+Building
+Building::sloped_neighbour (Real horizon_padding, Direction d) const
+{
+ Real left = iv_[d];
+ Real right = iv_[d] + d * horizon_padding;
+ Real left_height = height_[d];
+ Real right_height = height_[d] - horizon_padding;
+ if (d == LEFT)
+ {
+ swap (left, right);
+ swap (left_height, right_height);
+ }
+ return Building (left, left_height, right_height, right);
+}
+