Drawing a cone - parameter meanings

[laurie.comerford]

Hi,

When using VB.NET to draw a cone, the auto cues ask for:

cosineangle as double   - what is this?

sinangle as double    - what is this?

baseorigin as Point3D  - obvious

base radius as double  - obvious

axis of symetry as vector3D   - what is this?

reference axis as vector3D   - what is this?

height as Autodesk.AutoCAD.Geometry.Interval

- obvious

startangle as double

end angle as double. - presumably this and the start angle allow segments of a cone to be drawn, so I would try 0 and two pi

Searching this NG and Google does not return any clues as to the actual realities of the pararmeters I've questioned.

 Assumming I have all the transaction code in place is the following code like to function to draw a unit height cone at 0,0,0?

        Dim dHeight As Autodesk.AutoCAD.Geometry.Interval = 1
        Dim dCosineAngle As Double = 1  ' Guess this as Cos(0)
        Dim dSineAngle As Double = 0   ' Guess this as Sin(0)
        Dim CenterPoint As New Geometry.Point3d(0, 0, 0)
        Dim dBaseRadius As Double = 0.5
        Dim AxisOfSyymetry As New Vector3d(0, 0, 1)  ' Guess this as the Z axis
        Dim ReferenceAxis As New Vector3d(1, 0, 0)  ' Guess this as the X axi
        Dim myCone As New Cone(dCosineAngle, dSineAngle, CenterPoint, dBaseRadius, AxisOfSyymetry, ReferenceAxis, dHeight, 0, 2 * Math.PI)
        myTrans.AddNewlyCreatedDBObject(myCone, True)

[Alfred.NESWADBA]

Hi Laurie,

not that I'm knowing each of these parameters, I have more a global question that may put you away from what you are doing currently.

The question is: are you trying to create a Geometry.Cone to get it placed into the database? IMHO that will not work, you should start with "new DatabaseServices.Solid" and create the cone with revolve or extrude (as shown >>>here<<< by Kean Walmsley).

At least this statement:

myTrans.AddNewlyCreatedDBObject(myCone, True)

will not work as long as the cone is a type defined in the Geometry-namespace.

- alfred -

[laurie.comerford · Accepted solution]

Hi Alfred,

Thank you and Ken.  While I can learn from my mistakes, it's so much easier when someone points out where the mistake lies. 

I put Ken's C# code through:

http://www.developerfusion.com/tools/convert/csharp-to-vb/

and checked it successfully.

My need for a cone is very simple and I've modified Ken's code as shown below to show how I'll normally use it:

   '' This is the typical way I will use the DrawCone Sub, but there are more options allowed for
    <CommandMethod("TDC")> _
    Sub TestDrawCone()
        Dim Pt2D As New Point2d(0, 0)
        DrawCone(Pt2D)
    End Sub


    Public Sub DrawCone(ByVal InsertionPoint As Point2d, _
                                   Optional ByVal dpHeight As Double = 1, _
                                   Optional ByVal dpRadius As Double = 0.05, _
                                   Optional ByVal dpTopRadius As Double = 0, _
                                   Optional ByVal spLayerName As String = "0")

        Dim doc As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim db As Database = doc.Database
        Dim ed As Editor = doc.Editor
        Dim bCreateHistory As Boolean = True
        Dim Pt3D As New Point3d(0, 0, dpHeight / 2)
        Dim dTopRadius As Double = 0

        Dim tr As Transaction = db.TransactionManager.StartTransaction()
        Using tr
            ' Create the solid and set the history flag
            Dim oSolid As New Solid3d()
            oSolid.RecordHistory = bCreateHistory
            oSolid.CreateFrustum(dpHeight, dpRadius, dpRadius, dpTopRadius)
            oSolid.Layer = spLayerName
            ' Add the Solid3d to the modelspace
            Dim bt As BlockTable = DirectCast(tr.GetObject(db.BlockTableId, OpenMode.ForRead), BlockTable)
            Dim ms As BlockTableRecord = DirectCast(tr.GetObject(bt(BlockTableRecord.ModelSpace), OpenMode.ForWrite), BlockTableRecord)
            ms.AppendEntity(oSolid)
            tr.AddNewlyCreatedDBObject(oSolid, True)
            ' And transform it to the selected point
            oSolid.TransformBy(Matrix3d.Displacement(Pt3D - Point3d.Origin))
            tr.Commit()
        End Using
    End Sub ' DrawCone