Using vtkPicker with Python/Vtk

[David Gobbi]

Hi Vetle,

The line in your code which is at fault is

renderWidget.__ActorPicker = new_picker

This doesn't work because __ActorPicker is a private attribute.
In python, this is true of any attribute that starts with '__'.
Unfortunately, trying to set a private attribute in Python doesn't 
raise an exception.

What you should do instead is edit vtkRenderWidget.py and add
the following two methods:

    def SetPicker(self,picker):
        self.__ActorPicker = picker

    def GetPicker(self):
        return self.__ActorPicker

I'll try to get these changes into the nightly releases, as well.

 - David

--
  David Gobbi, MSc                    dgobbi at irus.rri.on.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

On Sun, 9 Jan 2000, Vetle Roeim wrote:

> I'm trying to use vtkPicker and its associated sub-classes in a project,
> using Python and vtkRenderWidget.
> This is not described in "Vtk User's Guide", but I understand that
> vtkRenderWidget is rather new, so it is understandable.
> 
> On page 62 of the User's Guide, it says how to use vtkPicker with
> vtkRenderWindowInteractor. Although it is possible to use
> vtkRenderWindowInteractor in Python, it is not possible to do so if you
> wish to use the renderwindow as a Tk widget (I experienced strange
> behaviour when I tried this).
> 
> Fortunately, vtkRenderWidget implements most of the
> vtkRenderWindowInteractor's functionality, but it seems to dislike
> picking.
> 
> There does not exist a "SetPicker()" method in vtkRenderWidget, so I tried
> setting the picker explicitly, like this:
>     picker = vtkCellPicker()
>     picker.SetPickMethod( foo )
>     renderWidget.__ActorPicker = new_picker
> 
> It does not work as expected. 'foo' is a function that prints a string to
> standard output. Here is the complete script I used to test the feature:
> 
>     #!/usr/bin/env python
> 
>     import Tkinter
>     from VTK import *
> 
>     root = Tkinter.Tk()
> 
>     ren = vtkRenderer()
>     renderWidget = vtkTkRenderWidget( root )
>     renderWidget.pack()
>     renWin = renderWidget.GetRenderWindow()
>     renWin.AddRenderer( ren )
> 
>     def foo():
>         print 'foobar'
> 
>     picker = vtkCellPicker()
>     picker.SetPickMethod( foo )
>     renderWidget.__ActorPicker = picker
> 
>     coneSource = vtkConeSource()
>     coneMapper = vtkPolyDataMapper()
>     coneMapper.SetInput( coneSource.GetOutput() )
>     coneActor = vtkActor()
>     coneActor.SetMapper( coneMapper )
> 
>     ren.AddActor( coneActor )
>     picker.AddPickList( coneActor )
> 
>     root.mainloop()
> 
> So, my question is; how should I do this? How is it possible to use
> picking together with vtkRenderWidget?
> 
> 
> 
> Thanks,
> Vetle Roeim
> Student at Department of Informatics, University of Oslo, Norway
> 
> 
> 
> 
> -----------------------------------------------------------------------------
> This is the private VTK discussion list.  Please keep messages on-topic.
> Check the FAQ at: <http://www.automatrix.com/cgi-bin/vtkfaq>
> To UNSUBSCRIBE, send message body containing "unsubscribe vtkusers" to
> <majordomo at gsao.med.ge.com>.  For help, send message body containing
> "info vtkusers" to the same address.     Live long and prosper.
> -----------------------------------------------------------------------------
> 




-----------------------------------------------------------------------------
This is the private VTK discussion list.  Please keep messages on-topic.
Check the FAQ at: <http://www.automatrix.com/cgi-bin/vtkfaq>
To UNSUBSCRIBE, send message body containing "unsubscribe vtkusers" to
<majordomo at gsao.med.ge.com>.  For help, send message body containing
"info vtkusers" to the same address.     Live long and prosper.
-----------------------------------------------------------------------------