Creating an extruded solid using an arbitrary polygon as its base

By Balaji Ramamoorthy

Solids in AutoCAD can be created using primitive shapes such as Box, Cone etc or by performing operations such as Extrude, Sweep etc.

Here is a sample code to demonstrate the creation of a solid by extruding a region.

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Public Sub CreateSolidMethod()
    Dim db As Database = 
        Application.DocumentManager.MdiActiveDocument.Database
 
    'start a transaction
    Using tr As Transaction = 
                        db.TransactionManager.StartTransaction()
 
        ' create 5 lines to make the region from
        Dim l1, l2, l3, l4, l5 As Line
        l1 = New Line(
                        New Point3d(0, 0, 0),
                        New Point3d(4, 0, 0)
                     )
 
        l2 = New Line(
                        New Point3d(4, 0, 0),
                        New Point3d(4, 6, 0)
                     )
 
        l3 = New Line(
                        New Point3d(4, 6, 0),
                        New Point3d(0, 6, 0)
                     )
 
        l4 = New Line(
                        New Point3d(0, 6, 0), 
                        New Point3d(-2, 3, 0)
                     )
 
        l5 = New Line(
                        New Point3d(-2, 3, 0),
                        New Point3d(0, 0, 0)
                     )
 
        ' add the lines to the array
        Dim myArray As New DBObjectCollection()
        myArray.Add(l1)
        myArray.Add(l2)
        myArray.Add(l3)
        myArray.Add(l4)
        myArray.Add(l5)
 
        ' create the region
        Dim myRegion As New Region()
        Dim myRegions As New DBObjectCollection()
        myRegions = myRegion.CreateFromCurves(myArray)
        myRegion = myRegions(0)
 
        ' create the solid
        Dim my3DSolid As New Solid3d()
        my3DSolid.Extrude(myRegion, 10.0, 0.0)
 
        Dim bt As BlockTable 
                = CType(
                        tr.GetObject(
                                        db.BlockTableId, 
                                        OpenMode.ForRead, 
                                        False
                                     )
                                     , BlockTable
                        )
        Dim btr As BlockTableRecord 
                = CType(
                        tr.GetObject(
                            bt(BlockTableRecord.ModelSpace),
                            OpenMode.ForWrite, 
                            False
                            ), 
                            BlockTableRecord
                        )
 
        'add 3DSolid to the model space block table record
        btr.AppendEntity(my3DSolid)
 
        'Let the transaction know about this object
        tr.AddNewlyCreatedDBObject(my3DSolid, True)
 
        tr.Commit()
    End Using
End Sub