// only light sampling..
// left only for reference
inline void EstimateDirectIllumination (
const Scene * thisScene,
const Intersection * intersectionInfo,
const Ray & ray,
double & light_pdf,
Spectrum & lightSourceSamplingContribution
)
{
Objects * obj = intersectionInfo->object;
BRDFModels * brdf = obj->brdf_model;
Vector newRayDirection;
Vector normalDirection;
normalDirection = intersectionInfo->normal;
Attenuation attenuationFactor;
bool delta_brdf_hitEmissive = false;
bool occludedByObjects = true;
Spectrum lightIntensity;
light_pdf = 0; // to be added
if ( brdf->surfaceFlag == surface_delta )
{
return;
}
// Spectrum lightSourceSamplingContribution;
// Spectrum brdfSamplingContribution;
// light source sampling evaluation
Objects * light;
light = thisScene->AquireOneOfEmissiveObjects();
Pnt3D pointOnLight;
int i = 0;
while ( i < 2 && occludedByObjects == true )
{
pointOnLight = light->samplePointOnObject();
occludedByObjects = thisScene->Occluded(
intersectionInfo->intersectionPoint,
pointOnLight,
light
);
i++;
}
if ( occludedByObjects == false )
{
newRayDirection = Normalize( pointOnLight - intersectionInfo->intersectionPoint );
brdf->BRDF(
ray.direction,
newRayDirection,
attenuationFactor
);
attenuationFactor.Scaled_by_Spectrum_Value( obj->material_type->color );
// light pdf in angular form
// should be returned for MIS
light_pdf = light->PDF_in_solid_angle ( pointOnLight, intersectionInfo->intersectionPoint, newRayDirection );
// not sure !!!
double pointSamplePdf = light->PDF();
Ray nextRay( intersectionInfo->intersectionPoint, newRayDirection );
Vector normal_on_light;
light->getNormalDirection( pointOnLight, normal_on_light );
double geometryTerm = GeometricTerm( nextRay, normalDirection, pointOnLight, normal_on_light );
lightIntensity = light->emission;
lightSourceSamplingContribution = Attenuate_Light_Spectrum(
attenuationFactor,
lightIntensity
) * geometryTerm / pointSamplePdf;
}
else
{
if ( DebugMode )
{
printf( "Direct illimination can not sample a point on light source" );
}
}
}
inline Spectrum EstimateDirectIllumination (
const Scene * thisScene,
const Intersection * intersectionInfo,
const Ray & ray
)
{
Spectrum intensity;
Objects * obj = intersectionInfo->object;
BRDFModels * brdf = obj->brdf_model;
Vector newRayDirection;
Vector normalDirection;
normalDirection = intersectionInfo->normal;
Attenuation attenuationFactor;
bool delta_brdf_hitEmissive = false;
bool occludedByObjects = true;
Spectrum lightIntensity;
if ( obj->brdf_model->surfaceFlag == surface_delta )
{
// get reflection direction
// generate new ray
// intersect with scene to see if the ray hit a light source
normalDirection = intersectionInfo->normal;
attenuationFactor = brdf->SampleBRDF(
ray.direction,
newRayDirection,
normalDirection
);
Ray newRay( intersectionInfo->intersectionPoint, newRayDirection );
Intersection newIntersectionInfo;
if ( !thisScene->IntersectionWithScene( newRay, newIntersectionInfo ) )
return Spectrum();
if ( newIntersectionInfo.object->emitter == true )
{
delta_brdf_hitEmissive = true;
lightIntensity = newIntersectionInfo.object->emission;
attenuationFactor.Scaled_by_Spectrum_Value( obj->material_type->color );
intensity = Attenuate_Light_Spectrum(
attenuationFactor,
lightIntensity
);
}
}
else
{
Spectrum lightSourceSamplingContribution;
Spectrum brdfSamplingContribution;
// light source sampling evaluation
Objects * light;
light = thisScene->AquireOneOfEmissiveObjects();
double light_pdf = 0; // to be added
double brdf_pdf = 0;
double light_weight = 0;
double brdf_weight = 0;
Pnt3D pointOnLight;
int i = 0;
while ( i < 2 && occludedByObjects == true )
{
pointOnLight = light->samplePointOnObject();
occludedByObjects = thisScene->Occluded(
intersectionInfo->intersectionPoint,
pointOnLight,
light
);
i++;
}
if ( occludedByObjects == false )
{
newRayDirection = pointOnLight - intersectionInfo->intersectionPoint;
brdf->BRDF(
ray.direction,
newRayDirection,
attenuationFactor
);
attenuationFactor.Scaled_by_Spectrum_Value( obj->material_type->color );
// light pdf
light_pdf = light->PDF_in_solid_angle ( pointOnLight, intersectionInfo->intersectionPoint, newRayDirection );
// brdf_pdf = obj->brdf_model->PDF ( ray.direction , newRayDirection );
// geomery term????
// according to PBRT page 765, geometric term cancel out ???
Vector normal_on_light;
light->getNormalDirection( pointOnLight, normal_on_light );
double geometryTerm = GeometricTerm( ray, normalDirection, pointOnLight, normal_on_light );
lightIntensity = light->emission;
lightSourceSamplingContribution =
Attenuate_Light_Spectrum(
attenuationFactor,
lightIntensity
) * geometryTerm / light_pdf;
}
// evaluate BRDF sampling
if ( light->isDeltaEmitter == false )
{
attenuationFactor = brdf->SampleBRDF(
ray.direction,
newRayDirection,
normalDirection
);
Ray newRay( intersectionInfo->intersectionPoint, newRayDirection );
Intersection newIntersectionInfo;
if ( thisScene->IntersectionWithScene( newRay, newIntersectionInfo ) )
if ( newIntersectionInfo.object->emitter == true )
{
{
brdf_pdf = obj->brdf_model->PDF( ray.direction, newIntersectionInfo.normal, newRayDirection );
// weight = BalanceHeuristic ( 1 , brdf_pdf , 1 , light_pdf );
attenuationFactor.Scaled_by_Spectrum_Value( obj->material_type->color );
double cos_i = AbsDot( ray.direction, normalDirection );
brdfSamplingContribution += Attenuate_Light_Spectrum(
attenuationFactor,
newIntersectionInfo.object->emission
) * cos_i / brdf_pdf;
}
}
}
light_weight = light_pdf / ( brdf_pdf + light_pdf );
brdf_weight = brdf_pdf / ( brdf_pdf + light_pdf );
intensity += lightSourceSamplingContribution * light_weight;
intensity += brdfSamplingContribution * brdf_weight;
if ( intensity.HasNaNs() )
// printf ( "has nan" );
return Spectrum();
return intensity;
}
}