static public IPolygon Merge(this List<IPolygon> polygons)
{
Clipper c = new Clipper();
foreach (var polygon in polygons)
{
c.AddPaths(polygon.ToClipperPolygons(), PolyType.ptSubject, true);
}
ClipperPolygons result = new ClipperPolygons();
if (c.Execute(ClipType.ctUnion, result, PolyFillType.pftPositive) == true)
{
return result.ToPolygon();
}
return null;
}
static public IPolygon Clip(this IPolygon clippee, Envelope clipper)
{
var clippeePolygons = clippee.ToClipperPolygons();
var clipperPolygons = clipper.ToPolygon().ToClipperPolygons();
var c = new Clipper();
c.AddPaths(clippeePolygons, PolyType.ptSubject, true);
c.AddPaths(clipperPolygons, PolyType.ptClip, true);
ClipperPolygons result = new ClipperPolygons();
if (c.Execute(ClipType.ctIntersection, result) == true)
{
return result.ToPolygon();
}
return clippee;
}