[Paraview] How to invalidate data

[Fabian Wein]

Hi David,

> Sorry Fabian, I've been quite busy at Vis and haven't been able to help.
I can understand! For my tight deadline we skipped paraview and
implemented a
simple standalone live-data-visualization tody in Qt for a
presentation next week
- hence I'm not under pressure any more.

But I will need to solve the issue in Paraview later, more relaxed :)

I finally came to such a scenario as you described - I just don't know
(yet)
how to implement it.

In python it seems to be a bad idea as paraview is not responding
while the python
shell is running (even when it waits most of the time on sleep()).

At least from python I also did not find, how to call
RequestInformation() and
RequestUpdateExtent() from my vtkAlgorithm based reader. Do you know?

You ment this methods by "standard information property", right?

Writing a reader is not that complicated and most probably all a user
needs
to implement in general.
But a "live-data aware animation" needs some kind of GUI (start,
pause, stop),
propably it might even allow concurrent user interactions like zooming.
I guess this is rather difficult to implement as plugin?!

Indeed I think it would be best to have an enhanced Animation feature
that does
not only request as fast as possible but polls RequestInformation(),
RequestUpdateExtent().

I believe such an extension would make performing live-data/
realtime-vis/ in-situ
as requested by some users much easier to implement (by just making
the readers sensitive)
but without handling the full VTK pipeline.

I just submitted a feature request: 9724

Thanks for any help/ comments,

Fabian

> Warning, I did this back in the 2.6/3.0 timeframe.
> The animation has changed since then, as has data information
> gathering, so the same path may not still work.
> 
> It looks like in the simplest path for live data in paraview it would:
>  have the client periodically poll the reader via a standard
> information property
>  that property calls a function on the server's root node that:
>    makes the vtk reader safely check for new data (simplest way is to
> look for new file N, then update to N-1)
>    update the temporal range/timesteps information
>    call modified on itself to make the lazy VTK pipeline flow far enough
>  an answer of "there is new data, max time is now t" would mark the
> live reader's source proxy as modified and...
>  when in an auto accept mode automatically set the application's time
> to t and call StillRender on the active view