Subject polygon
Contour 1
100	280
120	280
120	200
240	200
240	40
40	40
40	200
80	200
80	300
100	300
Clip polygon
Contour 1
80	280
280	280
280	40
240	80
200	80
240	120
200	160
220	200
200	240
160	200
120	200
80	160
