+ RoamPoint *l = triangle->p.l;
+ RoamPoint *m = triangle->p.m;
+ RoamPoint *r = triangle->p.r;
+ gdouble min_x = MIN(MIN(l->px, m->px), r->px);
+ gdouble max_x = MAX(MAX(l->px, m->px), r->px);
+ gdouble min_y = MIN(MIN(l->py, m->py), r->py);
+ gdouble max_y = MAX(MAX(l->py, m->py), r->py);