Inode *torus_intersect(Prim *p, Ray ro)
{
double a, b, c, disc, t0, t1;
Inode *i0, *i1;
Ray r = ray_transform(ro, p->ti);
a = v3_sqrnorm(r.d);
b = 2 * v3_dot(r.d, r.o);
c = v3_sqrnorm(r.o) - 1;
if ((disc = SQR(b) - 4 * a * c) <= 0)
return (Inode *)0;
t0 = (-b - sqrt(disc)) / (2 * a);
t1 = (-b + sqrt(disc)) / (2 * a);
if (t1 < RAY_EPS)
return (Inode *)0;
if (t0 < RAY_EPS) {
Vector3 n1 = v3_unit(torus_gradient(p, ray_point(r, t1)));
return inode_alloc(t1, n1, FALSE);
} else {
Vector3 n0 = v3_unit(torus_gradient(p, ray_point(ro, t0)));
Vector3 n1 = v3_unit(torus_gradient(p, ray_point(ro, t1)));
i0 = inode_alloc(t0, n0, TRUE);
i1 = inode_alloc(t1, n1, FALSE);
i0->next = i1;
return i0;
}
}
Color ray_shade(int level, Real w, Ray v, RContext *rc, Object *ol)
{
Inode *i = ray_intersect(ol, v);
if (i != NULL) { Light *l; Real wf;
Material *m = i->m;
Vector3 p = ray_point(v, i->t);
Cone recv = cone_make(p, i->n, PIOVER2);
Color c = c_mult(m->c, c_scale(m->ka, ambient(rc)));
rc->p = p;
for (l = rc->l; l != NULL; l = l->next)
if ((*l->transport)(l, recv, rc) && (wf = shadow(l, p, ol)) > RAY_WF_MIN)
c = c_add(c, c_mult(m->c,
c_scale(wf * m->kd * v3_dot(l->outdir,i->n), l->outcol)));
if (level++ < MAX_RAY_LEVEL) {
if ((wf = w * m->ks) > RAY_WF_MIN) {
Ray r = ray_make(p, reflect_dir(v.d, i->n));
c = c_add(c, c_mult(m->s,
c_scale(m->ks, ray_shade(level, wf, r, rc, ol))));
}
if ((wf = w * m->kt) > RAY_WF_MIN) {
Ray t = ray_make(p, refract_dir(v.d, i->n, (i->enter)? 1/m->ir: m->ir));
if (v3_sqrnorm(t.d) > 0) {
c = c_add(c, c_mult(m->s,
c_scale(m->kt, ray_shade(level, wf, t, rc, ol))));
}
}
}
inode_free(i);
return c;
} else {
return BG_COLOR;
}
}
static Real formfactor(int i, int j, int n, Poly **p, Real *a)
{
Vector3 vi, vj, vji, d;
Real r2, ci, cj;
vi = poly_centr(p[i]);
vj = poly_centr(p[j]);
vji = v3_sub(vi, vj);
if ((r2 = v3_sqrnorm(vji)) < REL_EPS)
return 0;
d = v3_scale(1.0/sqrt(r2), vji);
if ((cj = v3_dot(poly_normal(p[j]), d)) < REL_EPS)
return 0;
if ((ci = -v3_dot(poly_normal(p[i]), d)) < REL_EPS)
return 0;
if (vis_flag && visible(n, p, vj, vji) < REL_EPS)
return 0;
return a[i] * ((cj * ci) / (PI * r2 + a[i]));
}
