private static Vector3[] PerlinGenerate()
{
Vector3[] res = new Vector3[256];
for (int i = 0; i < 256; i++)
{
res[i] = new Vector3(2 * VectorHelpers.RandomFloat() - 1, 2 * VectorHelpers.RandomFloat() - 1, 2 * VectorHelpers.RandomFloat() - 1).GetUnitVector();
}
return(res);
}
private static int[] PerlinGeneratePerm()
{
int[] res = new int[256];
for (int i = 0; i < 256; i++)
{
res[i] = i;
}
// Permute the array of 0..255
for (int i = 0; i < 256; i++)
{
int swithedIndex = (int)((i + 1) * VectorHelpers.RandomFloat());
int temp = res[i];
res[i] = res[swithedIndex];
res[swithedIndex] = temp;
}
return(res);
}
public override bool Scatter(Ray r, HitRecord hitRecord, out Vector3 attenuation, out Ray scattered)
{
attenuation = Vector3.One;
Vector3 reflected = VectorHelpers.Reflect(r.Direction, hitRecord.SurfaceNormal);
Vector3 outwardNormal;
float niOverNt;
float cosine;
if (Vector3.Dot(r.Direction, hitRecord.SurfaceNormal) > 0)
{
outwardNormal = -hitRecord.SurfaceNormal;
niOverNt = RefractiveIndex;
cosine = RefractiveIndex * Vector3.Dot(r.Direction, hitRecord.SurfaceNormal) / r.Direction.Length();
}
else
{
outwardNormal = hitRecord.SurfaceNormal;
niOverNt = 1.0f / RefractiveIndex;
cosine = -Vector3.Dot(r.Direction, hitRecord.SurfaceNormal) / r.Direction.Length();
}
float reflectProb = 1.0f;
if (Refract(r.Direction, outwardNormal.GetUnitVector(), niOverNt, out Vector3 refracted))
{
reflectProb = Schlick(cosine);
}
if (VectorHelpers.RandomFloat() < reflectProb)
{
scattered = new Ray(hitRecord.HitPoint, reflected);
}
else
{
scattered = new Ray(hitRecord.HitPoint, refracted);
}
return(true);
}