Spectrum PhotonMap::estimate_radiance(const Point& p, const Normal& nn,
const Vector& wo, const Bsdf& bsdf, float radius) const
{
(void)nn;
Spectrum power(0.f);
this->photon_tree.lookup(p, square(radius),
[&](const Photon& photon, float dist_square, float radius_square) {
(void)dist_square;
if(dot(photon.nn, nn) >= 0.7f) {
power += photon.power * bsdf.f(wo, photon.wi, BSDF_ALL);
}
return radius_square;
});
return power / (float(this->emitted_count) * PI * square(radius));
}
// private method of li
Spectrum InstantRadiosity::_li( const Ray& r , bool ignoreLe , float* first_intersect_dist ) const
{
// return if it is larger than the maximum depth
if( r.m_Depth > max_recursive_depth )
return 0.0f;
// get intersection from camera ray
Intersection ip;
if( false == scene.GetIntersect( r , &ip ) )
return ignoreLe?0.0f:scene.Le( r );
// eavluate light path less than two vertices
Spectrum radiance = ignoreLe?0.0f:ip.Le( -r.m_Dir );
unsigned light_num = scene.LightNum();
for( unsigned i = 0 ; i < light_num ; ++i )
{
const Light* light = scene.GetLight(i);
radiance += EvaluateDirect( r , scene , light , ip , LightSample(true) , BsdfSample(true) , BXDF_TYPE( BXDF_ALL ) );
}
if( first_intersect_dist )
*first_intersect_dist = ip.t;
// pick a virtual light source randomly
const unsigned lps_id = min( m_nLightPathSet - 1 , (int)(sort_canonical() * m_nLightPathSet) );
list<VirtualLightSource> vps = m_pVirtualLightSources[lps_id];
Bsdf* bsdf = ip.primitive->GetMaterial()->GetBsdf(&ip);
// evaluate indirect illumination
Spectrum indirectIllum;
list<VirtualLightSource>::const_iterator it = vps.begin();
while( it != vps.end() )
{
if( r.m_Depth + it->depth > max_recursive_depth )
{
++it;
continue;
}
Vector delta = ip.intersect - it->intersect.intersect;
float sqrLen = delta.SquaredLength();
float len = sqrt( sqrLen );
Vector n_delta = delta / len;
Bsdf* bsdf1 = it->intersect.primitive->GetMaterial()->GetBsdf(&(it->intersect));
float gterm = AbsDot( n_delta , ip.normal ) * AbsDot( n_delta , it->intersect.normal ) / max( m_fMinSqrDist , sqrLen );
Spectrum f0 = bsdf->f( -r.m_Dir , -n_delta );
Spectrum f1 = bsdf1->f( n_delta , it->wi );
Spectrum contr = gterm * f0 * f1 * it->power;
if( !contr.IsBlack() )
{
Visibility vis(scene);
vis.ray = Ray( it->intersect.intersect , n_delta , 0 , 0.001f , len - 0.001f );
if( vis.IsVisible() )
indirectIllum += contr;
}
++it;
}
radiance += indirectIllum / (float)m_nLightPaths;
if( m_fMinDist > 0.0f )
{
Vector wi;
float bsdf_pdf;
Spectrum f = bsdf->sample_f( -r.m_Dir , wi , BsdfSample( true ) , &bsdf_pdf );
if( !f.IsBlack() && bsdf_pdf != 0.0f )
{
PixelSample ps;
float gather_dist;
Ray gather_ray( ip.intersect , wi , r.m_Depth + 1 , 0.001f , m_fMinDist - 0.001f );
Spectrum li = _li( gather_ray , true , &gather_dist );
if( !li.IsBlack() )
{
float dgterm = AbsDot( wi , ip.normal ) * max( 0.0f , 1.0f - gather_dist * gather_dist / m_fMinSqrDist );
radiance += f * li * dgterm / bsdf_pdf;
}
}
}
return radiance;
}
