[osg-users] frame rate locking, gpu stalling problem

Alberto Luaces aluaces at udc.es
Mon Oct 8 01:06:48 PDT 2007


El Sunday 07 October 2007 03:09:55 idontgot aname escribió:
> It seems that as I zoom in/out, the framerate stays
> locked at a certain range until it can't handle it
> anymore. 60fps zoomed out, down to 30fps, down to
> 20/15/10 etc. and the gpu time goes up because of
> this.
>
> Does anyone know why the framerate would stay fixed at
> those ranges?

Hi,

this is a matter of synchronization with the screen refresh. Note that  
20/15/10 fps are divisors of 60. If you are rendering at 60 fps and you draw 
the frame too late, you have to wait for the next refresh, so your framerate 
will go down to 30 fps. If you draw slower, the frame have to wait until the 
next refresh signal, so the framerate will drop to 20, then 10, then 6... 
until 1/0 fps.

For experimental purposes only, you can deactivate the vertical 
synchronization in your driver options and see how these ranges disappear. 
Note that this is not recommended because it lessens the image quality 
(tearing artifacts may appear).

Alberto



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