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Robert Osfield wrote:
> Hi Tim,
>
> On Nov 26, 2007 1:10 PM, Tim Moore <[EMAIL PROTECTED]> wrote:
>> In revision 7017, which introduced the ability to compile OpenGL buffers
>> using pbuffers,
>> it looks like you make GL object compilation happen in the pager thread if
>> the pbuffers
>> aren't available, and you override the checks for available time and maximum
>> objects with
>> compileAllGLObjects(). It would seem that these two things would guarantee
>> dropped frames
>> when paging in scenes that have large individual requests. Am I missing
>> something, or is
>> it vastly preferred to do the object compilation in pbuffers? I've only
>> played with that
>> a little, but wouldn't seem to be very useful unless you have more than two
>> processors.
>
> You must be misreading the code, compilation of OpenGL objects can
> never happen from within the paging thread - it doesn't have a
> graphics context to do such a thing, the compilation is either done by
> any the threads running pbuffers that are available or the graphics
> threads drawing the actual graphics windows themselves. If one
> attempted to compile from within the paging thread then the app would
> crash.
That's what I thought, but starting on line 673 in DatabasePager.cpp, in the
run function:
if (gc)
{
osg::GraphicsThread* gt = gc->getGraphicsThread();
if (gt)
{
gt->add(new
DatabasePager::CompileOperation(this));
}
else
{
gc->makeCurrent();
compileAllGLObjects(*(gc->getState()));
gc->releaseContext();
}
}
>
> As for preference of pbuffers, we'll its not selected by default so
> there isn't a preference for it in terms of the OSG. In your own app
> you may find pbuffer and associated graphics threads are effective,
> this will depend upon the hardware you have, the quality of the OpenGL
> drives (and their ability to handle multi-threaded usage) and the
> nature of your models.
>
> In general paged databases with lots of geometry and textures to load
> per tile load will work better with a back ground compile context (
> pbuffer and associated thread) if you have the CPU resouces to support
> it.
>
> Robert.
>
> Robert.
> _______________________________________________
> osg-users mailing list
> osg-users@lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
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