set startpoint for polyline

Anonymous — Wed, 25 Dec 2013 06:59:32 GMT

Hi All,

I have one question, hope everybody can help me. How can i set startpoint for polyline. And New StartPoint have to near Original System(O). I have attached image.

Re: set startpoint for polyline

Hallex — Wed, 25 Dec 2013 16:00:26 GMT

You can easily redraw this polyline, if this one

is have the straight segments only, here is a quick code for this case:

        ' for using to updating a straight polyline segments only
        <CommandMethod("repst", CommandFlags.Redraw)> _
        Public Shared Sub TestChangePolyStart()
            Dim doc As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
            Dim ed As Editor = doc.Editor
            Dim db As Database = doc.Database
            Dim ucs As CoordinateSystem3d = ed.CurrentUserCoordinateSystem.CoordinateSystem3d

            Dim osm As Object = Nothing

            Dim mat As Matrix3d = Matrix3d.AlignCoordinateSystem(Point3d.Origin, Vector3d.XAxis, Vector3d.YAxis, Vector3d.ZAxis, ucs.Origin, ucs.Xaxis, _
             ucs.Yaxis, ucs.Zaxis)

            Try
                Using doclock As DocumentLock = doc.LockDocument()
                    osm = Autodesk.AutoCAD.ApplicationServices.Application.GetSystemVariable("osmode")

                    Autodesk.AutoCAD.ApplicationServices.Application.SetSystemVariable("osmode", 1)

                    Dim peo1 As New PromptEntityOptions(vbLf & "Select a  polyline : ")

                    peo1.SetRejectMessage(vbLf & "You have to select polyline only!")

                    peo1.AddAllowedClass(GetType(Polyline), False)

                    Dim res1 As PromptEntityResult = ed.GetEntity(peo1)

                    If res1.Status <> PromptStatus.OK Then
                        Return
                    End If

                    Dim id As ObjectId = res1.ObjectId
                    Dim p1 As Point3d = res1.PickedPoint.TransformBy(mat)

                    Dim prOpt As New PromptPointOptions(vbLf & "Pick a new start vertex point: ")

                    Dim es As PromptPointResult = ed.GetPoint(prOpt)

                    If es.Status <> PromptStatus.OK Then
                        If es.Status = PromptStatus.Cancel Then
                            ed.WriteMessage(vbLf & "Interrupted by user")
                            Return
                        Else
                            ed.WriteMessage(vbLf & "Error on specifying a point")
                            Return
                        End If
                    End If

                    Dim new3dPt As Point3d = es.Value.TransformBy(mat)


                    Using tr As Transaction = db.TransactionManager.StartTransaction()
                        Dim poly As Polyline = DirectCast(tr.GetObject(id, OpenMode.ForRead), Polyline)

                        Dim wid As Double = poly.ConstantWidth

                        Dim new2dPt As New Point2d(new3dPt.X, new3dPt.Y)

                        Dim c As Integer = 0

                        Dim points As New List(Of Point2d)()
                        Dim sb As New StringBuilder()
                        For c = 0 To poly.NumberOfVertices - 1

                            points.Add(poly.GetPoint2dAt(c))
                        Next


                        Dim pos As Integer = points.IndexOf(new2dPt)

                        'Reverse List from given position using LINQ implementation

                        Dim tail As IEnumerable(Of Point2d) = points.Take(pos)

                        Dim head As IEnumerable(Of Point2d) = points.Except(tail)

                        Dim newpoints As IEnumerable(Of Point2d) = head.Concat(tail)

                        Dim pts As List(Of Point2d) = newpoints.ToList()
                        '________________________________________

                        Dim btr As BlockTableRecord = DirectCast(tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite), BlockTableRecord)

                        poly.UpgradeOpen()

                        Dim newpoly As New Polyline(poly.NumberOfVertices)

                        newpoly.Closed = poly.Closed

                        For c = 0 To pts.Count - 1
                            newpoly.AddVertexAt(c, CType(pts(c), Point2d), 0, wid, wid)
                        Next
                        newpoly.Closed = poly.Closed

                        btr.AppendEntity(newpoly)

                        tr.AddNewlyCreatedDBObject(newpoly, True)

                        newpoly.SetPropertiesFrom(poly)

                        poly.Erase()

                        tr.Commit()

                        ed.Regen()

                    End Using
                End Using
            Catch ex As System.Exception
                ed.WriteMessage(vbLf & "{0}", ex.StackTrace)
                Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument.Editor.WriteMessage(vbLf & "{0}" & vbLf & "{1}" & vbLf, ex.Message, ex.StackTrace)
            Finally
                Autodesk.AutoCAD.ApplicationServices.Application.SetSystemVariable("osmode", osm)
            End Try
        End Sub

Re: set startpoint for polyline

Anonymous — Thu, 26 Dec 2013 02:17:03 GMT

Thanks. If my polyline have arc(CircularArc2d), line... I will do the same above code.

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set startpoint for polyline

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Re: set startpoint for polyline