public bool Scatter(Ray ray, HitRecord hitRecord, ref Vector3 attentuation, ref Ray scattered)
{
var scatterDir = hitRecord.Normal + MathExt.RandomUnitVector();
if (Vector3Ext.NearZero(scatterDir))
{
scatterDir = hitRecord.Normal;
}
scattered = new Ray(hitRecord.Point, scatterDir, ray.Time);
attentuation = Albedo;
return(true);
}
public bool Scatter(Ray ray, HitRecord hitRecord, ref Vector3 attentuation, ref Ray scattered)
{
attentuation = Vector3.One;
float refractionRatio = hitRecord.FrontFace ? (1.0f / RefactionIndex) : RefactionIndex;
var unitDir = Vector3.Normalize(ray.Direction);
float cosTheta = Math.Min(Vector3.Dot(-unitDir, hitRecord.Normal), 1.0f);
float sinTheta = MathF.Sqrt(1.0f - cosTheta * cosTheta);
bool cannotRefract = refractionRatio * sinTheta > 1.0f;
Vector3 direction;
if (cannotRefract || Reflectance(cosTheta, refractionRatio) > MathExt.RandomFloat())
{
direction = Vector3.Reflect(unitDir, hitRecord.Normal);
}
else
{
direction = Vector3Ext.Refract(unitDir, hitRecord.Normal, refractionRatio);
}
scattered = new Ray(hitRecord.Point, direction, ray.Time);
return(true);
}