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Question
I am writing a .NET plug-in that extends RhinoScript. I've used the information on this page to get started:
http://en.wiki.mcneel.com/default.aspx/McNeel/SdkExtendRhinoScript.html
I would like to write a function in .NET, that I could call from RhinoScript, that I could pass an array of 3-D point coordinates, manipulate these coordinates, and then pass the modified values back to RhinoScript. I am not sure how to proceed. Any help would be appreciated.
Answer
The stumbling block here is that when a SafeArray passed from VBScript, it is marshalled as a .NET object. Thus, you must cast the object to a .NET Array.
The following example code demonstrates how you can do this.
VB.NET
Public Function TweakPoints(ByVal var As Object) As Object
' Default return value
TweakPoints = Nothing
' The safearray passed from VBScript is marshalled as a .NET object.
' So, try to cast the object argument as an array.
Dim arr As Array = TryCast(var, Array)
If arr Is Nothing Then Exit Function
' Declare our results array
Dim rc As New ArrayList()
' Loop through all point arrays
Dim i As Integer = 0
For i = 0 To UBound(arr)
' The safearray passed from VBScript is marshalled as a .NET object.
' So, try to cast the object argument as an array.
Dim pt As Array = TryCast(arr.GetValue(i), Array)
If (pt IsNot Nothing) AndAlso (pt.Length = 3) Then
' Extract the point coordinate values
Dim x As Double = Convert.ToDouble(pt.GetValue(0))
Dim y As Double = Convert.ToDouble(pt.GetValue(1))
Dim z As Double = Convert.ToDouble(pt.GetValue(2))
'
' TODO: do some kind of point manipulation here....
'
' Declare an array for the new point
Dim point As New ArrayList()
' Add the updated coordinates to the array
point.Add(x)
point.Add(y)
point.Add(z)
' Add the array to the results array as an object
rc.Add(point.ToArray())
End If
Next
' Return our results array
TweakPoints = rc.ToArray()
End Function