[osg-users] VBOs not actually used?

Paul Melis paul at science.uva.nl
Thu Mar 12 07:32:59 PDT 2009


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.


PS glxinfo reports GL_ARB_vertex_buffer_object is supported, OpenGL 
version is 2.1.0 NVIDIA 96.43.01
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