[vtkusers] offscreen rendering bug ?

[John Shalf]

alext at win.tue.nl wrote:

>   Hi,
>
>   I've just downloaded the vtkOpenGlOffscreenRenderWindow written by John
> Shalf (code at: http://www.ncsa.uiuc.edu/~heiland/vtk/vtkOffScreen.tar.gz).
> This seems to be the only portable manner I can render something offscreen
> under UNIX - for Windows, there's a similar class included already in vtk's
> contrib ditectory.

>   However it seems to me that vtkOpenGlOffscreenRenderWindow has a few bugs.
> Namely, I can't manage to use it without Pbuffers _and_ with volume
> rendering actors. I don't get anything rendered offscreen. As soon as I
> switch to Pbuffers (I'm on an O2), all works fine, I get my offscreen
> rendering of the volumes.

Whoops,
I'm looking at the code.  The QueryConfig and QueryPBuffer() methods should not have been
enabled if it is compiled without -DPBUFFER.  It looks like I need to do some code
synchronization here.  I'm stuck with a flakey wireless network on the SC2k showfloor right
now.  But Randy is here too and we'll try to work something out before we leave (or at least
hammer out a plan to get the code all sync'ed up again).

Another issue that comes up is that you *MUST* disable the display lists or you will end up
with really weird looking stuff in your renderwindow.  display lists do not work at all with
offscreen rendering (unless you use Mesa to do offscreen rendering, but in that case they are
rather superfluous)

>   Anyone knowing about this problem ? Anyone knowing how to render
> volumes/geometries offscreen under X (besides the Mesa solution, I'm using
> OpenGL and not the Mesa library).

Sorry about the bugs.... they are hurting someone else on this list too.  We'll get everything
back to working order soon.

-john