question: public AboveVisitor ( Mask mask , RegionFunction function , int baseY ) { super ( mask , function ) ; checkNotNull ( mask ) ; this . baseY = baseY ; Collection < Vector > directions = getDirections ( ) ; directions . clear ( ) ; directions . add ( new Vector ( 1 , 0 , 0 ) ) ; directions . add ( new Vector ( - 1 , 0 , 0 ) ) ; directions . add ( new Vector ( 0 , 0 , 1 ) ) ; directions . add ( new Vector ( 0 , 0 , - 1 ) ) ; directions . add ( new Vector ( 0 , 1 , 0 ) ) ; directions . add ( new Vector ( 0 , - 1 , 0 ) ) ; }
target:  Create a new visitor.