public void Add(Bxdf bxdf)
{
_bxdfs.Add(bxdf);
}
public Spectrum SampleF(Vector woW, out Vector wiW, BsdfSample bsdfSample,
out float pdf, out BxdfType sampledType, BxdfType flags = BxdfType.All)
{
// Choose which _BxDF_ to sample
int matchingComps = NumComponents(flags);
if (matchingComps == 0)
{
wiW = Vector.Zero;
pdf = 0.0f;
sampledType = 0;
return(Spectrum.CreateBlack());
}
int which = Math.Min(
MathUtility.Floor(bsdfSample.UComponent * matchingComps),
matchingComps - 1);
Bxdf bxdf = null;
int count = which;
foreach (var eachBxdf in _bxdfs)
{
if (eachBxdf.MatchesFlags(flags) && count-- == 0)
{
bxdf = eachBxdf;
break;
}
}
Debug.Assert(bxdf != null);
// Sample chosen _BxDF_
Vector wo = WorldToLocal(woW);
Vector wi;
pdf = 0.0f;
Spectrum f = bxdf.SampleF(wo, out wi, bsdfSample.UDir0, bsdfSample.UDir1, out pdf);
if (pdf == 0.0f)
{
wiW = Vector.Zero;
sampledType = 0;
return(Spectrum.CreateBlack());
}
sampledType = bxdf.Type;
wiW = LocalToWorld(wi);
// Compute overall PDF with all matching _BxDF_s
if (!bxdf.Type.HasFlag(BxdfType.Specular) && matchingComps > 1)
{
foreach (var eachBxdf in _bxdfs)
{
if (eachBxdf != bxdf && eachBxdf.MatchesFlags(flags))
{
pdf += bxdf.Pdf(wo, wi);
}
}
}
if (matchingComps > 1)
{
pdf /= matchingComps;
}
// Compute value of BSDF for sampled direction
if (!bxdf.Type.HasFlag(BxdfType.Specular))
{
f = Spectrum.CreateBlack();
if (Vector.Dot(wiW, _ng) * Vector.Dot(woW, _ng) > 0) // ignore BTDFs
{
flags &= ~BxdfType.Transmission;
}
else // ignore BRDFs
{
flags &= ~BxdfType.Reflection;
}
foreach (var eachBxdf in _bxdfs)
{
if (eachBxdf.MatchesFlags(flags))
{
f += eachBxdf.F(wo, wi);
}
}
}
return(f);
}
public void Add(Bxdf bxdf)
{
_bxdfs.Add(bxdf);
}
