static inline t_color recursive_tracer(t_params p, t_ray *ray, t_objects *sp)
{
t_f64 inside;
t_f64 facingratio;
t_f64 fresneleffect;
t_vec3f refldir;
t_vec3f refdir;
t_color reflection;
t_color refrac;
t_ray rx;
if ((inside = dot_vec3f(&ray->dir, &p.nhit) > 0))
p.nhit = scale_vec3f(&p.nhit, -1);
facingratio = -dot_vec3f(&ray->dir, &p.nhit);
fresneleffect = mix(pow(1 - facingratio, 3), 1, .1);
refldir = get_reflection_dir(&p.nhit, &ray->dir);
rx = reflected_ray(ray, &refldir, &p.nhit, &p.phit);
reflection = trace_ray(&rx, sp, ++p.depth);
if (p.sphere->transparency > 0)
{
refdir = compute_ideal_refractions(ray, inside, p);
rx = refracted_ray(ray, &refdir, &p.nhit, &p.phit);
refrac = trace_ray(&rx, sp, ++p.depth);
}
return (defualt_glossy_shading(&reflection,
&refrac, fresneleffect, p.sphere));
}
std::tuple<bool, double, Ray> a4_refract(const Point3D& hit, const Vector3D& direction, const Vector3D& n, double ni)
{
Ray refracted_ray(Point3D(0.0, 0.0, 0.0), Vector3D(0.0, 0.0, 0.0));
double R = 1.0;
Vector3D normal = n;
double cosI = direction.dot(normal);
double n1, n2;
if(cosI > 0)
{
// direction and normal are in the same direction so ray originates from inside primitive
n1 = ni;
n2 = 1.0;
normal = -normal;
}
else
{
// Ray enters primitive from outside
n1 = 1.0;
n2 = ni;
cosI = -cosI;
}
// Check for total internal reflection
double nr = n1 / n2;
double cosT = 1.0 - (nr * nr) * (1.0 - (cosI * cosI));
if(cosT >= 0)
{
cosT = sqrt(cosT);
// Compute Fresnel coefficient
double a = (n1 * cosI - n2 * cosT) / (n1 * cosI + n2 * cosT);
double b = (n2 * cosI - n1 * cosT) / (n2 * cosI + n1 * cosT);
R = ((a * a) + (b * b)) * 0.5;
// Cast the refracted ray
refracted_ray = Ray(hit - (1e-9) * normal, nr * direction + (nr * cosI - cosT) * normal);
}
return std::tuple<bool, double, Ray>(cosT < 0, R, refracted_ray);
}
