/**
* Compute the diffusely reemited light data and place the result into reemited.
* localBasis : the object localBasis at the computation point.
* surfaceCoordinate : the surface coordinate (texture coordinate) of the computation
* point on the object.
* incident : the incident ray (light ray)
* view : the view ray (from the camera or bounced)
* incidentLight : the incident light comming from the incident ray.
* reemitedLight : the light reemited into the view direction (result will be placed
* here).
*/
void RoughLambertianBRDF::getDiffuseReemited(const Basis& localBasis, const Point2D& surfaceCoordinate, const LightVector& incidentLight, LightVector& reemitedLight)
{
Vector view = reemitedLight.getRay().v;
Vector incident = incidentLight.getRay().v;
Real cosOi = -incident.dot(localBasis.k);
Real cosOv = -view.dot(localBasis.k);
if(cosOi <= 0)
{
reemitedLight.clear();
return;
}
if(cosOi>=1.0)
cosOi=1.0;
if(cosOv>=1.0)
cosOv=1.0;
Real Oi = std::acos(cosOi);
Real Ov = std::acos(cosOv);
Real Pi = std::atan2(incident.dot(localBasis.j), incident.dot(localBasis.i));
Real Pv = std::atan2(view.dot(localBasis.j), view.dot(localBasis.i));
Real factor = OrenNayarFormula::orenNayarReflectance(Oi, Pi, Ov, Pv, _roughness);
for(unsigned int i=0; i<reemitedLight.size(); i++)
reemitedLight[i].setRadiance(incidentLight[i].getRadiance()*_spectrum[incidentLight[i].getIndex()]*factor);
reemitedLight.changeReemitedPolarisationFramework(localBasis.k);
}
/**
* Compute the secondary rays for diffuse reflexion and place them into the subrays
* vector.
* localBasis : the local base on the object at the computation point.
* surfaceCoordinate : the surface coordinate (texture coordinate) of the computation
* point on the object.
* view : the view ray (from the camera or bounced)
* nbRays : the number of wanted ray. It is an indicative information.
* subrays : the vector were the secondaries rays will be put.
* weights : the weights corresponding to the distribution
*/
void RoughLambertianBRDF::getRandomDiffuseRay(const Basis& localBasis, const Point2D& surfaceCoordinate, LightVector& reemitedLight, unsigned int nbRays, std::vector<LightVector>& subrays)
{
Vector normal=localBasis.k;
if(normal.dot(reemitedLight.getRay().v)>0)
normal.mul(-1);
for(unsigned int i=0; i<nbRays; i++)
{
Vector incident;
Real norm2;
Real cosOi;
do{
incident[0]=rand()*2.0/RAND_MAX - 1.0;
incident[1]=rand()*2.0/RAND_MAX - 1.0;
incident[2]=rand()*2.0/RAND_MAX - 1.0;
norm2=incident.square();
incident.normalize();
cosOi=incident.dot(normal);
}while(norm2>cosOi*cosOi || cosOi<=0.0);
LightVector subray;
subray.setRay(localBasis.o, incident);
subray.changeReemitedPolarisationFramework(normal);
subray.initSpectralData(reemitedLight);
subray.setWeight(1.0/M_PI);
subrays.push_back(subray);
}
}
/**
* Compute the diffusely reemited light data and place the result into reemited.
* localBasis : the object localBasis at the computation point.
* surfaceCoordinate : the surface coordinate (texture coordinate) of the computation
* point on the object.
* incident : the incident ray (light ray)
* view : the view ray (from the camera or bounced)
* incidentLight : the incident light comming from the incident ray.
* reemitedLight : the light reemited into the view direction (result will be placed
* here).
