Spectrum Path::computeLi( const vec2f &pFilm, const SceneData &i_scene, const Camera &i_camera, const Sampler &i_sampler, int i_depth )
{
Camera::CameraSample cameraSample;
cameraSample.pixelSample = pFilm + i_sampler.sample2D();
cameraSample.lensSample = i_sampler.sample2D();
Ray ray;
float weight = i_camera.generateRay( cameraSample, &ray );
// Radiance
Spectrum L = Spectrum( 0.0f );
// Importance
Spectrum beta = Spectrum( 1.0 );
for ( int bounces = 0;; bounces++ ) {
RayIntersection intersection;
bool foundIntersection = i_scene.intersect( ray, intersection );
float maxDepth = 5;
if ( !foundIntersection || bounces >= maxDepth ) {
break;
}
Spectrum Le = intersection.Le();
if ( Le.isBlack() )
{
// Direct illumination sampling
Spectrum Ld = beta * uniformSampleOneLight( intersection, i_sampler, i_scene );
L += Ld;
// BSDF Sampling
const shading::BSDF &bsdf = intersection.getBSDF();
const vec3f &surfacePosition = intersection.getSurfacePoint().pos;
vec3f woLocal = -intersection.worldToSurface( -intersection.dir );
vec3f wiLocal;
float pdf = 1.0;
const vec2f &bsdfSample = i_sampler.sample2D();
Spectrum f = bsdf.sampleF( woLocal, &wiLocal, bsdfSample, &pdf );
// No point of continuing if no color
if ( f.isBlack() || pdf == 0.0 ) {
break;
}
// Transform to world space
vec3f wiWorld = intersection.surfaceToWorld( wiLocal );
// Generate new ray
ray = Ray( surfacePosition, wiWorld );
beta *= ( f * absDot( wiWorld, intersection.getSurfacePoint().normal ) ) / pdf;
// Russian Roulette
if ( beta.y() < 1.0f && bounces > 3 ) {
float q = std::max( .05f, 1 - beta.maxComponentValue() );
if ( i_sampler.sample1D() > q ) {
beta /= ( 1.0 - q );
}
else {
break;
}
}
}
else {
L += beta * intersection.Le() / 50.0;
break;
}
}
return weight * L;
}
Spectrum Path::estimateDirectLighting( const RayIntersection i_intersection, RenderablePtr i_light, const Sampler &i_sampler, const SceneData &i_scene )
{
// Direct contribution
Spectrum Ld = Spectrum::black();
float lightPdf = 0.0f;
float surfacePdf = 0.0f;
vec3f wiWorld;
const vec3f &woWorld = -i_intersection.dir;
const vec3f &woLocal = i_intersection.worldToSurface( woWorld );
const vec3f &normal = i_intersection.getSurfacePoint().normal;
const shading::BSDF &bsdf = i_intersection.getBSDF();
/* ==================== */
/* Sample Light */
/* ==================== */
{
VisibilityTester visibilityTester;
const vec3f &uLight = i_sampler.sample3D();
Spectrum Li = i_light->sampleIncidenceRadiance( i_intersection, uLight, &wiWorld, &lightPdf, &visibilityTester );
// Convert to local (surface) coords
const vec3f &wiLocal = i_intersection.worldToSurface( wiWorld );
// Sample light
if ( !Li.isBlack() && lightPdf > 0.0f ) {
const Spectrum &f = bsdf.computeF( woLocal, wiLocal ) * absDot( wiWorld, normal );
surfacePdf = bsdf.pdf( woLocal, wiLocal );
if ( !f.isBlack() ) {
// Ray is in shadow
if ( visibilityTester.isOccluded( i_scene ) ) {
Li = Spectrum::black();
}
if ( !Li.isBlack() ) {
// Weight with MIS
float misWeight = powerHeuristic( lightPdf, surfacePdf );
Ld += ( Li * f * misWeight ) / lightPdf;
}
}
}
}
/* ==================== */
/* Sample BSDF */
/* ==================== */
{
const vec2f &uSurface = i_sampler.sample2D();
vec3f wiLocal;
const Spectrum &f = bsdf.sampleF( woLocal, &wiLocal, uSurface, &surfacePdf ) * absDot( wiWorld, normal );
if ( !f.isBlack() && surfacePdf > 0.0f ) {
// TODO computer light PDF
lightPdf = 0.0;
// No contribution, return
if ( lightPdf == 0.0 ) {
return Ld;
}
// Convert to local (surface) coords
vec3f wiWorld = i_intersection.surfaceToWorld( wiLocal );
const Ray bsdfRay = Ray( i_intersection.getSurfacePoint().pos, wiWorld );
RayIntersection lightIntersection;
bool foundIntersection = i_scene.intersect( bsdfRay, lightIntersection );
Spectrum Li = Spectrum::black();
if ( foundIntersection ) {
if ( lightIntersection.m_shapeId == i_light->getIdentifier() ) {
Li = i_light->computeRadiance( lightIntersection.getSurfacePoint(), wiWorld );
}
}
if ( !Li.isBlack() ) {
// Weight with MIS
float misWeight = powerHeuristic( lightPdf, surfacePdf );
Ld += ( Li * f * misWeight ) / surfacePdf;
}
}
}
return Ld;
}