package  
{
	import flash.display.Sprite;
	import flash.events.MouseEvent;
	import flash.events.SampleDataEvent;
	import flash.media.Sound;
	import flash.utils.setTimeout;

	/**
	 * <PLUGGED STRING>
	 * 
	 * Very simple Karplus-Strong example for FFK09 '10 Hot Minutes' in cologne.
	 * 
	 * An advancement, more guitar-like implementation can be found here:
	 * http://lab.andre-michelle.com/karplus-strong-guitar
	 * 
	 * @author Andre Michelle
	 */
	[SWF(width='320',height='240',frameRate='255',backgroundColor='0xFFFFFF')]
	public class KarplusStrong extends Sprite 
	{
		private const NUM_SAMPLES: int = 3072; // 3072 seems the best numSamples to provide with respect to performance and low latency
		
		private var _sound: Sound;
		
		private var _periodN: int;
		private var _period: Vector.<Number>;
		private var _periodIndex: int;
		
		private var _current: Number;
		
		private var _feedNoise: Boolean;
		
		public function KarplusStrong()
		{
			_periodN = 44100 / 220; // length = sampleRate / targetFrequency (ignoring fractional)
			_period = new Vector.<Number>( _periodN, true );
			_periodIndex = 0;
			
			_feedNoise = true;
			_current = 0.0;
			
			_sound = new Sound();
			_sound.addEventListener( SampleDataEvent.SAMPLE_DATA, sampleData );
			
			stage.addEventListener( MouseEvent.MOUSE_DOWN, function ( event: MouseEvent ): void { _feedNoise = true; } );
			
			setTimeout( _sound.play, 500 ); // delay start to avoid glitches
		}
		
		private function sampleData(event: SampleDataEvent): void
		{
			for( var i: int = 0 ; i < NUM_SAMPLES ; ++i )
			{
				if( _periodIndex == _periodN ) // wrap around delay-line
				{
					_periodIndex = 0;
					_feedNoise = false;
				}
				
				if( _feedNoise )
				{
					_period[ _periodIndex ] += Math.random() - Math.random(); // feed noise between -1 and +1
				}
				
				_current += ( _period[ _periodIndex ] - _current ) * .5; // 1 pole lowpass (removing energie from the system)
				
				_period[ _periodIndex ] = _current; // write feedback
				
				// write amplitude to event > output
				event.data.writeFloat( _current );
				event.data.writeFloat( _current );
				
				++_periodIndex;
			}
		}
	}
}