limiting FPS

OpenGL Development
#1

there is a way for limit FPS ( to somthing like 50 ~ 60 FPS) for free some CPU (example : for network thread or gc) ?

#2

I think the only way to limit FPS is to use Thread.sleep()…

#3

This snatch of code from Alien Flux is what I use:


                        if (!GL.WGL_EXT_swap_control) {
                              float elapsed = 0.0f;
                              frameTime = 0.0f;
                              do {
                                    long now = Sys.getTime();
                                    elapsed = (float)(now - then) / (float)Sys.getTimerResolution();
                                    if (frameTime == 0.0f)
                                          frameTime = elapsed;
                                    if (elapsed < FRAME_TIME)
                                          Thread.sleep(1);
                              } while (elapsed < FRAME_TIME);
                              gl.swapBuffers();
                        } else {
                              long now = Sys.getTime();
                              frameTime = (float)(now - then) / (float)Sys.getTimerResolution();
                              gl.swapBuffers();
                        }

If it can’t get WGL_EXT_swap_control I’ve found that doing loads of tiny sleeps is lighter on the CPU than a processor-hogging busy loop. Especially as I run at high priority.

Cas :slight_smile:

#4

trying that
BTW :
FRAME_TIME , got an advise on this value ?

what is the ‘then’ variable in your code ?

#5 


/** How many frames per second we want */
public static final int DESIRED_FPS = 60;

/** The duration of one frame, in seconds */
public static final float FRAME_TIME = 1.0f / (float) DESIRED_FPS;

...

                        long then = Sys.getTime();

                        // Do drawing here

                        // Then cap frame rate as above here

Cas :slight_smile:

#6

Thanks ! it works very well ;D

no more GC lags cause there is plenty free CPU times :slight_smile:

btw about GC :
java -server -Xms512m -Xmx512m -XX:NewSize=64m -XX:MaxNewSize=64m -XX:SurvivorRatio=2 -XX:+UseConcMarkSweepGC

I tryed to use new 1.4.1 GC, it’s really nice, reduce the GC lag effect

for reference: http://wireless.java.sun.com/midp/articles/garbagecollection2/#4.3