-void Layout3D::add_track(Track3D &t)
-{
- insert_unique(tracks, &t.get_track(), &t);
-}
-
-void Layout3D::remove_track(Track3D &t)
-{
- tracks.erase(&t.get_track());
-}
-
-Track3D &Layout3D::get_track(Track &t) const
-{
- return *get_item(tracks, &t);
-}
-
-void Layout3D::add_vehicle(Vehicle3D &v)