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_MaB_
09-29-2010, 01:54 AM
I have used transform feedback to store results of some computationally more demanding shaders and draw them in later updates. It works fine on my desktop Quadro FX 3800, but doesn't on my notebook GeForce 9300M. Problem seems to be related to glDrawTransformFeedback call, because when I replace this call by corresponding glDrawArrays, everything work as it should. Also the GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN query returns correct value and buffer object contains valid data. So it seems to me like some driver issue with glDrawTransformFeedback. (Maybe the number of primitives to be drawn is not correctly set???)

Here are configurations of my computers:

1) desktop (working)

Suse 11.2 x86_64, X.Org version: 1.6.5, NVidia driver 256.53
some glGetStrings:
Renderer: Quadro FX 3800/PCI/SSE2
Version: 3.3.0 NVIDIA 256.53
Shading language version: 3.30 NVIDIA via Cg compiler

2) notebook (not working):
Suse 11.3 x86_64, X.Org version: 1.8.0, NVidia driver 256.53
some glGetStrings:
Renderer: GeForce 9300M GS/PCI/SSE2
Version: 3.3.0 NVIDIA 256.53
Shading language version: 3.30 NVIDIA via Cg compiler

If it will be usefull, I can post relevant fragments of sources too.

Thanks for any advice.

mhagain
09-29-2010, 03:38 AM
Feedback is a deprecated feature. See also: http://www.opengl.org/wiki/Common_Mistakes#Selection_and_Picking_and_Feedback _Mode

It's quite possible that your app will run faster without feedback anyway.

somboon
09-29-2010, 03:58 AM
I think he mean "Transform feedback" not the old "Feedback mode".

_MaB_
09-29-2010, 04:46 AM
Yes, I really meant Transform Feedback - functions like glGenTransformFeedbacks, glBeginTransformFeedback, glDrawTransformFeedback etc.

Is it the right place to post this, or should I write to some NVidia forum? Does anyone have some experiences with reporting such problems?

mfort
09-29-2010, 09:18 AM
My experience is that NVIDIA people (Piers Daniell, Barthold Lichtenbelt) monitor this forum. But there is no guarantee.

Filling NVIDIA bug report doesn't hurt.