ISOMetric

public class QuartzEngine extends MovieClip
	{
    	public static var FPS:Number = 62;		
		protected static var quartzTimer:Timer;
 
		// Time Calculation Variables
    	private var _period:Number = 1000 / FPS;
		private var _beforeTime:int = 0;
		private var _afterTime:int = 0;
		private var _timeDiff:int = 0;
		private var _sleepTime:int = 0;
		private var _overSleepTime:int = 0;
		private var _excess:int = 0;
 
		public function QuartzEngine():void
		{			
			addEventListener(Event.ADDED_TO_STAGE, onAdded);
		}
 
		/*
		 * On added to stage Event, starts preloader
		 * @Event
		 */
		protected function onAdded(evt:Event):void
		{
			if(!quartzTimer) {
				quartzTimer = new Timer(1);
				quartzTimer.addEventListener(TimerEvent.TIMER, onQuartzEvent);		
				quartzTimer.start();
			}
 
			stop();		
		}
 
		/**
		 * Pauses the timer rendering
		 */
		protected function pause():void
		{
			quartzTimer.stop();
		}
 
		/**
		 * Starts the timer rendering
		 */
		protected function start():void
		{
			quartzTimer.start();
		}		
 
		private function onQuartzEvent(evt:TimerEvent):void
		{
           	_beforeTime = getTimer();
            _overSleepTime = (_beforeTime - _afterTime) - _sleepTime;
 
			// LOGIC HERE =============================
 
			render()
 
			// LOGIC END ==============================
 
			_afterTime = getTimer();
            _timeDiff = _afterTime - _beforeTime;
            _sleepTime = (_period - _timeDiff) - _overSleepTime;        
            if (_sleepTime <= 0) {
                _excess -= _sleepTime;
                _sleepTime = 2;
            }       
            quartzTimer.reset();
            quartzTimer.delay = _sleepTime;
            quartzTimer.start();
 
			while (_excess > _period) {
				// Execute required commands if slept for too long
				// For debugging
				//render()
 
				_excess -= _period;
            }
		}
 
		protected function render():void
		{
			if(stage) {
				stage.dispatchEvent(new MWEvent(MWEvent.RENDER));
			}
		}