Create a MPolygon in AutoCAD using .NET

By Augusto Goncalves

MPolygon is a custom object created for AutoCAD Map 3D, but is also available in vanilla AutoCAD from ObjectARX. To use it from .NET, then the project need to reference the AcMPolygonMGD.dll and it is required to load the object enabler AcMPolygonObj19.dbx into AutoCAD prior to using MPolygon functions. Both files can be found in AutoCAD’s install folder.

Imports Autodesk.AutoCAD.Runtime    Imports Autodesk.AutoCAD.DatabaseServices    Imports Autodesk.AutoCAD.ApplicationServices    Imports Autodesk.AutoCAD.Geometry         Public Class MPolygonCommandClass      ' to make sure the required DBX is loaded      ' let's implement the extension application      ' and load it on Initilize      Implements IExtensionApplication           Public Sub Initialize() _        Implements IExtensionApplication.Initialize        ' Make sure that AcMPolygonObj19.dbx is loaded for MPolygon        ' the 19 version number is valid for AutoCAD 2013        Autodesk.AutoCAD.Runtime. _          SystemObjects.DynamicLinker.LoadModule( _            "AcMPolygonObj19.dbx", False, False)      End Sub           Public Sub Terminate() _        Implements IExtensionApplication.Terminate        ' nothing is required for this sample      End Sub            _      Public Sub CreateMPolygon()        Dim db As Database = Application. _          DocumentManager.MdiActiveDocument.Database        Using transaction As Transaction = _          db.TransactionManager.StartTransaction()          Try            ' open the block tabela and the model space            Dim bt As BlockTable = transaction.GetObject( _              db.BlockTableId, OpenMode.ForRead)            Dim btr As BlockTableRecord = transaction.GetObject( _              bt(BlockTableRecord.ModelSpace), _              OpenMode.ForWrite)                 ' start creating the MPolygon            ' by its loop            Dim mPolygonLoop As MPolygonLoop            mPolygonLoop = New MPolygonLoop()            mPolygonLoop.Add(New BulgeVertex(New Point2d(2, 2), 0))            mPolygonLoop.Add(New BulgeVertex(New Point2d(2, 1), 0))            mPolygonLoop.Add(New BulgeVertex(New Point2d(1, 1), 0))            mPolygonLoop.Add(New BulgeVertex(New Point2d(1, 2), 0))            mPolygonLoop.Add(New BulgeVertex(New Point2d(2, 2), 0))                 ' finally create the entity and append            ' the the model space 
            Dim mPolygon As MPolygon = New MPolygon()            mPolygon.AppendMPolygonLoop(mPolygonLoop, False, 0)            btr.AppendEntity(mPolygon)            transaction.AddNewlyCreatedDBObject(mPolygon, True)            transaction.Commit()          Catch ex As Exception            Debug.WriteLine(ex.ErrorStatus)            Debug.WriteLine(ex.Message)          End Try        End Using      End Sub    End Class