public override bool Scatter(ref Ray rIn, ref HitRecord rec, ref Point3 attenuation, ref Ray scattered)
{
attenuation = Colour.One;
float refractionRatio = rec.FrontFace ? (1f / IR) : IR;
Vector3 unitDirection = Vector3.Normalize(rIn.Direction);
float cosTheta = MathF.Min(Vector3.Dot(-unitDirection, rec.Normal), 1f);
float sinTheta = MathF.Sqrt(1f - cosTheta * cosTheta);
bool cannotRefract = refractionRatio * sinTheta > 1.0;
Vector3 direction;
if (cannotRefract || Reflectance(cosTheta, refractionRatio) > Program.random.NextDouble())
{
direction = Program.VecReflect(unitDirection, rec.Normal);
}
else
{
direction = Program.VecRefract(unitDirection, rec.Normal, refractionRatio);
}
scattered = new Ray(rec.P, direction);
return(true);
}
public override bool Hit(Ray r, float tMin, float tMax, ref HitRecord rec)
{
Vector3 oc = r.Origin - Centre;
float a = r.Direction.LengthSquared();
float halfB = Vector3.Dot(oc, r.Direction);
float c = oc.LengthSquared() - Radius * Radius;
float discriminant = halfB * halfB - a * c;
if (discriminant < 0)
{
return(false);
}
float sqrtd = MathF.Sqrt(discriminant);
// Find the nearest root that lies in the acceptable range.
float root = (-halfB - sqrtd) / a;
if (root < tMin || tMax < root)
{
root = (-halfB + sqrtd) / a;
if (root < tMin || tMax < root)
{
return(false);
}
}
rec.T = root;
rec.P = r.At(rec.T);
Vector3 outwardNormal = (rec.P - Centre) / Radius;
rec.SetFaceNormal(r, outwardNormal);
rec.Mat = Mat;
return(true);
}
public abstract bool Scatter(ref Ray rIn, ref HitRecord rec, ref Colour attenuation, ref Ray scattered);
public abstract bool Hit(Ray r, float t_min, float t_max, ref HitRecord rec);
