[vtkusers] vtkWindowToImageFilter and vtkImageViewer

[Jonathan M. Gilligan]

WindowToImageFilter does not behave like a regular filter. Specifically, since 
a window does not maintain a modification timestamp, the filter does not know 
when it needs to update.

Essentially, WindowToImageFilter takes a snapshot of a window when you first 
SetInput and the snapshot is not updated unless you explicitly call 
WindowToImageFilter::Modified(). The solution, then is to insert calls to

    wtif Modified

and

    wtif_sub Modified

at approproate times.

Hope this helps. I got pretty confused by this myself a few weeks ago and 
wasted a lot of time until I found an answer in the old vtk mailing list 
archives.

Regards,
Jonathan

>===== Original Message From Wolfram H Volpi <whv88240 at Bayou.UH.EDU> =====
>Please help me find why the viewer displays all black.
>I suspect I a doing something wrong with vtkWindowToImageFilter.

Jonathan M. Gilligan                  jonathan.gilligan at vanderbilt.edu
The Robert T. Lagemann Assistant Professor       Office:  615-343-6252
                   of Living State Physics       Lab (FEL)    343-7580
Dept. of Physics and Astronomy                   Fax:         343-7263
6823 Stevenson Center
Vanderbilt University, Nashville TN 37235        Dep't Office 322-2828