how to lock my game at 30 fps

You can make a hi-res timer with 1.4.2 using the "hidden" class sun.misc.Perfpublic class HiResTimer() {

Perf hiResTimer;

long freq;

public HiResTimer() {

hiResTimer = Perf.getPerf();

freq = hiResTimer.highResFrequency();

}

public long currentTimeMillis() {

return hiResTimer.highResCounter() * 1000 / freq;

}

}

jboeinga at 2007-7-15 3:25:21 >

Recipee for constant frame rate if you are using threads:

If you are using threads and you will work at a constant frame rate you have first to calculate the time a frame should remain on screen in milliseconds: delayPerFrame = 1000/frameRate.

You have to use the thread's function .sleep(x) and x is delayPerframe - time_you_use_to_draw_frame_stuff.

Of course this time will change while execution, therefore you need a timer. Java's timer is not precise enough for this purpose and the resolution of System.getTimeMillis() is also not high enough. So you have to write a timer on your own.

Idea:

Use a separate Thread with an infinite loop where a long-counter is increased and the thread sleeps for 1 millisecond.

Code:

Public class PreciseTimer implements Runnable{

private Thread preciseTimerThread = new Thread(this, "precise");

private long milliSeconds=0;

private boolean endTimer = false;

public PreciseTimer()

{

preciseTimerThread.start();

}

public void start(){

milliSeconds=0;

}

public long getMilliSeconds(){

if (milliSeconds>maxMilliSeconds){milliSeconds=maxMilliSeconds;}

return (milliSeconds);

}

public void endTimer(){

endTimer=true;

}

public void run(){

while (!endTimer){

milliSeconds+=1;

try{preciseTimerThread.sleep(1);}catch(java.lang.InterruptedException e){}

}

}

}

in your drawing thread you put:

PreciseTimer preciseTimer = new PreciseTimer();

//main loop begins

{

preciseTimer.start()

//draw frame...

try{

'thisthread'.sleep(delayPerFrame-preciseTimer.getMilliSeconds ())

catch(..)...

}

//main loop ends

preciseTimer.endTimer();

You should also check that for sleep(x), x remains positive.

I also used this method in my java game resulting in a constant frame rate. The precise timer-thread will not really affect the performance.

Good luck!

exxiona at 2007-7-15 3:25:21 >