public BrdfToBtdf(SurfaceBsdf brdf)
{
this.brdf = brdf;
}
public static RgbSpectrum UniformSampleLights(ref Vector wo, IAccellerationStructure intersector,
SceneGeometryInfo scene, IList<ILight> lights, IntersectionInfo isect,
SurfaceBsdf bsdf, FastRandom rnd)
{
var Ld = new RgbSpectrum();
for (int index = 0; index < lights.Count; index++)
{
var lightsource = lights[index];
Ld += EstimateDirect(ref wo, intersector, scene, lightsource, isect, bsdf, rnd);
}
return Ld;
}
public static RgbSpectrum EstimateDirect(ref Vector wo, IAccellerationStructure intersector, SceneGeometryInfo scene, ILight light, IntersectionInfo isect, SurfaceBsdf bsdf, FastRandom rnd)
{
RgbSpectrum Ld = new RgbSpectrum();
Vector wi;
float lightPdf, bsdfPdf;
RayInfo shadowRay;
RgbSpectrum Li = light.Sample(ref isect.GeometryInfo.HitPoint, ref isect.GeometryInfo.GeoNormal, rnd.NextFloat(), rnd.NextFloat(), rnd.NextFloat(),
out shadowRay, out lightPdf);
if (lightPdf > 0f && !Li.IsBlack())
{
wi = -shadowRay.Dir;
RgbSpectrum f ;
bsdf.f(ref wo, ref wi, ref isect.GeometryInfo.GeoNormal, ref Ld, out f);
if (!f.IsBlack() && !intersector.Intersect(shadowRay))
{
// Add light's contribution to reflected radiance
//Li *= visibility.Transmittance(scene, renderer, NULL, rng, arena);
if (light.IsDelta)
Ld += f * Li * (Vector.AbsDot(ref wi, ref isect.GeometryInfo.GeoNormal) / lightPdf);
else
{
bsdfPdf = bsdf.Pdf(ref wo, ref wi, BxDFTypes.BSDF_ALL_TYPES);
float weight = MC.PowerHeuristic(1, lightPdf, 1, bsdfPdf);
Ld += f * Li * (Vector.AbsDot(ref wi, ref isect.GeometryInfo.GeoNormal) * weight / lightPdf);
}
}
}
if (!light.IsDelta)
{
//float bsdfPdf;
bool spb;
BsdfSampleData result;
bsdf.Sample_f(ref wo, ref isect.GeometryInfo.GeoNormal, ref isect.GeometryInfo.ShadingNormal, ref Ld, rnd.NextFloat(),
rnd.NextFloat(), rnd.NextFloat(), ref isect.TextureData, out result);
bsdfPdf = result.Pdf;
if (!result.F.IsBlack() && result.Pdf > 0f)
{
if (lightPdf > 0f)
{
float weight = MC.PowerHeuristic(1, bsdfPdf, 1, lightPdf);
IntersectionInfo lightIsect;
RgbSpectrum li = new RgbSpectrum();
var ray = new RayInfo(isect.GeometryInfo.HitPoint, result.Wi, 1e-4f, 1e+4f);
if (intersector.Intersect(ray, out lightIsect))
{
if (light is TriangleLight && lightIsect.PrimitiveId.Equals(((TriangleLight)light).Owner.Id))
li = light.Le(-result.Wi);
}
else
li = light.Le(ray.Dir);
if (!li.IsBlack())
{
//Li *= scene->Transmittance(ray);
Ld += result.F * li * Vector.AbsDot(ref result.Wi, ref isect.GeometryInfo.GeoNormal) * weight / bsdfPdf;
}
}
}
}
/*
if (!light->IsDeltaLight()) {
BxDFType flags = BxDFType(BSDF_ALL & ~BSDF_SPECULAR);
Spectrum f = bsdf->Sample_f(wo, &wi,
bs1, bs2, bcs, &bsdfPdf, flags);
if (!f.Black() && bsdfPdf > 0.) {
lightPdf = light->Pdf(p, n, wi);
if (lightPdf > 0.) {
// Add light contribution from BSDF sampling
float weight = PowerHeuristic(1, bsdfPdf, 1, lightPdf);
Intersection lightIsect;
Spectrum Li(0.f);
RayDifferential ray(p, wi);
if (scene->Intersect(ray, &lightIsect)) {
if (lightIsect.primitive->GetAreaLight() == light)
Li = lightIsect.Le(-wi);
}
else
Li = light->Le(ray);
if (!Li.Black()) {
Li *= scene->Transmittance(ray);
Ld += f * Li * AbsDot(wi, n) * weight / bsdfPdf;
}
}
}
}
*/
return Ld;
}
public static RgbSpectrum UniformSampleLight(ref Vector wo, IAccellerationStructure intersector,
SceneGeometryInfo scene, IList<ILight> lights, IntersectionInfo isect,
SurfaceBsdf bsdf, FastRandom rnd)
{
int nLights = lights.Count;
int lightNum = rnd.Next(0, nLights - 1);
var light = lights[lightNum];
return
(float)nLights *
EstimateDirect(ref wo, intersector, scene, light, isect, bsdf, rnd);
}
