hit_test intersect(ray r, object obj) {
v3 ro = r.origin;
v3 rd = r.direction;
double t;
hit_test ht_out;
switch (obj.tag) {
case SPHERE: {
v3 sc = obj.o.s.center;
double sr = obj.o.s.radius;
v3 A = v3_sub(ro, sc);
double B = v3_dot(A, rd);
double C = v3_dot(A, A) - sr*sr;
double D = B*B - C;
t = -B - sqrt(D);
if (D > 0 && t > 0) {
v3 ray_pos = ray_position(r, t);
ht_out.miss = HIT;
ht_out.t = t;
ht_out.hit_point = ray_pos;
ht_out.surf = \
(*(obj.o.s.surface_color))(obj.o.s.center, ray_pos);
ht_out.shine = obj.o.s.shine;
ht_out.surf_norm = v3_norm(v3_sub(ray_pos, obj.o.s.center));
} else {
ht_out.miss = MISS;
}
break;
}
case POSTER: {
v3 n = v3_expr(0, 0, -1);
double d = obj.o.p.upper_left.z;
t = -(v3_dot(ro, n) + d) / v3_dot(rd, n);
v3 ray_pos = ray_position(r, t);
if (t > 0 && is_on_poster(ray_pos, obj.o.p)) {
ht_out.miss = HIT;
ht_out.t = t;
ht_out.hit_point = ray_pos;
ht_out.surf = \
(*(obj.o.p.surface_color))(obj.o.p.upper_left, ray_pos);
ht_out.shine = obj.o.p.shine;
ht_out.surf_norm = n;
} else {
ht_out.miss = MISS;
}
break;
}
default:
fprintf(stderr, "error in intersect: unrecognized tag\n");
exit(1);
}
return ht_out;
}
/* intersect_sphere : intersect func for spheres */
hit_test intersect_sphere(ray r, object obj)
{
sphere s = obj.o.s;
hit_test result;
xyz A = xyz_sub(r.origin, s.center);
double B = xyz_dot(A, xyz_norm(r.dir));
double C = xyz_dot(A, A) - s.radius*s.radius;
double D = B*B - C;
double t = -B - sqrt(D);
ray newr = {r.origin, xyz_norm(r.dir)};
xyz loc = ray_position(newr,t);
xyz v = xyz_sub(loc, s.center);
xyz norm = xyz_norm(v);
if(D<=0 || t<=0)
result.miss = MISS;
else {
result.miss = HIT;
result.t = t;
result.hit_point = loc;
result.surf = s.surface_color(&obj, loc);
result.shine = s.shine;
result.surf_norm = norm;
}
return result;
}
/* intersect_poster : intersect func for posters */
hit_test intersect_poster(ray r, object obj)
{
poster p = obj.o.p;
hit_test result;
xyz n = xyz_expr(0, 0, -1);
double d = p.upper_left.z;
xyz rd = xyz_norm(r.dir);
double t = -(xyz_dot(r.origin, n) + d)/xyz_dot(rd, n);
ray newr = {r.origin, rd};
xyz loc = ray_position(newr,t);
xyz ul = p.upper_left;
if (t>0 &&
loc.x>=ul.x &&
loc.x<=(ul.x+p.w) &&
loc.y<=ul.y &&
loc.y>=(ul.y-p.h)) {
result.miss = HIT;
result.t = t;
result.hit_point = loc;
result.surf = p.surface_color(&obj, loc);
result.shine = p.shine;
result.surf_norm = n;
} else {
result.miss = MISS;
}
return result;
}
rgb lighting(scene s, ray r, hit_test h)
{
rgb result;
if (h.miss)
return s.bg;
vec hit_position = ray_position(r, h.dist);
if (shadow(hit_position, s.light, s.spheres)) {
result = rgb_modulate(h.surf, s.amb);
}
else {
double dot = vec_dot(h.surf_norm, s.light.direction);
double d = double_max(0, dot);
rgb diffuse_light = rgb_scale(d, s.light.color);
rgb lsum = rgb_add(s.amb, diffuse_light);
result = rgb_modulate(h.surf, lsum);
}
/**** === implement specular reflection here === ****/
if (rgb_nonzero(h.shine)) {
rgb ss;
vec N = h.surf_norm;
vec L = s.light.direction;
rgb S = h.shine;
vec R = vec_sub( vec_scale(2* vec_dot(N,L),N),L);
vec V = vec_neg(r.direction);
if (vec_dot(N,L)>0){
ss = rgb_scale( pow( double_max( vec_dot(R,V),0), 6), S);
//rgb_print(k);
}
else
ss = rgb_expr(0,0,0);
return rgb_add(result,ss);
}
return result;
}
/* color of the intersecting fsphere (if there is one) */
hit_test fintersect(ray r, fsphere s, timestamp ts)
{
hit_test result = {0}; /* {0} to quiet the compiler */
vec sc = s.center;
double sr = s.radius;
vec A = vec_sub(r.origin, sc);
double B = vec_dot(A, r.direction);
double C = vec_dot(A, A) - (sr * sr);
