Create an Arc Object (.NET)

This example creates an arc in Model space with a center point of (6.25,9.125,0), a radius of 6, start angle of 1.117 (64 degrees), and an end angle of 3.5605 (204 degrees).

VB.NET

Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
 
<CommandMethod("AddArc")> _
Public Sub AddArc()
    '' Get the current document and database
    Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
    Dim acCurDb As Database = acDoc.Database

    '' Start a transaction
    Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()

        '' Open the Block table for read
        Dim acBlkTbl As BlockTable
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, OpenMode.ForRead)

        '' Open the Block table record Model space for write
        Dim acBlkTblRec As BlockTableRecord
        acBlkTblRec = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), _
                                        OpenMode.ForWrite)

        '' Create an arc that is at 6.25,9.125 with a radius of 6, and
        '' starts at 64 degrees and ends at 204 degrees
        Using acArc As Arc = New Arc(New Point3d(6.25, 9.125, 0), _
                                     6, 1.117, 3.5605)

            '' Add the new object to the block table record and the transaction
            acBlkTblRec.AppendEntity(acArc)
            acTrans.AddNewlyCreatedDBObject(acArc, True)
        End Using

        '' Save the new object to the database
        acTrans.Commit()
    End Using
End Sub

C#

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
 
[CommandMethod("AddArc")]
public static void AddArc()
{
    // Get the current document and database
    Document acDoc = Application.DocumentManager.MdiActiveDocument;
    Database acCurDb = acDoc.Database;

    // Start a transaction
    using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
    {
        // Open the Block table for read
        BlockTable acBlkTbl;
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                        OpenMode.ForRead) as BlockTable;

        // Open the Block table record Model space for write
        BlockTableRecord acBlkTblRec;
        acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                        OpenMode.ForWrite) as BlockTableRecord;

        // Create an arc that is at 6.25,9.125 with a radius of 6, and
        // starts at 64 degrees and ends at 204 degrees
        using (Arc acArc = new Arc(new Point3d(6.25, 9.125, 0),
                            6, 1.117, 3.5605))
        {

            // Add the new object to the block table record and the transaction
            acBlkTblRec.AppendEntity(acArc);
            acTrans.AddNewlyCreatedDBObject(acArc, true);
        }

        // Save the new line to the database
        acTrans.Commit();
    }
}

VBA/ActiveX Code Reference

Sub AddArc()
    ' Define the center point
    Dim ptCen(0 To 2) As Double
    ptCen(0) = 6.25: ptCen(1) = 9.125: ptCen(2) = 0#
 
    ' Create an Arc object in model space
    Dim arcObj As AcadArc
    Set arcObj = ThisDrawing.ModelSpace.AddArc(ptCen, 6#, 1.117, 3.5605)
 
    ThisDrawing.Application.ZoomAll
End Sub