Tree::R3pm

  use Tree::R;
  my $rtree = Tree::R->new
  for my $object (@objects) {
      my @bbox = $object->bbox(); # (minx,miny,maxx,maxy)
      $rtree->insert($object,@bbox);
  }
  my @point = (123, 456); # (x,y)
  my @results;
  $rtree->query_point(@point,\@results);
  for my $object (@results) {
      # point is in object's bounding box
  }
  my @rect = (123, 456, 789, 1234); # (minx,miny,maxx,maxy)
  @results = ();
  $rtree->query_completely_within_rect(@rect,\@results);
  for my $object (@results) {
      # object is within rectangle
  }
  @results = ();
  $rtree->query_partly_within_rect(@rect,\@results);
  for my $object (@results) {
      # object's bounding box and rectangle overlap
  }