public override bool hit(Ray r, double t_min, double t_max, ref hit_record rec)
{
Vec3 oc = r.origin - center;
var a = r.direction.length_squared();
var half_b = Vec3.dot(oc, r.direction);
var c = oc.length_squared() - radius * radius;
var discriminant = half_b * half_b - a * c;
if (discriminant < 0)
{
return(false);
}
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)
{
return(false);
}
}
rec.t = root;
rec.p = r.at(rec.t);
Vec3 outward_normal = (rec.p - center) / radius;
rec.set_face_normal(r, outward_normal);
rec.mat_prt = this.mat;
return(true);
}
public override bool scatter(Ray r_in, hit_record rec, ref Color attenuation, ref Ray scattered)
{
Vec3 reflected = Vec3.reflect(Vec3.unit_vector(r_in.direction), rec.normal);
scattered = new Ray(rec.p, reflected + fuzz * Vec3.random_in_unit_sphere());
attenuation = this.albedo;
return(Vec3.dot(scattered.direction, rec.normal) > 0);
}
public override bool scatter(Ray r_in, hit_record rec, ref Color attenuation, ref Ray scattered)
{
var scatter_direction = rec.normal + Vec3.random_unit_vector();
if (scatter_direction.near_zero())
{
scatter_direction = rec.normal;
}
scattered = new Ray(rec.p, scatter_direction);
attenuation = albedo;
return(true);
}
public virtual bool hit(Ray r, double t_min, double t_max, ref hit_record rec)
{
hit_record temp_rec = new hit_record();
bool hit_anything = false;
var closest_so_far = t_max;
foreach (Hittable hittable in hittables)
{
if (hittable.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);
}
public override bool scatter(Ray r_in, hit_record rec, ref Color attenuation, ref Ray scattered)
{
attenuation = new Color(1.0, 1.0, 1.0);
double refraction_ration = rec.front_face ? (1.0 / ir) : ir;
Vec3 unit_direction = Vec3.unit_vector(r_in.direction);
double cos_theta = Math.Min(Vec3.dot(-unit_direction, rec.normal), 1.0);
double sin_theta = Math.Sqrt(1.0 - cos_theta * cos_theta);
bool cannot_refract = refraction_ration * sin_theta > 1.0;
Vec3 direction = new Vec3();
if (cannot_refract || reflectance(cos_theta, refraction_ration) > Utilities.random_double())
{
direction = Vec3.reflect(unit_direction, rec.normal);
}
else
{
direction = Vec3.refract(unit_direction, rec.normal, refraction_ration);
}
scattered = new Ray(rec.p, direction);
return(true);
}
public virtual bool scatter(Ray r_in, hit_record rec, ref Color attenuation, ref Ray scattered) => false;
public virtual bool hit(Ray r, double t_min, double t_max, ref hit_record rec) => false;