[sldev] UDP Receiver: GL error: Invalid Operation

Tofu Linden tofu at lindenlab.com
Thu Dec 10 09:17:15 PST 2009


Personally I'd recommend only making GL calls from a single thread -
otherwise you'll have to do a lot of locking or keep two utterly
separated GL contexts.

I don't totally understand what you're trying to achieve though -
it's not obvious to me why your media code would have to perform
actual GL calls (usually you'd hand your media buffer over to the
app and the app itself does the GL rendering).

I admit I'm also fuzzy on what the 'Hippo Viewer' is based upon; I'd
recommend working from a recent Snowglobe tree where the media system is
rather different (better - safer and more extensible, I hope) than our
legacy one.

VAN BROECK Sigurd wrote:
> We've been using the Quicktime library of the Hippo Viewer to get media
> streams into SL. Since we need more control over the streams, we
> implemented a simple UDP receiver that's in coding identical to the
> llmediaimplquicktime (except for the Quicktime library calls of course)
> and that works just fine. The media packets are arriving over UDP and
> can be displayed using the OpenCV library. However, as soon as we access
> the GL functions from the UDP receiver thread, we get GL error 'invalid
> operation'.
> 
> Debugging learns that we access the GL functions inbetween glBegin() and
> glEnd() being called probably by the existing Hippo rendering thread(s).
> Question is then of course how we can avoid making calls at the wrong
> time. We don't really see how the Quicktime library accomplishes that.
> Is there somewhere a synchronization mechanism that we must use?
> 
> Thanks for helping out,
> Sigurd
> 
> 
> 
> 
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