public override Vector3D SampleF(ref ShadeRec sr, ref Vector3D wo, out Vector3D wi, out double pdf)
{
double NDotWo = sr.Normal.DotProduct(wo);
Vector3D r = -wo + 2.0 * sr.Normal.ScaleBy(NDotWo);
Vector3D w = r;
Vector3D u = new Vector3D(0.00424, 1, 0.00764).CrossProduct(w).Normalize().ToVector3D();
Vector3D v = u.CrossProduct(w);
Vector3D sp = SamplerRef.SampleHemisphere();
wi = sp.X * u + sp.Y * v + sp.Z * w;
if (sr.Normal.DotProduct(wi) < 0.0)
{
wi = -sp.X * u - sp.Y * v + sp.Z * w;
}
double phong_lobe = Math.Pow(r * wi, Exp);
pdf = phong_lobe * (sr.Normal.DotProduct(wi));
return(Cs.ScaleBy(phong_lobe).ScaleBy(Ks));
}
public override Vector3D SampleF(ref ShadeRec sr, ref Vector3D wo, out Vector3D wi, out double pdf)
{
Vector3D w = sr.Normal;
Vector3D v = new Vector3D(0.0034, 1, 0.0071);
v = v.CrossProduct(w);
v = v.Normalize().ToVector3D();
Vector3D u = v.CrossProduct(w);
Vector3D sp = SamplerRef.SampleHemisphere();
wi = sp.X * u + sp.Y * v + sp.Z * w;
wi = wi.Normalize().ToVector3D();
pdf = (float)(sr.Normal * wi * (1.0 / Math.PI));
return(Cd.ScaleBy(Kd * (1.0 / Math.PI)));
}
public Vector3D GetDirection(ref ShadeRec sr)
{
return(SamplerRef.SampleHemisphere());
}
public override Vector3D Sample()
{
Vector2D SP = SamplerRef.SampleUnitSquare();
return(p0 + a.ScaleBy(SP.X) + b.ScaleBy(SP.Y));
}
