让你的微小离子随机分布更均匀--布朗运动

    1、布朗运动揭秘http://baike.baidu.com/view/17875.htm
    2、在动画制作过程中到处都能看到随机的应用，然而我们直接通过随机数生成的随机数并不是很均匀，当我们想让物体感觉没有外力、任何意识均匀分布时（如：浩瀚的星空，盒子里乱飞的蜜蜂苍蝇，太阳光照射的灰尘等等），布朗运动就相当管用了。
    3、基本原理：
         3.1方形分布(舞台中心上下方各100像素)：
    for(var i:uint=0;i<numCircle;i++) { circle = new UCircle(); circle.x = stage.StageWidth/2 + Math.random() * 100 - 50; circle.y = stage.StageHeight/2 +Math.random() * 100 - 50; myCirclePanel.addChild(circle); circles.push(circle); }
         3.2:圆形分布:
    for(var i:uint=0;i<numCircle;i++) { circle = new UCircle(); var radius:Number = Math.sqrt(Math.radom()) * maxRadius; var angle:Number = Math.random() * (Math.PI * 2); circle.x = stage.StageWidth/2 + Math.cos(angle) * radius; circle.y = stage.StageHeight/2 + Math.sin(angle) * radius; myCirclePanel.addChild(circle); circles.push(circle); }
    3.3:偏向分布(趋于中心分布，越靠近中心越多):
   for(var i:uint=0;i<numCircle;i++) { circle = new UCircle(); xpos = 0; ypos = 0; for(var j:uint = 0;j<iterations ;j++) //六次迭代偏向均匀分布 { xpos += Math.random() * stage.stageWidth; ypos += Math.random() * stage.stageHeight; } circle.x = xpos / iterations; circle.y = ypos / iterations; myCirclePanel.addChild(circle); circles.push(circle); }
    4、综合应用(绘制了300个闪烁的小萤火虫子在盒子中飞舞):
    package { import flash.display.Sprite; import flash.events.Event; public class BrownClass extends Sprite { //myMask //myMolecule private var numCircle:uint = 300; private var iterations:uint = 6; private var circles:Array; public function BrownClass() { init(); } public function init():void { var circle:UCircle; circles = new Array(); var xpos:Number ; var ypos:Number; for(var i:uint=0;i<numCircle;i++) { circle = new UCircle(); xpos = 0; ypos = 0; for(var j:uint = 0;j<iterations ;j++) //六次迭代偏向均匀分布 { xpos += Math.random() * stage.stageWidth; ypos += Math.random() * stage.stageHeight; } circle.x = xpos / iterations; circle.y = ypos / iterations; myCirclePanel.addChild(circle); circles.push(circle); } this.addEventListener(Event.ENTER_FRAME,onEnterframe); } function onEnterframe(e:Event):void { var circle:UCircle; for(var i:uint=0;i<numCircle;i++) { circle = circles[i]; circle.x += Math.random() * 0.8 - 0.4; circle.y += Math.random() * 0.8 - 0.4; //将圆点局限在盒子内运动 if(circle.x<myMask.x) { circle.x=myMask.x } else if(circle.x>(myMask.x + myMask.width - circle.width)) { circle.x = myMask.x + myMask.width - circle.width; } if(circle.y<myMask.y) { circle.y=myMask.y } else if (circle.y>(myMask.y + myMask.height - circle.height)) { circle.y= myMask.y + myMask.height - circle.height; } } } } }
5、DEMO演示及源代码:http://www.flash8.net/fla/10071.shtmlhttp://www.flash8.net/fla/10071.shtml