[osg-users] Modern OpenGL and VBO performance

[Gedalia Pasternak]

Hello list,

    I'm wondering if anyone has done performance testing on the new VAO
support in 3.6? I'm using 3.4 and see a significant performance hit when
turning on the GL3 flags and using VBO's, As a test I restored call list
support and saw a significant performance improvement vs the VBO path. But
still slower then the non gl3 pipeline. ( Some of these settings are
embedded in the saved ive file which makes it a bit harder to test
different code paths.) But OSG seems to be enabling and disabling lots of
VBO attributes and doesn't particularly draw stuff in a way that's
optimized to have the minimal number of attribute changes.

I've also added a Material UBO which seems a reasonable replacement for the
existing attribute which uses deprecated functionality. But it's not clear
how to do this cleanly. And would need that UBO to be added to all shaders.
It's still unclear to me how enabling gl3 should work. Shader generation
doesn't automatically happen and there's really very little rendering out
of the box.
Gedalia

-- 
DI-Guy Engineering Lead, VT MÄK
150 Cambridge Park Drive, 3rd Floor, Cambridge, MA 02140
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