You have probably exceeded the hardware exceleration capabilities of your
video card (my max is 1024 x 768 if I'm carefull with buffer sizes,
particularly the depth buffer). Check your hardware specifications for the
amount of video memory you're carrying. A quich check would be to run the
program at a lower resolution (say 1024 x 768 w/ 24 bit color) and see if
your fps rate drops as dramatically. At full screen 1152 x 864 w/ 32 bit
color with a 16 bit depth buffer requires ~6 M of video memory not counting
any memory requirements for textures and display lists. At some point your
system will quit using video memory and try to do everything in main memory
causing a dramatic slowdown.
Hope this helps....
> I've just set up a new system (PII 400 w. ELSA 16MB TNT) an installed
> Opengl 1.1, which includes the demo program skyfly. I ran that, and it
> look decent in a small window (approx. 35 fps when flying between land and
> sky) but when I maximized the window to 1152x864 (32-bit colour), the
> frame rate dropped to <7fps. I realize the frame rate should drop, but
> this is far below what I expected. Is this normal, or have I missed
> something? Any advice would be appreciated.