Re: pfMultithread -- PFPROC_CULL

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Bernard Leclerc (bleclerc++at++poster.cae.ca)
Thu, 20 Mar 1997 10:10:09 -0500

Thomas M. Miller wrote:

> >From man page:
>
> "When multithreading the CULL, care must be taken to avoid data collisions
> in user callback functions. In particular, pfChannel and pfNode CULL
> callbacks (pfChanTravFunc, pfNodeTravFuncs) may be invoked in parallel."
>
> I have a scene in which all of the geosets have indexed geostates if I change
> the geostate table for each channel would it adversely affect the scene
> when multithreading?
>
> Is each cull thread capable of holding its own geostate table?

Thomas,

The geostate table set through pfChannel::setGStateTable() is private to the
channel and will be handled properly by the CULL stage even when multithreading.
What the man page is telling you is to pay attention to data shared by callbacks -
especially if those callbacks are setting node attributes. For instance if the CULL
callback associated with a light source calls pfLightSource::on() or ::off(), this
will certainly affect the other channel being culled in parallel.

-- 
Bernard Leclerc, Technical Leader, 3-D Graphics Applications
CAE Electronics Ltd. (http://www.cae.ca)
8585 Cote De Liesse, Saint-Laurent, Quebec, Canada, H4L-4X4
tel: +1 514 341 2000 extension 2275, fax: +1 514 340 5496
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