[osg-users] VBOs not actually used?

Paul Melis paul at science.uva.nl
Thu Mar 12 07:53:03 PDT 2009


Thrall, Bryan wrote:
> Paul Melis wrote on Thursday, March 12, 2009 9:33 AM:
>
>   
>> Hi,
>>
>> While trying to debug a collegue's code that uses a dynamically
>>     
> updated
>   
>> color array on a Geometry that uses VBOs I'm getting confused about
>>     
> VBO
>   
>> support in OSG 2.8.
>> Given the attached simple .osg file (a single colored quad, flagged to
>> not use display lists, but to use VBOs) I can see with an OpenGL
>>     
> tracer
>   
>> (bugle) that no VBO is actually used on my nvidia FX5200 system. The
>> quad is simply drawn using glVertex() and friends. Are there
>>     
> limitations
>   
>> to when VBOs can be used? And, if so, is there a way to have OSG
>>     
> loudly
>   
>> complain when a request for VBOs can not be satisfied?
>>
>> Similarly, the attached c++ test case is more in line with our
>>     
> original
>   
>> code. It uses a color array that is updated each frame. The array is
>> flagged as dirty with a call to dirty(), but here also, no VBOs seem
>>     
> to
>   
>> get used.
>>
>> Regards,
>> Paul
>>
>> PS glxinfo reports GL_ARB_vertex_buffer_object is supported, OpenGL
>> version is 2.1.0 NVIDIA 96.43.01
>>     
>
> Binding PER_PRIMITIVE forces OSG out of fast path rendering, so I don't
> think it can use VBOs. Using OVERALL or PER_VERTEX instead allowed VBOs
> on my system.
>   
DANG! That's it, thanks...

Paul




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