBRDF.h>

Inheritance diagram for PhongBRDF:


Public Types
enum	RetVal { NONZERO_CONTRIB = 1, BAD_PARAMS = 2, NL_NEGATIVE = 3, NV_NEGATIVE = 4, NL_OR_NV_NEGATIVE = 5, ZERO_CONTRIB = 6 }
Public Member Functions
	PhongBRDF (void)
virtual RetVal	reflectance (const MatVisitor &visitor, const Vector3 L, const Vector3 V, const Vector3 *N, Vector3 &color)
virtual RetVal	reflectanceVNL (const MatVisitor &visitor, const Vector3 L, const Vector3 V, const Vector3 *N, double NV, double NL, Vector3 &color)
virtual RetVal	reflectanceNL (const MatVisitor &visitor, const Vector3 L, const Vector3 V, const Vector3 *N, double NL, Vector3 &color)
virtual BRDF *	clone (void) const
virtual double	albedo (const MatVisitor &visitor, const Vector3 &N, const Vector3 *V) const
virtual void	importanceSample (const MatVisitor &visitor, const Vector3 &D, double r1, double r2, Vector3 &dir, double *pPDFVal)
virtual Vector2	dir2uv (const MatVisitor &visitor, const Vector3 &N, const Vector3 &D) const
	_isIsotropic (isotropic)
bool	diffuse (void) const
bool	specular (void) const
bool	isotropic (void) const
bool	anisotropic (void) const
Public Attributes
	__pad0__: _isDiffuse(diffuse)
Protected Member Functions
virtual void	_duplicate_attributes (const BRDF &src)
Protected Attributes
bool	_isDiffuse
bool	_isIsotropic

Detailed Description

Phong's specular BRDF (without diffuse and ambient components).

This BRDF doesn not conserve energy because (L*N) can become arbitrarily small.
The Helmholtz reciprocity is violated because the equation is not synmetric in L and V.

$BRDF = k_s \frac{\cos^r{\alpha}}{\cos{\theta}} = k_s \frac{(R*V)^r}{(L*N)}$

Definition at line 24 of file PhongBRDF.h.

Member Enumeration Documentation

enum RetVal [inherited]

Informations about reflectance
Enumerator:

NONZERO_CONTRIB color is set (including black)

BAD_PARAMS unable to compute reflectance

NL_NEGATIVE dot-product of normal, N, and light direction, L, is less than zero

NV_NEGATIVE dot-product of normal, N, and viewer direction, V, is less than zero

NL_OR_NV_NEGATIVE either N*L or N*V is less than zero

ZERO_CONTRIB no energy is reflected in given direction

Definition at line 22 of file BRDF.h.

Constructor & Destructor Documentation

PhongBRDF ( void ) [inline]

Constructor
Definition at line 34 of file PhongBRDF.h.

Member Function Documentation

virtual void _duplicate_attributes ( const BRDF & src ) [inline, protected, virtual]

Reimplemented from SpecularBRDF.
Definition at line 26 of file PhongBRDF.h.
References SpecularBRDF::_duplicate_attributes().

_isIsotropic ( isotropic ) [inline, inherited]

Definition at line 51 of file BRDF.h.

virtual double albedo ( const MatVisitor & visitor,

const Vector3 & N,

const Vector3 * V

) const [inline, virtual]

Albedo for importance sampling strategies.

Parameters:

visitor visitor of material coefficients

N normalized normal vector

V normalized direction to viewer

Returns:
$albedo = 2 \pi \frac{avg(k_s)}{(r+2) \cos{\theta}}$ , where $avg()$ is average of specular material components and $r$ is roughness.

Implements SpecularBRDF.
Definition at line 108 of file PhongBRDF.h.
References MatVisitor::avgSpecular(), MatVisitor::intRoughness(), and PI.
Referenced by CookTorranceBRDF::albedo(), and BlinnBRDF::albedo().

bool anisotropic ( void ) const [inline, inherited]

Returns:
true if BRDF is anisotropic (reflectance dependents on rotation around normal), false otherwise

Definition at line 80 of file BRDF.h.

virtual BRDF* clone ( void ) const [inline, virtual]

Duplicates the BRDF
Implements SpecularBRDF.
Definition at line 96 of file PhongBRDF.h.

bool diffuse ( void ) const [inline, inherited]

Returns:
true if BRDF is diffuse, false otherwise

Definition at line 61 of file BRDF.h.

virtual Vector2 dir2uv ( const MatVisitor & visitor,

const Vector3 & N,

const Vector3 & D

) const [inline, virtual]

Gets direction in global coords and returns its generating "random" numbers (i.e. the inverse function to importanceSample()).

