C＃clip linesegment with clipper library

我正在使用限幅器对多边形执行一系列操作，这些操作代表程序中对象的轮廓。 问题是，我现在想要剪切一个线段网格来填充这些轮廓，但我正在努力用Clipper做到这一点。

目前我将线条转换为厚度为2个单位的矩形，然后我进行交叉操作，最后我需要将新多边形恢复为线段。 这样效率很低，并且会产生很多错误。

这可以用Clipper完成，如果没有其他我可以使用或我需要实现我自己的线段剪辑器吗？

Answer 1

使用Clipper ver 6 …

using ClipperLib; using Path = List; using Paths = List>; static Polygon IntsToPolygon(Int64[] ints) { int len1 = ints.Length / 2; Polygon result = new Polygon(len1); for (int i = 0; i < len1; i++) result.Add(new IntPoint(ints[i * 2], ints[i * 2 + 1])); return result; } static void Main(string[] args) { Paths clip = new Paths(); //clipping polygon(s) //make a polygon in the shape of a pentagram //with center (200,200) and radius 100 ... Int64[][] ints1 = new Int64[][] { new Int64[]{222, 169, 295, 169, 236, 212, 259, 281, 200, 238, 141, 281, 164, 212, 105, 169, 178, 169, 200, 100} }; clip.Add(IntsToPolygon(ints1[0])); Paths subj = new Paths(); //subject paths, could be open or closed here int gridWidth = 5; int loopCnt = 200 / gridWidth; //now make grid lines and add them to subj ready for clipping ... //add horizontal grid lines ... for (int i = 0; i <= loopCnt; i++) { Path gridLine = new Path(2); gridLine.Add(new IntPoint(100, 100 + i * gridWidth)); gridLine.Add(new IntPoint(300, 100 + i * gridWidth)); subj.Add(gridLine); } //add vertical grid lines ... for (int i = 0; i <= loopCnt; i++) { Path gridLine = new Path(2); gridLine.Add(new IntPoint(100 + i * gridWidth, 100)); gridLine.Add(new IntPoint(100 + i * gridWidth, 300)); subj.Add(gridLine); } //now clip the gridlines (subj) with the pentagram (clip) ... Clipper c = new Clipper(); PolyTree solution = new PolyTree(); c.AddPaths(subj, PolyType.ptSubject, false); //ie paths NOT closed c.AddPaths(clip, PolyType.ptClip, true); //nb: clip paths MUST be closed c.Execute(ClipType.ctIntersection, solution, PolyFillType.pftEvenOdd, PolyFillType.pftEvenOdd); Paths clippedGrids = Clipper.PolyTreeToPaths(solution); //Display the result (sorry, make your own display function) ... //Display(Paths p, Color stroke, Color brush, PolyFillType pft, bool IsClosed) Display(subj, Color.FromArgb(0x18, 0, 0, 0x9c), Color.Blue, PolyFillType.NonZero, false); //unclipped grid Display(clippedGrids, FromArgb(0, 0, 0, 0), Color.Red, false); //clipped grid }