Active Contributor
Posts: 42
Registered: ‎11-06-2012
Message 1 of 4 (562 Views)
Accepted Solution

Offset polyline by pick point on side like autocad

562 Views, 3 Replies
02-03-2013 05:32 PM

Hi pro,


Please let me know how to offset a opened polyline by pick point on side of opened polyline.



Posts: 1,346
Registered: ‎04-09-2008
Message 2 of 4 (544 Views)

Re: Offset polyline by pick point on side like autocad

02-04-2013 02:16 AM in reply to: xdbk07

With minimum error checking. Only as idea.

using System;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.EditorInput;

[assembly: CommandClass(typeof(Rivilis.CurveUtils))]

namespace Rivilis
  public class CurveUtils
    [CommandMethod("OffsetCurve", CommandFlags.Modal)]
    public static void OffsetCurve()
      Document doc = Application.DocumentManager.MdiActiveDocument;
      Editor ed = doc.Editor;
      PromptDoubleResult resValueOff = ed.GetDistance("\nOffset value: ");
      if (resValueOff.Status != PromptStatus.OK) return;
      PromptPointResult  resPointOff = ed.GetPoint("\nOffset side: ");
      if (resPointOff.Status != PromptStatus.OK) return;
      PromptEntityOptions prCurv = new PromptEntityOptions("\nSelect curve: ");
      prCurv.SetRejectMessage("not a Curve");
      PromptEntityResult resCurv = ed.GetEntity(prCurv);
      if (resCurv.Status != PromptStatus.OK) return;
      using  (Transaction tr = doc.TransactionManager.StartTransaction()) {
        Curve curve = tr.GetObject(resCurv.ObjectId, OpenMode.ForRead) as Curve;
        if (curve != null) {
          BlockTableRecord btr = tr.GetObject(curve.BlockId, OpenMode.ForWrite) as BlockTableRecord;
          if (btr != null) {
            Point3d pDir = (Point3d)(Application.GetSystemVariable("VIEWDIR"));
            if (pDir != null) {
              Point3d pWCS = resPointOff.Value.TransformBy(ed.CurrentUserCoordinateSystem);
              double offset = IsRightDirection(curve, pWCS, pDir.GetAsVector()) ? resValueOff.Value : -resValueOff.Value;
              DBObjectCollection curvCols = curve.GetOffsetCurves(offset);
              foreach (DBObject obj in curvCols) {
                Curve subCurv = obj as Curve;
                if (subCurv != null) {
                  tr.AddNewlyCreatedDBObject(subCurv, true);
    // Detect side of point
    public static bool IsRightDirection(Curve pCurv, Point3d p, Vector3d vDir)
      Vector3d vNormal = Vector3d.ZAxis;
      if (pCurv.IsPlanar) {
        Plane plane = pCurv.GetPlane();
        vNormal = plane.Normal;
        p = p.Project(plane, vDir);
      Point3d pNear = pCurv.GetClosestPointTo(p, true);
      Vector3d vSide = p - pNear;
      Vector3d vDeriv = pCurv.GetFirstDerivative(pNear);
      if (vNormal.CrossProduct(vDeriv).DotProduct(vSide) < 0.0)
        return true;
        return false;



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*Expert Elite*
Posts: 1,561
Registered: ‎10-08-2008
Message 3 of 4 (535 Views)

Re: Offset polyline by pick point on side like autocad

02-04-2013 03:34 AM in reply to: Alexander.Rivilis

Nice solution

Hats off

Cheers :smileyhappy:

Active Contributor
Posts: 42
Registered: ‎11-06-2012
Message 4 of 4 (510 Views)

Re: Offset polyline by pick point on side like autocad

02-05-2013 12:05 AM in reply to: Alexander.Rivilis


Great.It worked OK.

Thank Rivilis,

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