double D = (B * B) - C;
double t = (-B - sqrt(D));
result.miss = 1;
if (D > 0 && t > 0) {
result.miss = 0;
result.dist = t;
result.surf = s.compute_surf(s.center, ray_position(r,t), ts);
result.shine = s.compute_shine(ts);
result.surf_norm = vec_norm(vec_sub(ray_position(r,t),sc));
}
return result;
}
hit_test intersect_cylinder (ray r, cylinder c) {
hit_test result;
v3 rp = v3_expr(r.direction.x,0,r.direction.z);
double mp = v3_mag(rp);
v3 np = v3_norm(rp);
double xbar = r.origin.x - c.center.x;
double zbar = r.origin.z - c.center.z;
double a = pow(np.x,2) + pow(np.z,2);
double b = 2 * ( (xbar*np.x) + (zbar*np.z) );
double c1 = pow(xbar,2) + pow(zbar,2) - pow(c.radius,2);
double d = pow(b,2) - (4*a*c1);
result.miss = MISS;
if(d >= 0) {
double t_front = (-b - sqrt(d)) / (2*a);
double t_back = (-b + sqrt(d)) / (2*a);
v3 p_front = ray_position(r, t_front/mp);
v3 p_back = ray_position(r, t_back/mp);
if( (t_front < t_back) &&
(t_front > 0) &&
(p_front.y >= c.center.y) && (on_cylinder(p_front, c))) {
result.miss = HIT;
result.t = (t_front/mp);
result.hit_point = p_front;
result.surf = c.surface_color(c.center, p_front);
result.shine = c.shine;
v3 c2 = v3_expr(c.center.x, p_front.y, c.center.z);
result.surf_norm = v3_norm(v3_sub(p_front,c2));
} else if( (t_back > 0) &&
(p_back.y >= c.center.y) &&
(on_cylinder(p_back, c)) ) {
result.miss = HIT;
result.t = (t_back/mp);
result.hit_point = p_back;
result.surf = c.surface_color(c.center, p_back);
result.shine = c.shine;
v3 c3 = v3_expr(c.center.x, p_back.y, c.center.z);
result.surf_norm = v3_norm(v3_sub(c3,p_back));
}
}
return result;
}
hit_test intersect_poster (ray r, poster p)
{
hit_test result = {0};
v3 ro = r.origin;
v3 rd = r.direction;
v3 n = v3_expr(0, 0, -1);
double d = p.upper_left.z;
double t = -(v3_dot(ro, n) + d) / v3_dot(rd, n);
result.miss = MISS;
v3 intersection = ray_position(r, t);
if (t>0 && within_poster(intersection, p)) {
result.miss = HIT;
result.t = t;
result.hit_point = intersection;
result.surf = p.surface_color(p.upper_left, intersection);
result.shine = p.shine;
result.surf_norm = n;
}
return result;
}
hit_test intersect_sphere (ray r, sphere s)
{
hit_test result = {0};
v3 sc = s.center;
double sr = s.radius;
v3 a = v3_sub(r.origin, sc);
double b = v3_dot(a, r.direction);
double c = v3_dot(a, a) - (sr * sr);
double d = (b * b) - c;
double t = -b - sqrt(d);
result.miss = MISS;
if (d > 0 && t > 0) {
v3 intersection = ray_position(r, t);
result.miss = HIT;
result.t = t;
result.hit_point = intersection;
result.surf = s.surface_color(sc, intersection);
result.shine = s.shine;
result.surf_norm = v3_norm(v3_sub(intersection, sc));
}
return result;
}
color bg = color_expr(0,0,0.25);
poster p = poster_expr(xyz_expr(-1.5,1.5,4.5), 3, 3,
tex_green, color_expr(0,0,0));
object o1 = {POSTER, {.p = p}, NULL};
obj_list *os = ol_singleton(o1);
scene scn;
scn.bg = bg;
scn.objects = os;
stage stg = {cam, scn};
camera tcam = {xyz_expr(0,0,-1), 120, 120};
xyz loc1 = logical_loc(tcam,60,51);
xyz loc2 = logical_loc(tcam,1,0);
xyz loc3 = logical_loc(tcam,60,80);
ray orgray = {cam.loc, xyz_sub(loc1,cam.loc)};
hit_test ht = intersect(orgray, o1);
xyz htpt = ray_position(orgray,ht.t);
double d1 = dist(xyz_expr(-1.5,1.5,4.5),htpt);
double d2 = sqrt(p.w*p.w+p.h*p.h);
printf("\n\n *** testing intersect ***\n");
xyz_show(stdout,htpt);
hit_test_show(stdout,ht);
printf("\n\n *** testing dist ***\n");
printf("%.2lf %2.lf %.2lf\n",d1,d2,d1/d2);
color c = color_expr(d1/d2,0,0);
color_show(stdout,c);
printf("\n\n *** testing logica_loc *** \n");