Convert segment of polyline into arc

[youssefGC]

Hi everyone,

How can I convert a segment of a polyline (where bulge ≠ 0) into an arc?

Thank you.

[_gile · Accepted solution]

Hi,

You can check if a polyline segment is an arc using the Polyline.GetSegmentType method.

If the result is SegmentType.Arc, you can get the corresponding CircularArc3d using the Polyline.GetArcSegmentAt method.

If needed, you can convert the returned CircularArc3d into an Arc entity with the Curve.CreateFromGeCurve mehod.

[youssefGC · Accepted solution]

Thank you. indeed, I tried to implement this code based on your method, and it works well for me.

[CommandMethod("ConvertToArc")]
        static public void runConversion()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            int indexOfArc = 0;
            PromptEntityResult acSSPrompt = ed.GetEntity("Select the polyline target");

            if (acSSPrompt.Status != PromptStatus.OK)
                return;

            using (Transaction Tx = db.TransactionManager.StartTransaction())
            {
                var btr = (BlockTableRecord)Tx.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
                Polyline pl = Tx.GetObject(acSSPrompt.ObjectId, OpenMode.ForRead) as Polyline;

                if (pl!=null && pl.GetSegmentType(indexOfArc) == SegmentType.Arc)
                {
                    CircularArc3d clrArc = pl.GetArcSegmentAt(indexOfArc);
                    //Arc newArc = new Arc(clrArc.Center, clrArc.Radius, clrArc.StartAngle, clrArc.EndAngle);
                    Arc newArc = Curve.CreateFromGeCurve(clrArc as Curve3d) as Arc;

                    newArc.ColorIndex = 1;
                    btr.AppendEntity(newArc);
                    Tx.AddNewlyCreatedDBObject(newArc, true);
                }
                Tx.Commit();
            }
        }