public static Paths ClipPolygons(List<Polygon> polygons)
{
var subj = new Paths(polygons.Count);
var clip = new Paths(polygons.Count);
foreach (var polygon in polygons)
{
subj.Add(polygon.ToClipperPath());
clip.Add(polygon.ToClipperPath());
}
var solution = new Paths();
var c = new Clipper();
c.AddPaths(subj, PolyType.ptSubject, true);
c.AddPaths(clip, PolyType.ptClip, true);
c.Execute(ClipType.ctUnion, solution, PolyFillType.pftPositive, PolyFillType.pftEvenOdd);
return solution;
}