if(out_ep<0)
break;
Track *next = track->get_links()[out_ep];
if(!next || next == start)
break;
ep = next->get_endpoint_by_link(*track);
if(out_ep<0)
break;
Track *next = track->get_links()[out_ep];
if(!next || next == start)
break;
ep = next->get_endpoint_by_link(*track);