Pixel Swarm

@author Michael Svendsen

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lines:145
license : see code comments
modified : 2009-07-25 23:32:08

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package {
	import flash.display.Bitmap;
	import flash.display.BitmapData;
	import flash.display.Shape;
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.filters.BlurFilter;
	import flash.geom.Point;

/**
	 * @author Michael Svendsen
	 */
	public class PixelSwarm_001 extends Sprite {
		
		private  var   _w:Number;
		private  var   _h:Number;
		private  var   _bmd:BitmapData;
		
		private  var   _swarmData:Vector.<Object>;
		private  var   _leader:Object;
		
		private  var   _swarmAmount:Number;
		private  var   _leaderTime:Number;
		
		private  var   _leaderSpeed:Number;
		private  var   _leaderRotSpeed:Number;
		private  var   _leaderRunTime:Number;
		
		private  var   _swarmTwitch:Number;
		private  var   _swarmSpeed:Number;
		private  var   _swarmRotSpeed:Number;
		
		public function PixelSwarm_001():void{
			addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
		}
		
		private function onAddedToStage(e:Event):void{
			
			_w = stage.stageWidth;
			_h = stage.stageHeight;
			
			_bmd = new BitmapData(_w, _h, false, 0xFFFFFF);
			addChild(new Bitmap(_bmd));
			
			initSwarm();
			
		}
		
		private function initSwarm():void{
			
			_leaderTime = 0;
			_swarmAmount = 25;
			
			_leaderRotSpeed = 20;
			_leaderSpeed = 10;
			_leaderRunTime = 30;
			
			//follower values
			_swarmTwitch = 40;
			_swarmRotSpeed = 10;
			_swarmSpeed = 10;
			
			_createSwarm();
			
		}
		
		private function _createSwarm():void{
			
			_leader = [];
			_leader.x = _w  * 0.5;//Math.floor( Math.random() * _w);
			_leader.y = _h  * 0.5;//Math.floor( Math.random() * _h);
			_leader.rotation = 0;
			_leader.rotSpeed = 20;
			_leader.speed = 30;
			_leader.runTime = 30;
			_leader.goalX = 0;
			_leader.goalY = 0;
			_leader.goalAngle = 0;
			
			_swarmData = new Vector.<Object>();
			var i:int = 0;
			var max : int = _swarmAmount;
			for(i; i<max; i++){
				
				var f:Object = new Object();
				f.x = _w  * 0.5;//Math.floor( Math.random() * _w);
				f.y = _h  * 0.5;//Math.floor( Math.random() * _h);
				f.rotation = 0;
				f.rotSpeed = _swarmRotSpeed;
				f.twitch = _swarmTwitch;
				f.speed = _swarmSpeed;
				f.goalX = 0;
				f.goalY = 0;
				f.goalAngle = 0;
				
				_swarmData.push(f);
			}
			
			stage.addEventListener(Event.ENTER_FRAME, onStageEnterFrame);
			
		}
		
		private function onStageEnterFrame(e:Event):void{
			
			moveSwarm();
			drawSwarm();
			
		}
		
		private function moveSwarm():void{
			
			if(_leaderTime == 0){
				
				_leader.goalX = Math.floor( Math.random() * _w);
				_leader.goalY = Math.floor( Math.random() * _h);
				_leaderTime = _leader.runTime;
				
			}
			
			_leader.goalAngle = Math.atan2( _leader.goalY - _leader.y, _leader.goalX - _leader.x );
			_leader.goalAngle = _leader.goalAngle * 180 / Math.PI;
			_leader.goalAngle = angleFix(_leader.goalAngle - _leader.rotation);
			
			if(_leader.goalAngle < 180){
				_leader.rotation += _leader.rotSpeed;
			} else {
				_leader.rotation -= _leader.rotSpeed;
			}
			
			_leader.x += calcCos(_leader.rotation) * _leader.rotSpeed;
			_leader.y += calcSin(_leader.rotation) * _leader.rotSpeed;
			
			_leaderTime --;
			
			var i:int = 0;
			var max : int = _swarmAmount;
			for(i=0; i<max; ++i){
				
				var follower:Object = _swarmData[i];
				
				follower.goalX = _leader.x;
				follower.goalY = _leader.y;
		
				follower.goalAngle = Math.atan2(follower.goalY-follower.y, follower.goalX-follower.x);
				follower.goalAngle = follower.goalAngle*180/Math.PI;
				follower.goalAngle = angleFix(follower.goalAngle-follower.rotation);
		
				if (follower.goalAngle<180) {
					follower.rotation += follower.rotSpeed;
				} else {
					follower.rotation -= follower.rotSpeed;
				}
				
				follower.rotation += Math.floor(Math.random() * follower.twitch) - Math.floor(follower.twitch*0.5);
		
				follower.x += calcCos(follower.rotation)*follower.speed;
				follower.y += calcSin(follower.rotation)*follower.speed;
				
			}
			
			
		}
		
		private function drawSwarm():void{

var s:Shape = new Shape();
			s.graphics.beginFill(0xFFFFFF, 0.2);
			s.graphics.drawRect(0, 0, _w, _h);
			s.graphics.endFill();

_bmd.draw(s);
			_bmd.applyFilter(_bmd, stage.getRect(this), new Point(), new BlurFilter(5,5,1));
			
			_bmd.setPixel(_leader.x, _leader.y, 0xFF0000);
			
			var i:int = 0;
			var max : int = _swarmAmount;
			while(i<max){
				
				var f:Object = _swarmData[i];
				_bmd.setPixel(f.x, f.y, 0x000000);
				
				i++;
				
			}
			
		}
		
		private function calcCos(pAngle:Number):Number{
			return Math.cos( pAngle * Math.PI/180);
		}
		
		private function calcSin(pAngle:Number):Number{
			return Math.sin(pAngle * Math.PI/180);
		}
		
		private function angleFix(pAngle:Number):Number{
		
			if(pAngle > 360){
				pAngle = pAngle%360;
			}
			
			while(pAngle < 0) {
				pAngle += 360;
			}
			
			return pAngle;
		}
		
		
		
	}
}

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