topic Re: Remove colinear vertices polyline in .NET Forum

Remove colinear vertices polyline

MGO-Norsyn — Sat, 13 Nov 2021 22:01:33 GMT

Hi everybody.

I was searching for a method to remove colinear vertices from polyline today and couldn't find any thing readily available, so I had to write my own and I want to share this method with anybody needing it in the future.

public static void RemoveColinearVerticesPolyline(Polyline pline) { List<int> verticesToRemove = new List<int>(); for (int i = 0; i < pline.NumberOfVertices - 1; i++) { SegmentType st1 = pline.GetSegmentType(i); SegmentType st2 = pline.GetSegmentType(i + 1); if (st1 == SegmentType.Line && st1 == st2) { LineSegment2d ls2d1 = pline.GetLineSegment2dAt(i); LineSegment2d ls2d2 = pline.GetLineSegment2dAt(i + 1); if (ls2d1.IsColinearTo(ls2d2)) verticesToRemove.Add(i + 1); } } verticesToRemove.Reverse(); pline.UpgradeOpen(); for (int j = 0; j < verticesToRemove.Count; j++) pline.RemoveVertexAt(verticesToRemove[j]); }

Re: Remove colinear vertices polyline

_gile — Sun, 14 Nov 2021 08:15:50 GMT

Hi,

Here's an example which works with linera and coincident segments.

Re: Remove colinear vertices polyline

_gile — Sun, 14 Nov 2021 18:32:04 GMT

This one also deals with concentric arc segments.

public static void RemoveColinearVerticesPolyline(Polyline pline) { for (int i = 0; i < pline.NumberOfVertices - 1; i++) { if (pline.GetSegmentType(i) == SegmentType.Coincident) { pline.RemoveVertexAt(i); i--; } else if (pline.GetSegmentType(i) == SegmentType.Line) { var segment = pline.GetLineSegment2dAt(i); switch (pline.GetSegmentType(i + 1)) { case SegmentType.Line: if (pline.GetLineSegment2dAt(i + 1).IsColinearTo(segment)) { pline.RemoveVertexAt(i + 1); i--; } break; case SegmentType.Coincident: pline.RemoveVertexAt(i + 1); i--; break; default: break; } } else if (pline.GetSegmentType(i) == SegmentType.Arc) { var segment = pline.GetArcSegment2dAt(i); switch (pline.GetSegmentType(i + 1)) { case SegmentType.Arc: var nextSegment = pline.GetArcSegment2dAt(i + 1); if (segment.Center.IsEqualTo(nextSegment.Center) && segment.IsClockWise == nextSegment.IsClockWise) { double bulge = Math.Tan( Math.Atan(pline.GetBulgeAt(i)) + Math.Atan(pline.GetBulgeAt(i + 1))); pline.RemoveVertexAt(i + 1); pline.SetBulgeAt(i, bulge); i--; } break; case SegmentType.Coincident: pline.RemoveVertexAt(i + 1); i--; break; default: break; } } } }

Re: Remove colinear vertices polyline

MGO-Norsyn — Mon, 15 Nov 2021 09:19:13 GMT

Hi, thanks for you input, I am sure it will be useful for someone in the future. 😉

I have one question though, I have not tested your methods, but does it really work with polyline's vertices being deleted when iterating over them? I tried that in my method first, but it messed up the vertice's numbers so it was not correct.

I solved it by gathering vertice numbers, then reversing the list with numbers, then removing the vertices starting with the highest number vertice first, så it wouldn't mess up the iteration.

But I see you do the removing the vertices up front and it really works?

Re: Remove colinear vertices polyline

_gile — Mon, 15 Nov 2021 11:07:56 GMT

Test it and you'll see it really works...

Re: Remove colinear vertices polyline

_gile — Mon, 15 Nov 2021 15:20:14 GMT

Re: Remove colinear vertices polyline

MGO-Norsyn — Mon, 15 Nov 2021 15:23:08 GMT

Great!

Re: Remove colinear vertices polyline

MGO-Norsyn — Tue, 22 Feb 2022 15:36:57 GMT

Here is my take on removing collinear vertices on a Polyline3d:

PromptEntityOptions peo = new PromptEntityOptions("\nSelect pline 3d: "); peo.AddAllowedClass(typeof(Polyline3d), true); PromptEntityResult per = editor.GetEntity(peo); Polyline3d pline = per.ObjectId.Go<Polyline3d>(tx); List<int> verticesToRemove = new List<int>(); PolylineVertex3d[] vertices = pline.GetVertices(tx); for (int i = 0; i < vertices.Length - 2; i++) { PolylineVertex3d vertex1 = vertices[i]; PolylineVertex3d vertex2 = vertices[i + 1]; PolylineVertex3d vertex3 = vertices[i + 2]; Vector3d vec1 = vertex1.Position.GetVectorTo(vertex2.Position); Vector3d vec2 = vertex2.Position.GetVectorTo(vertex3.Position); if (vec1.IsCodirectionalTo(vec2, Tolerance.Global)) verticesToRemove.Add(i + 1); } Point3dCollection p3ds = new Point3dCollection(); for (int i = 0; i < vertices.Length; i++) { if (verticesToRemove.Contains(i)) continue; PolylineVertex3d v = vertices[i]; p3ds.Add(v.Position); } Polyline3d nyPline = new Polyline3d(Poly3dType.SimplePoly, p3ds, false); nyPline.AddEntityToDbModelSpace(localDb); nyPline.Layer = pline.Layer; pline.CheckOrOpenForWrite(); pline.Erase(true);

Re: Remove colinear vertices polyline

bcddss — Thu, 21 Mar 2024 22:18:26 GMT

Hi. You can attach the dll file because not everyone has a visual studio to build the dll file. Thank you

Re: Remove colinear vertices polyline

kerry_w_brown — Thu, 21 Mar 2024 23:02:33 GMT

@bcddss wrote:
Hi. You can attach the dll file because not everyone has a visual studio to build the dll file. Thank you

With due respect :

This is a peer to peer programming support group, NOT a shopping center.

Re: Remove colinear vertices polyline

bcddss — Fri, 22 Mar 2024 05:10:51 GMT

I understand that this peer-to-peer programming support group focuses on providing guidance and assistance rather than directly sharing files. Thank you for your assistance. My bad, sorry for inconvenience.

Re: Remove colinear vertices polyline

kibitotato — Fri, 21 Jun 2024 12:02:08 GMT

HOW CAN I USE THIS. I M USED TO USE LISP BUT NOT THIS.

Re: Remove colinear vertices polyline

Ed__Jobe — Fri, 21 Jun 2024 14:16:46 GMT

@kibitotato wrote:

HOW CAN I USE THIS. I M USED TO USE LISP BUT NOT THIS.

You have to learn C# and the .NET api or you can translate this to lisp. Take a look at the (vlax-curve-????) functions.

BTW, typing in all caps is like yelling.