*/
void BeckmannBRDF::getDiffuseReemited(const Basis& localBasis, const Point2D& surfaceCoordinate, const LightVector& incidentLight, LightVector& reemitedLight)
{
const Vector& incident = incidentLight.getRay().v;
const Vector& view = reemitedLight.getRay().v;
//Computing the micro normal
Vector microNormal;
microNormal.setsum(incident, view);
microNormal.mul(-1.0);
microNormal.normalize();
//Computing some cosinuses and sinuses
Real cosLN = -localBasis.k.dot(incident); // incident and normal
Real cosVN = -localBasis.k.dot(view); // view and normal
Real cosHN = localBasis.k.dot(microNormal); // micro normal and normal
Real cosLH = -microNormal.dot(incident); // incident and micro normal
Real cosVH = -microNormal.dot(view); // view and micro normal
//Compute Beckmann and Shadowing&masking coeficients
Real beckmann = BeckmannRoughnessFormula::BeckmannDistribution(cosHN,
_roughness);
Real shadmask = BeckmannRoughnessFormula::BeckmannShadowMasking(cosLN,
cosVN,
cosVH,
cosHN);
//Setting the polarisation framework
LightVector localIncidentLight(incidentLight);
localIncidentLight.changeIncidentPolarisationFramework(microNormal);
localIncidentLight.flip();
reemitedLight.changeReemitedPolarisationFramework(microNormal);
if(cosVN <=0.001 || cosLN <=0.001)
{
reemitedLight.clear();
return;
}
//Computing reflectances for each wavelength
for(unsigned int i=0; i<localIncidentLight.size(); i++)
{
Real ROrth, RPara;
getReflectance(cosLH, localIncidentLight[i].getIndex(), ROrth, RPara);
reemitedLight[i].applyReflectance(localIncidentLight[i], RPara*beckmann*shadmask, ROrth*beckmann*shadmask);
}
}
void BeckmannBRDF::getDiffuseReemitedFromAmbiant(const Basis& localBasis, const Point2D& surfaceCoordinate, LightVector& reemitedLight, const Spectrum& incident)
{
const Vector& light = localBasis.k;
const Vector& view = reemitedLight.getRay().v;
//Computing the micro normal
Vector microNormal;
microNormal.setsum(light, view);
microNormal.mul(-1.0);
microNormal.normalize();
//Computing some cosinuses and sinuses
Real cosLN = -localBasis.k.dot(light); // light and normal
Real cosVN = -localBasis.k.dot(view); // view and normal
Real cosHN = localBasis.k.dot(microNormal); // micro normal and normal
Real cosLH = -microNormal.dot(light); // light and micro normal
Real cosVH = -microNormal.dot(view); // view and micro normal
//Compute Beckmann and Shadowing&masking coeficients
Real beckmann = BeckmannRoughnessFormula::BeckmannDistribution(cosHN,
_roughness);
Real shadmask = BeckmannRoughnessFormula::BeckmannShadowMasking(cosLN,
cosVN,
cosVH,
cosHN);
if(cosVN <=0.001 )
{
reemitedLight.clear();
return;
}
for(unsigned int wl=0; wl < reemitedLight.size(); wl++) {
Real ROrth, RPara;
getReflectance(cosLH, wl, ROrth, RPara);
ROrth *= beckmann * shadmask;
RPara *= beckmann * shadmask;
reemitedLight[wl].setRadiance(incident[wl] /** cosVN*/ * 0.5 * (ROrth + RPara));
}
reemitedLight.changeReemitedPolarisationFramework(microNormal);
}
/**
* Compute the secondary rays for diffuse reflexion and place them into the subrays
* vector.
* localBasis : the local base on the object at the computation point.
* surfaceCoordinate : the surface coordinate (texture coordinate) of the computation
* point on the object.
* view : the view ray (from the camera or bounced)
* nbRays : the number of wanted ray. It is an indicative information.
* subrays : the vector were the secondaries rays will be put.
* weights : the weights corresponding to the distribution
*/
void BeckmannBRDF::getRandomDiffuseRay(const Basis& localBasis, const Point2D& surfaceCoordinate, LightVector& reemitedLight, unsigned int nbRays, std::vector<LightVector>& subrays)
{
Vector view = reemitedLight.getRay().v;
view.mul(-1.0);
if(view.dot(localBasis.k)<0)
return;
for(unsigned int i=0; i<nbRays; i++)
{
Vector dir;
Real weight;
BeckmannRoughnessFormula::getBeckmannRandomRay(localBasis, view, _roughness, weight, dir);
LightVector subray;
subray.setRay(localBasis.o, dir);
subray.initSpectralData(reemitedLight);
subray.changeReemitedPolarisationFramework(localBasis.k);
subray.setWeight(weight);
subrays.push_back(subray);
}
}