- Skyline_pair (vector<Box> const &boxes, Real horizon_padding, Axis a);
- Skyline_pair (Box const &, Real horizon_padding, Axis a);
+ Skyline_pair (vector<Box> const &boxes, Axis a);
+ Skyline_pair (vector<Drul_array<Offset> > const &buildings, Axis a);
+ Skyline_pair (vector<Skyline_pair> const &skypairs);
+ Skyline_pair (Box const &, Axis a);
+
+ Real left () const;
+ Real right () const;