[vtkusers] vtkRenderWindow contents to ppm

[Dean Inglis]

Hi,

RenderWindows used to be able to do this:

  iren->SetUserMethod(&fn,(void*)renWin);

void fn(void *ren)
{
 ((vtkWin32OpenGLRenderWindow *)ren)->SetFileName("scrdump.ppm");
 ((vtkWin32OpenGLRenderWindow *)ren)->SaveImageAsPPM();
}

which now is in vtkImageWindow.  How can I do this with a 3D image from a
vtkRenderWindow?

Dean