private Collection < String > getNeighborGroups ( Tile tile ) { final Collection < String > neighborGroups = new ArrayList <> ( TransitionType . BITS ) ; addNeighborGroup ( neighborGroups , tile , 1 , - 1 ) ; addNeighborGroup ( neighborGroups , tile , - 1 , - 1 ) ; addNeighborGroup ( neighborGroups , tile , 1 , 1 ) ; addNeighborGroup ( neighborGroups , tile , - 1 , 1 ) ; return neighborGroups ; }
Get the direct neighbor angle groups .