libpolyclipping16 6.1.3a-2 (amd64 binary) in ubuntu trusty

 The Clipper library performs polygon clipping, polygon offsetting and polyline
 offsetting. All four boolean clipping operations are supported - intersection,
 union, difference and exclusive-or. Also, there are no restrictions on the
 types of polygons that can be clipped - they can have holes, be
 self-intersecting, have coincident edges etc.