public override zwischenSpeicher scatter(ray r_in, hit_record rec, Vektor attenuation, ray scattered)
{
zwischenSpeicher zw = new zwischenSpeicher();
attenuation = new Vektor(1, 1, 1);
double refraction_ratio = rec.front_face ? (1 / ir) : ir;
Vektor unit_direction = Vektor.unit_Vektor(r_in.Direction);
double cos_theta = Math.Min(Vektor.dot(unit_direction * -1, rec.normal), 1);
double sin_theta = Math.Sqrt(1 - cos_theta * cos_theta);
bool cannot_refract = refraction_ratio * sin_theta > 1;
Vektor direction;
if (cannot_refract)
{
direction = Vektor.reflect(unit_direction, rec.normal);
}
else
{
direction = Vektor.refract(unit_direction, rec.normal, refraction_ratio);
}
scattered = new ray(rec.p, direction);
zw.attenuation = attenuation;
zw.scattered = scattered;
zw.IsTrue = true;
return(zw);
}
public static Vektor refract(Vektor uv, Vektor n, double etai_over_etat)
{
var cos_theta = Math.Min(Vektor.dot(uv * -1, n), 1);
Vektor r_out_perp = etai_over_etat * (uv + cos_theta * n);
Vektor r_out_parallel = -Math.Sqrt(Math.Abs(1 - r_out_perp.length_squared())) * n;
return(r_out_perp + r_out_parallel);
}
public static double hit_sphere(Vektor center, double radius, ray r)
{
Vektor oc = r.Origin - center;
var a = r.Direction.length_squared();
var half_b = Vektor.dot(oc, r.Direction);
var c = oc.length_squared() - radius * radius;
var discriminant = half_b * half_b - a * c;
if (discriminant < 0)
{
return(-1);
}
else
{
return((-half_b - Math.Sqrt(discriminant)) / a);
}
}
public override zwischenSpeicher Hit(ray r, double t_min, double t_max, hit_record rec)
{
zwischenSpeicher zw = new zwischenSpeicher();
Vektor oc = r.Origin - center;
var a = r.Direction.length_squared();
var half_b = Vektor.dot(oc, r.Direction);
var c = oc.length_squared() - radius * radius;
var discriminant = half_b * half_b - a * c;
if (discriminant < 0)
{
zw.IsTrue = false;
return(zw);
}
var sqrtd = Math.Sqrt(discriminant);
var root = (-half_b - sqrtd) / a;
if (root < t_min || t_max < root)
{
root = (-half_b + sqrtd) / a;
if (root < t_min || t_max < root)
{
zw.IsTrue = false;
return(zw);
}
}
rec.t = root;
rec.p = r.at(rec.t);
Vektor outward_normal = (rec.p - center) / radius;
rec.set_face_normal(r, outward_normal);
rec.mat_ptr = mat_ptr;
zw.rec = rec;
zw.IsTrue = true;
return(zw);
}
