[osg-users] Modern OpenGL and VBO performance

[Gedalia Pasternak]

Just as a follow up, I tried the vao support in the top of master and was
unable to get it to work with a simple openflight terrain.
I've opened an issue with the info here:
https://github.com/openscenegraph/OpenSceneGraph/issues/165
long story short when I hooked up glDebugOutput it crashed in a glDraw
function after the driver sent the following warning
message = GL_INVALID_OPERATION error generated. Invalid VAO/VBO/pointer
usage.
Anyone else have it working?
-gedalia


On Wed, Nov 9, 2016 at 12:53 PM, Gedalia Pasternak <gpasternak at mak.com>
wrote:

> 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
>
>


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