z := zone.containing(v<,start>)

Get the zone that encompasses the point v. The optional value start can be given to seed the search with the last zone found at that point. This zone is checked first and, if valid, will be the only zone check, speeding up the check.


z - the pointer to the zone containing that point, or null if no zone is found


v - the point in space being checked

start - optional starting zone to check first