segment_t* actlist_find(actlist_t*a, point_t p1, point_t p2); // finds segment immediately to the left of p1 (breaking ties w/ p2)
void actlist_insert(actlist_t*a, point_t p1, point_t p2, segment_t*s);
void actlist_delete(actlist_t*a, segment_t*s);
segment_t* actlist_find(actlist_t*a, point_t p1, point_t p2); // finds segment immediately to the left of p1 (breaking ties w/ p2)
void actlist_insert(actlist_t*a, point_t p1, point_t p2, segment_t*s);
void actlist_delete(actlist_t*a, segment_t*s);