the clip is polyline, the subject is polygon, can Clipper2 provide the fucntion?

[map-A]

I have a polygon, I want cut it by a polyline. For example, A rectangle is cut in the middle to become two rectangles.More general situation like follows:

[superlloyd]

line clipping seems to not be working (in C# at least) big bummer :(

[philstopford]

Scale up all of the geometry, use offset to widen the line into a quad of minimal width. Run the subtraction and scale back down again. The scaling will minimize the error introduced. If you're working with integer inputs, the scale down will snap the edges back into alignment.

[aismann]

@philstopford
Good idea. Thanks!

[superlloyd]

oh.. only saw the notification now.
using copilt suggestion I used Clipper1 (I found a nuget package compatible with .netdtandard2: ParagonClipper)

[aismann]

oh.. only saw the notification now. using copilt suggestion I used Clipper1 (I found a nuget package compatible with .netdtandard2: ParagonClipper)

Have you an example with data?

[superlloyd]

sorry... not good user of GitHub.. just did some cleanup and your message became more apaprent.
I use Clipper 1 & 2 in a home made drawing program in developement.. so that work fine!

Here are my package import:

<PackageReference Include="ParagonClipper" Version="6.4.2" />
<PackageReference Include="Clipper2" Version="1.5.4" />

Here is some Clipper1 code....

    public static List<ClipperLib.IntPoint> ToClipper1Path(this AbstractCurve g, double precision)
    {
        var scale = 1.0 / precision;
        var res = new List<ClipperLib.IntPoint>(g.Points.Count);
        foreach (var p in g.Points)
        {
            var p2 = g.Transform * p;
            res.Add(new ClipperLib.IntPoint(p2.X * scale, p2.Y * scale));
        }
        return res;
    }
    public static IEnumerable<Curve> ToCurves(this List<List<ClipperLib.IntPoint>> clippedLines, double precision)
    {
        foreach (var line in clippedLines)
        {
            var curve = new Curve();
            foreach (var ipoint in line)
                curve.Points.Add(new Point(ipoint.X * precision, ipoint.Y * precision));
            yield return curve;
        }
    }
   public static List<List<ClipperLib.IntPoint>> CutCurves(List<ClipperLib.IntPoint> iRing, ClipperLib.ClipType clipType, List<ClipperLib.IntPoint> other)
    {
        var clipper = new ClipperLib.Clipper();
        clipper.AddPath(other, ClipperLib.PolyType.ptSubject, false);
        clipper.AddPath(iRing, ClipperLib.PolyType.ptClip, true);

        var solution = new ClipperLib.PolyTree();
        clipper.Execute(clipType, solution);
        var clippedLines = ClipperLib.Clipper.PolyTreeToPaths(solution);

        return clippedLines;
    }

[woodiecm]

Is there already a solution for splitting one or more polygons using a polyline?

There really only needs to be an AddOpenClip function for this, right?

[LarsSkiba]

The problem you think you are solving is not well defined. Your geometry could wrap around that line in all possible ways.
You could achieve your desired output by other making the line reaally long and extend it to a rectangle enclosing "half" of your geometry or by making it a rectangle with 1 pixel width.