forked from: 100,000 Particles Screw Effect

@author Lee
@see http://webnoon.net/entry/플레시-Actionscript-30-10만개-파티클-테스트-mouseX의-비용-체험

by hacker_4x9ig2v4 10 Apr 2010

• Forked from jidolstar's 100,000 Particles Screw Effect
• Diff: 5
• Related works: 78

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effect particles
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// forked from jidolstar's 100,000 Particles Screw Effect 
// forked from jidolstar's 10만개 입자를 이용한 유체 시뮬레이션 실험 
// forked from nulldesign's Liquid10000
package {
	import flash.display.Bitmap;
	import flash.display.BitmapData;
	import flash.display.Sprite;
	import flash.display.StageAlign;
	import flash.display.StageScaleMode;
	import flash.events.Event;
	import flash.events.MouseEvent;
	import flash.geom.ColorTransform;

	import net.hires.debug.Stats;

	/**
	 * @author Lee
	 * @see http://webnoon.net/entry/플레시-Actionscript-30-10만개-파티클-테스트-mouseX의-비용-체험
	 */
	[SWF(width="365", height="365", backgroundColor="0x000000")];
	public class bitmap_screw extends Sprite {
		private var _positions:Vector.<Particle>;
		private var _bmd:BitmapData;
		private var _len:int=10000
		private var _colT:ColorTransform;

		public function bitmap_screw() {

			stage.scaleMode=StageScaleMode.NO_SCALE;
			stage.align=StageAlign.TOP_LEFT;
			stage.frameRate=100;

			_positions=new Vector.<Particle>();
			var i:int;
			for (i=0; i < _len; i++) {
				var pt:Particle=new Particle(stage.stageWidth * Math.random(), stage.stageHeight * Math.random());
				_positions.push(pt);
			}

			for (i=0; i < _len - 1; i++) {
				_positions[i].next=_positions[i + 1];
			}

			_colT=new ColorTransform(.9, .9, .8);

			_bmd=new BitmapData(stage.stageWidth, stage.stageHeight, false, 0);
			addChild(new Bitmap(_bmd));

			addEventListener(Event.ENTER_FRAME, loop);
			stage.addEventListener(MouseEvent.CLICK, ch);

			addChild(new Stats());
		}

		private function ch(event:MouseEvent):void {
			var pt:Particle=_positions[0];
			while (pt.next) {
				pt.x=stage.stageWidth * Math.random();
				pt.y=stage.stageHeight * Math.random();
				pt=pt.next;
			}
		}

		private function loop(event:Event):void {

			var pt:Particle=_positions[0];
			var mx:Number, my:Number;
			mx=mouseX;
			my=mouseY;

			_bmd.lock();
			_bmd.colorTransform(_bmd.rect, _colT);
			while (pt.next) {

				//perp 벡터 구해서 force 등록
				var dx:Number=pt.x - mx;
				var dy:Number=pt.y - my;
				//var dx : Number = pt.x - mouseX; //이런식으로 하면 느려서 안된다.
				//var dy : Number = pt.y - mouseY;

				var perpX:Number=-dy;
				var perpY:Number=dx;

				var f:Number=18.0 / (dx * dx + dy * dy);
				perpX*=f;
				perpY*=f;
				dx*=-f;
				dy*=-f;

				pt.vx+=dx + perpX;
				pt.vy+=dy + perpY;

				pt.x+=pt.vx;
				pt.y+=pt.vy;

				pt.vx*=.9;
				pt.vy*=.9;

				_bmd.setPixel(pt.x, pt.y, 0xffffff);
				pt=pt.next;
			}
			_bmd.unlock();
		}
	}
}

final class Particle {
	public var next:Particle;

	public var x:Number, y:Number, vx:Number, vy:Number, ax:Number, ay:Number;


	public function Particle($x:Number, $y:Number) {

		x=$x;
		y=$y;
		vx=vy=ax=ay=0.0;
	}
}