Hi all, I am trying to set up a FPS max in OpenGL. In the main message loop of my WinMain function, I have this : while(not done) { get a message; process a message; if(screen is not minimized) render; } I think this is causing my program to eat 100% CPU all the time. So I want to instate a max FPS and change the loop to this : while(not done) { get a message; process a message; if(screen is not minimized) { checkFPS; if(FPS < maxFPS) render; else SYSTEM CALL TO IDLE } } So, what I want to know is : what system call does Windows provide that allows me to return control of the CPU so that I am not using 100% CPU all the time. Lets say my program is getting 200 FPS @ 100% CPU, and I want to instate a max of 80 FPS, then I want to be using 40%CPU @ 80 FPS. Is this possible? Cheers, -Tim

You can probably use the Sleep function... You pass the number of milliseconds you want to stay idle, as a parameter

if(FPS < maxFPS)

Doing this is a bad idea. It will cause skipping, especially if the system renders to the max FPS very quickly. With that method, the system will stop rendering all of a sudden, causing NO updates. So lets say I have some super computer that can render 60 frames in 0.2 seconds. Now, for the next 0.8 seconds, the scene will NOT be updated, it''ll look frozen.

What I would do is find the amount of time, in miliseconds, that should be allocated for each frame. Lets say you want to have a target framerate of 60 fps. You would divide 1 by 60 and get 0.016 ms. You would then check in your render loop, using a timer, to see if the time elapsed from the last render is greater than the interval, and if so, render the scene.

Thanks for the replies...

I modifed my code per Hawkeye''s suggestion.

As for the Sleep call, I applied Hawkeye''s suggestion and my CPU usage has dropped to 1% (without Sleep). If CPU becomes a problem again, I will try the Sleep call.

Cheers

-agentsim