弹簧链

package cn.d
{
    import flash.display.Sprite;
    import flash.display.StageAlign;
    import flash.display.StageScaleMode;
    import flash.events.Event;

    public class Spring5 extends Sprite
    {
        private var ball:Ball;
        private var spring:Number=0.1;
        private var vx:Number=0;
        private var vy:Number=0;
        private var friction:Number=0.6;
        private var gravity:Number=5;

        private var balls:Array=[];

        public function Spring5()
        {
            stage.scaleMode=StageScaleMode.NO_SCALE;
            stage.align=StageAlign.TOP_LEFT;
            
            init();
        }

        private function init():void
        {
            
            for (var i:int=0; i < 10; i++)
            {
                ball=new Ball();
                balls.push(ball);
                addChild(ball);
            }
            
            addEventListener(Event.ENTER_FRAME, onEnterFrame);
        }

        private function onEnterFrame(event:Event):void
        {

            graphics.clear();
            
            graphics.lineStyle(1);
            
            graphics.moveTo(mouseX, mouseY);
            moveBall(balls[0], mouseX, mouseY);
            graphics.lineTo(balls[0].x, balls[0].y);

            for (var i:int=1; i < 10; i++)
            {
                var b1:Ball=balls[i];
                var b2:Ball=balls[i - 1];

                moveBall(b1, b2.x, b2.y);
                graphics.lineTo(b1.x, b1.y);
            }

        }

        private function moveBall(ba:Ball, targetX:Number, targetY:Number):void
        {

            ba.vx+=(targetX - ba.x)*spring;
            ba.vy+=(targetY - ba.y)*spring;

            ba.vy+=gravity;

            ba.vx*=friction;
            ba.vy*=friction;

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

        }
    }
}