skybox making slower?

[martinzwigl]

hi folks

i have a terrain with apx. 50.000 triangles. and with a fov of 35 and some frustum culling a get a fps-rate of 80.

now i put a skybox around it (actually a cylinder with apx 100 polys) and my fps-rate drops down to 40. no "additional" function calls no pop and push just two cos and sin-functions (yes, these are function calls).

is it possible that just those math-functions can reduce the speed that much.

curios,
martin

[CoBour]

If you have enabled Vertical Sync, then this happens. Your Programm would run at let's say 75 fps with sync disabled, but in your case it has to wait for the next retrace, so it can only run at 80, 40, 20, 10 fps and so on. Just disable Vertican Sync in your display driver. Hope this is clear enough.

Regards
CoBour

[Michael Steinberg]

Another point might be that the engine is fillrate limited...

[zed]

no its not possible that using those 2 functions will result in any (practicle) speed difference , as michael saiz its likely that the skybox is using a lot of fillrate as they normally cover the whole screen, perhaps this couple with vsync can result in such a framerate drop

[martinzwigl]

Thank for the help guys

i have heard about fillrate. i am just using a window 800x600, and when i make the window smaller there is still no increase.
i'll go and see what vsync does.

thanks for the suggestions,
martin