Tạo Line nối 2 điểm AutoCAD bằng VB.Net

Public Sub AddLine(ByVal X1, ByVal Y1, ByVal X2, ByVal Y2)
        '' 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, DatabaseServices.OpenMode.ForRead)


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

            '' Create a line
            Dim acLine As Line = New Line(New Point3d(X1, Y1, 0), New Point3d(X2, Y2, 0))

            acLine.SetDatabaseDefaults()

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

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