bool ray_sphere_intersect(t_ray *ray, t_sphere *sphere)
{
float a;
float b;
float c;
float discriminant;
bool retvalue;
t_vector distance;
a = vector_scalar(&ray->direction, &ray->direction);
distance = vector_sub(&ray->camera, &sphere->origin);
b = 2 * vector_scalar(&ray->direction, &distance);
c = vector_scalar(&distance, &distance) - (sphere->radius * sphere->radius);
discriminant = b * b - 4 * a * c;
if (discriminant < 0)
retvalue = false;
else
{
float sqrtdiscr = sqrtf(discr);
float t0 = (-B + sqrtdiscr)/(2);
float t1 = (-B - sqrtdiscr)/(2);
if(t0 > t1)
t0 = t1;
if((t0 > 0.001f) && (t0 < *t)){
*t = t0;
retval = true;
}else
retval = false;
}
return (retval);
}
void ray_pointon(Vector &result, const Ray &r, float t){
vector_add(result, vector_scalar(dir, t), p);
}
struct vector raytrace(struct vector rayorig, struct vector raydir, sphere_t *spheres, int nspheres, int depth)
{
int inside;
int i, j; /* Loop indexes. */
float t0;
float t1;
sphere_t s;
struct vector surface_color; /* Color of the surface. */
struct vector phit; /* Point of intersection. */
struct vector nhit; /* Normal at the intersection point. */
struct vector lightdir; /* Light direction. */
struct vector refldir;
struct vector refrdir;
struct vector tmp1, tmp3;
struct vector reflection;
struct vector refraction;
float tnear;
float facingratio;
float fresneleffect;
float ior;
float cosi;
float k;
float eta;
int transmission;
t0 = INFINITY;
t1 = INFINITY;
tnear = INFINITY;
s = NULL;
/*
* Find closest sphere in the scene
* that the ray intercepts.
*/
for (i = 0; i < nspheres; i++)
{
/* This sphere is intercepted. */
if (sphere_intersects(spheres[i], rayorig, raydir, &t0, &t1))
{
if (t0 < 0)
t0 = t1;
/* Closest sphere found. */
if (t0 < tnear)
{
tnear = t0;
s = spheres[i];
}
}
}
/*
* There is no intersection
* so return background color.
*/
if (s == NULL)
return (VECTOR(2, 2, 2));
surface_color = VECTOR(0, 0, 0);
phit = vector_scalar(raydir, tnear);
phit = vector_add(phit, rayorig);
nhit = vector_sub(phit, sphere_center(s));
nhit = vector_normalize(nhit);
inside = 0;
if (vector_dot(raydir, nhit) > 0)
{
nhit = vector_invert(nhit);
inside = 1;
}
tmp3 = vector_scalar(nhit, BIAS);
tmp3 = vector_add(tmp3, phit);
if (((s->transparency > 0) || (s->reflection > 0)) && (depth < max_depth))
{
facingratio = -vector_dot(raydir, nhit);
fresneleffect = mix(pow(1 - facingratio, 3), 1, 0.1);
tmp1 = vector_scalar(nhit, 2*vector_dot(raydir, nhit));
refldir = vector_sub(raydir, tmp1);
refldir = vector_normalize(refldir);
reflection = raytrace(tmp3, refldir, spheres, nspheres, depth + 1);
refraction = VECTOR(0, 0, 0);
if (s->transparency > 0)
{
ior = 1.1;
eta = (inside) ? ior : 1/ior;
cosi = -vector_dot(nhit, raydir);
k = 1 - eta*eta*(1 - cosi*cosi);
refrdir = vector_scalar(raydir, eta);
tmp1 = vector_scalar(nhit, eta*cosi - sqrt(k));
refrdir = vector_add(refrdir, tmp1);
refrdir = vector_normalize(refrdir);
tmp3 = vector_scalar(nhit, BIAS);
tmp3 = vector_sub(phit, tmp3);
refraction = raytrace(tmp3, refrdir, spheres, nspheres, depth + 1);
}
refraction =vector_scalar(refraction,(1-fresneleffect)*s->transparency);
reflection = vector_scalar(reflection, fresneleffect);
tmp1 = vector_add(reflection, refraction);
surface_color = vector_cross(tmp1, s->surface_color);
}
else
{
/*
* It is a diffuse object, so there
* is no need to raytrace any further.
*/
for (i = 0; i < nspheres; i++)
{
/* This is a light source. */
if (spheres[i]->emission_color.x > 0)
{
transmission = 1;
lightdir = vector_sub(spheres[i]->center, phit);
lightdir = vector_normalize(lightdir);
for (j = 0; j < nspheres; j++)
{
if (i == j)
continue;
/* Shade this point. */
if (sphere_intersects(spheres[j], tmp3, lightdir, NULL, NULL))
{
transmission = 0;
break;
}
}
if (transmission)
{
tmp1 = vector_scalar(s->surface_color, max(0, vector_dot(nhit, lightdir)));
tmp1 = vector_cross(tmp1, spheres[i]->emission_color);
surface_color = vector_add(surface_color, tmp1);
}
}
}
}
return (vector_add(surface_color, s->emission_color));
}
