working hack. now do it properly with intervals

[csgray] / src / geom.c

diff --git a/src/geom.c b/src/geom.c
index dba62ed..1961aed 100644 (file)
--- a/src/geom.c
+++ b/src/geom.c
@@ -101,9 +101,6 @@ struct hit *ray_sphere(struct ray *ray, csg_object *o)
                t[1] = tmp;
        }
 
-       if(t[0] < EPSILON) t[0] = EPSILON;
-       if(t[1] < EPSILON) t[1] = EPSILON;
-
        hitlist = hit = alloc_hits(2);
        for(i=0; i<2; i++) {
                float c[3] = {0, 0, 0};
@@ -139,15 +136,16 @@ struct hit *ray_plane(struct ray *ray, csg_object *o)
 
        xform_ray(&locray, o->ob.inv_xform);
 
+       ndotr = o->plane.nx * locray.dx + o->plane.ny * locray.dy + o->plane.nz * locray.dz;
+       if(fabs(ndotr) < EPSILON) return 0;
+
        vx = o->plane.nx * o->plane.d - locray.x;
        vy = o->plane.ny * o->plane.d - locray.y;
        vz = o->plane.nz * o->plane.d - locray.z;
 
        ndotv = o->plane.nx * vx + o->plane.ny * vy + o->plane.nz * vz;
-       if(fabs(ndotv) < EPSILON) return 0;
 
-       ndotr = o->plane.nx * locray.dx + o->plane.ny * locray.dy + o->plane.nz * locray.dz;
-       t = ndotr / ndotv;
+       t = ndotv / ndotr;
 
        if(t > EPSILON) {
                hit = alloc_hits(1);
@@ -186,9 +184,50 @@ struct hit *ray_csg_isect(struct ray *ray, csg_object *o)
        return 0;
 }
 
+static struct hit *first(struct hit *hlist)
+{
+       return hlist;
+}
+
+static struct hit *last(struct hit *hlist)
+{
+       while(hlist->next) {
+               hlist = hlist->next;
+       }
+       return hlist;
+}
+
 struct hit *ray_csg_sub(struct ray *ray, csg_object *o)
 {
-       return 0;
+       struct hit *hita, *hitb, *lasthit, tmp;
+
+       hita = ray_intersect(ray, o->sub.a);
+       hitb = ray_intersect(ray, o->sub.b);
+
+       if(!hita) return 0;
+       if(!hitb) return hita;
+
+       if(first(hita)->t < first(hitb)->t) {
+               free_hit_list(hitb);
+               return hita;
+       }
+       if(first(hita)->t < (lasthit = last(hitb))->t) {
+               /* overlapping */
+               tmp = *hitb;
+               *hitb = *lasthit;
+
+               free_hit_list(tmp.next);
+
+               hitb->nx = -hitb->nx;
+               hitb->ny = -hitb->ny;
+               hitb->nz = -hitb->nz;
+
+               free_hit_list(hita);
+               return hitb;
+       }
+
+       free_hit_list(hitb);
+       return hita;
 }