use Perl

• Answer the negative (Score:1)

  by rhesa (5696) on 2008.06.09 5:24 (#63247) Journal

  The rectangles _don't_ overlap when one is either completely to the left of the other, or completely below the other.
  
  A rectangle can be defined by the coordinates of its top-left and bottom-right points:
  
  So let's say A = (x1,y1,x2,y2) and B = (u1,v1,u2,v2).

  (x1,y1)                 (u1,v1)
    +-------------+           +-----------+
    |             |           |           |
    |     A       |           |     B     |
    |             |           |           |
    +-------------+           +-----------+
                (x2,y2)                 (u2,v2)

  Then A does not overlap B if one of these four tests pass:

  # A left of B
  x2 < u1
  # A right of B
  x1 > u2
  # A above B
  y2 > v1
  # A below B
  y1 < v2

  So A overlaps B if none of the above hold:

    not ( x2 < u1 or x1 > u2 or y2 > v1 or y1 < v2 )

  or equivalently ( !(a or b) <=> !a and !b )

    x2 >= u1 and x1 <= u2 and y2 <= v1 and y1 >= v2

  That's too simple to be a module :-)
  
  

  Reply to This