Steiner Chain 03

...
@author 9re

by 9re 17 Jun 2009

Tags

fractal シュタイナーの円鎖
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/**
 * Copyright 9re ( http://wonderfl.net/user/9re )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/aCI8
 */

package 
{
	import flash.display.MovieClip;
	import flash.display.Sprite;
	import flash.events.Event;
	
	/**
	 * ...
	 * @author 9re
	 */
	[SWF(backgroundColor="#000000", frameRate="29")]
	public class DocumentClass extends MovieClip
	{
		private var _scale:Number = 20;
		private var _n:int = 12;
		private var _cx:Number;
		private var _cy:Number;
		private var _circles:Array = [];
		private var _t:Number = 0;
		private var _a:Number;
		private var _rho:Number;
		private var _r:Number;
		private var X:Number = 0.1;
		private var Y:Number = -0.2;
		
		public function DocumentClass() 
		{
			var r:Number = 0.7;
			_a = Math.PI / _n;
			_rho = r * Math.sin(_a) / (1 - Math.sin(_a));
			_a = 2 * _a;
			var s:Number;
			
			_r = r + _rho;
			
			_cx = stage.stageWidth / 2;
			_cy = stage.stageHeight / 2;
			
			
			
			var sp:Sprite;
			for (var i:int = 0; i < _n; ++i) 
			{
				sp = new Sprite();
				sp.graphics.beginFill(0xffffff, (i + 1) / _n);
				sp.graphics.drawCircle(0, 0, _rho * _scale);
				sp.graphics.endFill();
				addChild(sp);
				_circles.push(sp);
			}
			
			addEventListener(Event.ENTER_FRAME, enterFrameHandler);
		}
		
		private function enterFrameHandler(e:Event):void 
		{
			var sp:Sprite;
			var t:Number;
			for (var i:int = 0; i < _n; i++) 
			{
				t = _t + i * _a;
				sp = _circles[i];
				placeCircle(sp, X + _r * Math.cos(t), Y + _r * Math.sin(t), _rho);
			}
			
			_t += Math.PI / 30;
		}
		
		private function placeCircle($circle:Sprite, cx:Number, cy:Number, cr:Number):void {
			var c:Number = cx * cx + cy * cy - cr * cr;
			var rx:Number, ry:Number, rr:Number;
			$circle.x = cx / c * _scale + _cx;
			$circle.y = -cy / c * _scale + _cy;
			$circle.scaleX = $circle.scaleY = cr / c / _rho;
		}
		
		public function draw(cx:Number, cy:Number, cr:Number):void {
			var c:Number = cx * cx + cy * cy - cr * cr;
			var rx:Number, ry:Number, rr:Number;
			rx = cx / c * _scale + _cx;
			ry = -cy / c * _scale + _cy;
			rr = cr / c * _scale;
			
			graphics.drawCircle(rx, ry, rr);
		}
		
	}
	
}