public override bool scatter(Ray r_in, Hit_Record rec, ref Vec3 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 = albedo;
return(Vec3.dot(scattered.direction(), rec.normal) > 0.0f);
}
public override bool hit(Ray r, float t_min, float t_max, ref Hit_Record rec)
{
Vec3 oc = r.origin() - center;
float a = r.direction().x() * r.direction().x() + r.direction().z() * r.direction().z();
float b = 2.0f * (oc.x() * r.direction().x() + oc.z() * r.direction().z());
float c = oc.x() * oc.x() + oc.z() * oc.z() - radius * radius;
float discriminant = b * b - 4 * a * c;
if (discriminant > 0.0f)
{
float temp = (-b - (float)Math.Sqrt(b * b - 4 * a * c)) / (2 * a);
if (temp < t_max && temp > t_min)
{
rec.t = temp;
rec.p = r.point_at_parameter(rec.t);
rec.normal = (rec.p - center) / radius;
rec.normal[1] = 0.0f;
rec.mat_type = mat_type;
Helper.get_sphere_uv(rec.p, ref rec.u, ref rec.v);
return(true);
}
temp = (-b + (float)Math.Sqrt(b * b - 4 * a * c)) / (2 * a);
if (temp < t_max && temp > t_min)
{
rec.t = temp;
rec.p = r.point_at_parameter(rec.t);
rec.normal = (rec.p - center) / radius;
rec.normal[1] = 0.0f;
rec.mat_type = mat_type;
Helper.get_sphere_uv(rec.p, ref rec.u, ref rec.v);
return(true);
}
}
return(false);
}
public override bool hit(Ray r, float t_min, float t_max, ref Hit_Record rec)
{
// Perform a simplified Pythagorean in 3D to determine if
// the ray vector intersects with the sphere.
Vec3 oc = r.origin() - center;
float a = Vec3.dot(r.direction());
float b = Vec3.dot(oc, r.direction());
float c = Vec3.dot(oc) - radius * radius;
float discriminant = b * b - a * c;
if (discriminant > 0.0f)
{
float temp = (-b - (float)Math.Sqrt(b * b - a * c)) / a;
if (temp < t_max && temp > t_min)
{
rec.t = temp;
rec.p = r.point_at_parameter(rec.t);
rec.normal = (rec.p - center) / radius;
rec.mat_type = mat_type;
Helper.get_sphere_uv(rec.p, ref rec.u, ref rec.v);
return(true);
}
temp = (-b + (float)Math.Sqrt(b * b - a * c)) / a;
if (temp < t_max && temp > t_min)
{
rec.t = temp;
rec.p = r.point_at_parameter(rec.t);
rec.normal = (rec.p - center) / radius;
rec.mat_type = mat_type;
Helper.get_sphere_uv(rec.p, ref rec.u, ref rec.v);
return(true);
}
}
return(false);
}
public override bool scatter(Ray r_in, Hit_Record rec, ref Vec3 attenuation, ref Ray scattered)
{
Vec3 outward_normal;
Vec3 reflected = Vec3.reflect(r_in.direction(), rec.normal);
float ni_over_nt;
attenuation = color;
Vec3 refracted = new Vec3(1.0f, 0.0f, 0.0f);
float reflect_prob;
float cosine;
if (Vec3.dot(r_in.direction(), rec.normal) > 0.0f)
{
outward_normal = -rec.normal;
ni_over_nt = ref_idx;
cosine = ref_idx * Vec3.dot(r_in.direction(), rec.normal) / r_in.direction().length();
}
else
{
outward_normal = rec.normal;
ni_over_nt = 1.0f / ref_idx;
cosine = -Vec3.dot(r_in.direction(), rec.normal) / r_in.direction().length();
}
if (refract(r_in.direction(), outward_normal, ni_over_nt, ref refracted))
{
reflect_prob = schlick(cosine, ref_idx);
}
else
{
scattered = new Ray(rec.p, reflected);
reflect_prob = 1.0f;
}
if (Rng.f() < reflect_prob)
{
scattered = new Ray(rec.p, reflected); // reFLEcted
}
else
{
scattered = new Ray(rec.p, refracted); // reFRActed
}
return(true);
}
public static Vec3 color(Ray r, int depth)
{
Hit_Record rec;
rec.t = 0.0f;
rec.u = rec.v = 0.0f;
rec.p = null;
rec.normal = null;
rec.mat_type = null;
if (world.hit(r, 0.001f, float.MaxValue, ref rec))
{
Ray scattered = new Ray();
Vec3 attenuation = new Vec3();
Vec3 emitted = rec.mat_type.emitted(rec.u, rec.v, rec.p);
if (depth < ConfigParams.max_bounces && rec.mat_type.scatter(r, rec, ref attenuation, ref scattered))
{
// recursive call, finding color of each object hit
return(emitted + attenuation * color(scattered, depth + 1));
}
else
{
// too many bounces, or did not scatter (it absorbed the photon)
//return new Vec3(0.0f, 0.0f, 0.0f); // return black
return(emitted);
}
}
else
{
// we hit nothing, so now hit the outer sky
if (sky_active_flag)
{
Vec3 unit_direction = Vec3.unit_vector(r.direction());
// Return a linear interpolation of the sky, based on Y (vertical)
// Higher is more white, lower is more blue-gray.
float t = 0.5f * (unit_direction.y() + 1.0f);
return((1.0f - t) * new Vec3(1.0f, 1.0f, 1.0f) + t * new Vec3(0.5f, 0.7f, 1.0f));
}
return(new Vec3(0.0f, 0.0f, 0.0f)); // black sky
}
}