Parameters:

visitor not used

N normalized normal vector

D normalized direction

Returns:
"random" numbers generating direction D; x item of returned vector corresponds to r1 of importanceSample() method, y item corresponds to r2; $(u,v) = (\sin^{r+1}\theta, \frac{\phi}{2 \pi})$

Implements SpecularBRDF.
Definition at line 157 of file PhongBRDF.h.
References Hemisphere::dir2uvPriorToPoweredZenith(), and MatVisitor::intRoughness().
Referenced by BlinnBRDF::dir2uv().

virtual void importanceSample ( const MatVisitor & visitor,

const Vector3 & D,

double r1,

double r2,

Vector3 & dir,

double * pPDFVal

) [inline, virtual]

Point sampling interface - importance sampling. This method gets two random numbers and preffered direction of random sample and selects amd returns random direction.
$(\theta, \phi) = (\arcsin({(1-r_1)^{\frac{1}{r+1}}}), 2 \pi r_2)$ where $r$ is roughness

Parameters:

visitor visitor of material coefficients

D normalized vector determining prefered direction of the sample

r1 random number from the range [0,1)

r2 random number from the range [0,1)

dir random direction selected by this method ( $(\theta,\phi)$ transformed to the world coodinates)

pPDFVal corresponding PDF value, $PDF = (r+1) \frac{\cos^r{\theta}}{2 \pi}$

Implements SpecularBRDF.
Definition at line 133 of file PhongBRDF.h.
References MatVisitor::intRoughness(), and Hemisphere::samplePriorToPoweredZenith().
Referenced by CookTorranceBRDF::importanceSample(), and BlinnBRDF::importanceSample().

bool isotropic ( void ) const [inline, inherited]

Returns:
true if BRDF is isotropic (reflectance is independent of rotation around normal), false otherwise

Definition at line 73 of file BRDF.h.

virtual RetVal reflectance ( const MatVisitor & visitor,

const Vector3 * L,

const Vector3 * V,

const Vector3 * N,

Vector3 & color

) [inline, virtual]

Computes and returns actual reflectance.

Parameters:

visitor visitor of material coefficients

L normalized direction to light source

V normalized direction to viewer

N normalized normal vector

color computed reflected energy (color)

Returns:
additionnal informations about reflected energy

Implements SpecularBRDF.
Definition at line 36 of file PhongBRDF.h.
References MatVisitor::intRoughness(), and MatVisitor::specular().

virtual RetVal reflectanceNL ( const MatVisitor & visitor,

const Vector3 * L,

const Vector3 * V,

const Vector3 * N,

double NL,

Vector3 & color

) [inline, virtual]

Computes and returns actual reflectance. This variant speeds up the computation using given precomputed dot-product of N and L

Parameters:

visitor visitor of material coefficients

L normalized direction to light source

V normalized direction to viewer

N normalized normal vector

NL precomputed dot-product of normal N and L

color computed reflected energy (color)

Returns:
additionnal informations about reflected energy

Implements SpecularBRDF.
Definition at line 77 of file PhongBRDF.h.
References MatVisitor::intRoughness(), and MatVisitor::specular().

virtual RetVal reflectanceVNL ( const MatVisitor & visitor,

const Vector3 * L,

const Vector3 * V,

const Vector3 * N,

double NV,

double NL,

Vector3 & color

) [inline, virtual]

Computes and returns actual reflectance. This variant speeds up the computation using given precomputed dot-products of N, V and L

Parameters:

visitor visitor of material coefficients

L normalized direction to light source

V normalized direction to viewer

N normalized normal vector

NV precomputed dot-product of normal N and V

NL precomputed dot-product of normal N and L

color computed reflected energy (color)

Returns:
additionnal informations about reflected energy

Implements SpecularBRDF.
Definition at line 57 of file PhongBRDF.h.
References MatVisitor::intRoughness(), and MatVisitor::specular().

bool specular ( void ) const [inline, inherited]

Returns:
true if BRDF is specular, false otherwise

Definition at line 66 of file BRDF.h.

Member Data Documentation

__pad0__ [inherited]

Contructor

Parameters:

diffuse determines whether this BRDF is diffuse (reflectance is independent of viewer direction)

isotropic determines whether this BRDF is isotropic (reflectance is independent of rotation around normal)

Definition at line 51 of file BRDF.h.

bool _isDiffuse [protected, inherited]

Definition at line 32 of file BRDF.h.
Referenced by BRDF::_duplicate_attributes().

bool _isIsotropic [protected, inherited]

Definition at line 33 of file BRDF.h.
Referenced by BRDF::_duplicate_attributes().

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

esg/include/esg/brdf/PhongBRDF.h

Generated on Wed Jun 28 12:24:33 2006 for esg by

1.4.6

PhongBRDF Class Reference

Public Types

Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation