public (Vec3 color, Ray ray) Scatter(Ray rIn, HitRecord hitRec)
{
var col = new Vec3(1, 1, 1);
var nOverNP = hitRec.IsFrontFace ? (1 / RefIndex) : RefIndex;
var unitDirection = rIn.Direction.Normalize();
var cosAlpha = Math.Min(MathR.Dot(unitDirection * -1, hitRec.N), 1.0F);
var sinAlpha = MathF.Sqrt(1.0F - (cosAlpha * cosAlpha));
// TIR
if (nOverNP * sinAlpha > 1)
{
var reflect = MathR.Reflect(unitDirection, hitRec.N);
var scatterRay = new Ray(hitRec.P, reflect);
return(col, scatterRay);
}
//Reflection
var reflectionProp = MathR.Schlick(cosAlpha, RefIndex);
if (Rand.Rand01() < reflectionProp)
{
var reflect = MathR.Reflect(unitDirection, hitRec.N);
var scatterRay = new Ray(hitRec.P, reflect);
return(col, scatterRay);
}
//Refraction
var refract = MathR.Refract(unitDirection, hitRec.N, nOverNP);
var scatterRay2 = new Ray(hitRec.P, refract);
return(col, scatterRay2);
}
public HitRecord(float t, Vec3 p, Vec3 n, Ray r, IMaterial material) : this()
{
(T, P, R, N, Material) = (t, p, r, n, material);
IsFrontFace = MathR.Dot(r.Direction, N) < 0;
N = IsFrontFace ? n : n * -1;
}