Performance Problem (help!)


I am very new to OpenGL, so I’m hoping someone wull be able to give me some ideas on the following problem.

I am basically trying two render two objects. The first is a textured quad which I am using as a background image. The second is an instrument guage.

When I render the background image alone, its take less than a millisecond. When I render the guage alone its takes about 30ms. However when I render both i.e the background followed by the guage on top the rendering time jumps up to over 200ms per frame !

Obviuosly there must be some interaction between the textured quad and the gauge, but I can’t figure out what happening. I though it might be related to blending so I disabled that, but it made no difference.

My platform is windows. I’ve tried running some OpenGL bench marks on my machine which have far more complex objects and they are achieving 100fps.

Any ideas ?



Can you be more precise or show code about how you draw your objects ?

As wild guess it may ba a problem with texturing : do you respecify each texture at each frame when drawing 2 objects ? Instead use glBindTexture. Do you rebuild displaylists each frame ? Do not.


Thanks for the advice. I am using glbindTexture already so the problem is not here. I’ll need to see if I can simplify the code a little and then I’ll post an example.