public bool Hit(Ray r, float t_min, float t_max, ref Hit_Record rec)
{
Vector3 oc = r.Origin - this.Center;
float a = r.Direction.LengthSquared();
float half_b = Vector3.Dot(oc, r.Direction);
float c = oc.LengthSquared() - this.Radius * this.Radius;
float discriminant = half_b * half_b - a * c;
if (discriminant > 0)
{
float root = (float)Math.Sqrt(discriminant);
float temp = (-half_b - root) / a;
if (temp < t_max && temp > t_min)
{
rec.T = temp;
rec.P = r.At(rec.T);
Vector3 outward_normal = (rec.P - this.Center) / this.Radius;
rec.Set_Face_Normal(r, outward_normal);
return(true);
}
temp = (-half_b + root) / a;
if (temp < t_max && temp > t_min)
{
rec.T = temp;
rec.P = r.At(rec.T);
Vector3 outward_normal = (rec.P - this.Center) / this.Radius;
rec.Set_Face_Normal(r, outward_normal);
return(true);
}
}
return(false);
}
public bool Hit(Ray r, float t_min, float t_max, ref Hit_Record rec)
{
Hit_Record temp_rec = default;
bool hit_anything = false;
float closest_so_far = t_max;
foreach (var o in this.Objects)
{
if (o.Hit(r, t_min, closest_so_far, ref temp_rec))
{
hit_anything = true;
closest_so_far = temp_rec.T;
rec = temp_rec;
}
}
return(hit_anything);
}
static Vector3 Ray_color(Ray r, HitTable world, int depth)
{
Hit_Record rec = default;
// If we've exceeded the ray bounce limit, no more light is gathered.
if (depth <= 0)
{
return(Vector3.Zero);
}
if (world.Hit(r, 0.001f, Helpers.Infinity, ref rec))
{
Vector3 target = rec.P + Helpers.Random_in_hemisphere(rec.Normal);
return(0.5f * Ray_color(new Ray(rec.P, target - rec.P), world, depth - 1));
}
Vector3 unit_direction = Vector3.Normalize(r.Direction);
var t = 0.5f * (unit_direction.Y + 1.0f);
return((1.0f - t) * new Vector3(1.0f, 1.0f, 1.0f) + t * new Vector3(0.5f, 0.7f, 1.0f));
}