Alternative to NSTimer - Printable Version

Code:

float target = 1000 / 60.0f;

float frameAverage = target;

long lastFrame = System.currentTimeMillis();

float yield = 10000f;

float damping = 0.1f;

        

while (running)

{

    long timeNow = System.currentTimeMillis();

    frameAverage = (frameAverage * 10 + (timeNow - lastFrame)) / 11;

    lastFrame = timeNow;

            

    yield += yield*((target/frameAverage)-1)*damping+0.05f;

    for(int i = 0; i < yield; i++)

    {

        Thread.yield();

    }



    update();

    draw();

}

Code:

// Runs the main loop. This will keep going as long as running is YES.

// Fires as fast as it possibly can, giving a delta that is based upon the

// fraction of the target FPS we're getting.

- (void) mainLoop

{

    //Get the resolution of the iPhone timer.

    mach_timebase_info_data_t timerInfo;

    mach_timebase_info(&timerInfo);

    

    //Store the ratio between the numberator and the denominator.

    const float TIMER_RATIO = ((float)timerInfo.numer / (float)timerInfo.denom);

    

    //The resolution of the iPhone is in nanoseconds.

    const uint64_t RESOLUTION = 1000000000;

    

    //Create a target time variable based upon the iPhone timer resolution and our FPS.

    const float TARGET_TIME = (float)RESOLUTION / [Globals getTargetFPS];

    

    //Start the frame average at the target time for a frame.

    float frameAverage = TARGET_TIME;

    

    //Create an artificial last update time that matches our target delta.

    lastUpdateTime = mach_absolute_time() * TIMER_RATIO - TARGET_TIME;

    

    //It will act this many times before it draws.

    const unsigned int DRAW_FREQUENCY = 3;

    unsigned int timesUpdated = 0;

    

    //Start the game loop.

    while (running)

    {

        //Create the autorelease pool.

        NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

        

        //Get the current time and convert it to a useable standard value (ns).

        uint64_t now = mach_absolute_time() * TIMER_RATIO;

        

        //Adjust the frame average based upon how long this last update took us.

        frameAverage = (frameAverage * 10 + (now - lastUpdateTime)) / 11;

        

        //Create a delta out of the value for the current frame average.

        float delta = frameAverage / TARGET_TIME;

        

        //Set the last delta so we can access it elsewhere.

        [Globals setLastDelta:delta];

        

        //Refresh the last update time.

        lastUpdateTime = now;

        

        //Yield to system calls (touches, etc.) for one ms.

        while( CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.002, FALSE) == kCFRunLoopRunHandledSource);

        

        //Update the game logic.

        [model update:delta];

        

        //Draw the game.

        timesUpdated++;

        if (timesUpdated >= DRAW_FREQUENCY)

        {

            [glView drawView];

            timesUpdated = 0;

        }

        

        [pool release];

    }

}