public static Polyline[] Intersection(IEnumerable <Polyline> a, IEnumerable <Polyline> b)
{
Clipper clipper = new Clipper(Clipper.ioStrictlySimple);
clipper.AddPaths(a.ToRegions(), PolyType.ptClip, true);
clipper.AddPaths(b.ToRegions(), PolyType.ptSubject, true);
PolyTree tree = new PolyTree();
clipper.Execute(ClipType.ctIntersection, tree);
double height = b.First()[0].Z;
return(tree.ToPolylines(height));
}
public static Polyline Offset(Polyline polyline, double distance)
{
if (polyline.Count < 2)
{
return(new Polyline());
}
var region = polyline.ToRegion();
var offset = new ClipperOffset();
offset.AddPath(region, JoinType.jtRound, EndType.etClosedPolygon);
PolyTree tree = new PolyTree();
offset.Execute(ref tree, distance / Tol);
var height = polyline[0].Z;
var first = tree.ToPolylines(height).MaxBy(p => p.Length).FirstOrDefault();
return(first ?? new Polyline(0));
}