package {
	import animation.trigonometry.ArrowByLoad;
	import flash.display.Sprite;
	import flash.events.Event;

	/**
	 * @author Maliu
	 */
	[SWF(frameRate = 30)]	//这里的元数据标签要Flex SDK才支持，Flash IDE不支持
	public class EaseToMouse extends Sprite
	{
		private var arrow:ArrowByLoad;	//鼠标跟随的元件，外部载入
		private var easing:Number = 0.5; //缓动值，决定跟随速度的快慢，可自己尝试修改该值以观察效果
		private var vx:Number = 0;	//x轴速度
		private var vy:Number = 0;	//y轴速度
		private var angle:Number;	//角度，由dy与dx得到
		private var dx:Number;	//目标与当前元件的x轴距离
		private var dy:Number;	//目标与当前元件的y轴距离
		
		private var arrowArray : Array;	//储存跟随对象的数组
		private const numArrow:Number = 10;	//跟随对象的数目
		private const scaleValue:Number = 0.86;	//基础缩放值
		
		public function EaseToMouse()
		{
			init();
		}
		//初始化
		private function init():void
		{
			arrowArray = new Array();
			for(var i:int = 0; i<numArrow; i++)
			{
				arrow = new ArrowByLoad();
				addChild(arrow);
				arrowArray.push(arrow);
			}
			this.addEventListener(Event.ENTER_FRAME, onEnterFrame);
			arrow.addEventListener(Event.COMPLETE, setScale); //侦听加载事件的完成，解决异步引起的不能缩小元件的问题
		}
		private function onEnterFrame(e:Event):void
		{
			for(var i:int = 0; i<numArrow; i++)
			{
				//因为数组里不包含鼠标的坐标，因此分开判断进行不同的传值
				if(i > 0)
				{
					calEvery(arrowArray[i-1].x, arrowArray[i-1].y, arrowArray[i]);
				}
				else
				{
					calEvery(mouseX, mouseY, arrowArray[i]);
				}
			}
		}
		//计算传入currentArrow的rotation，需要传入dx和dy
		private function calRotation(currentArrow:ArrowByLoad, dx:Number, dy:Number):void
		{
			angle = Math.atan2(dy, dx);
			currentArrow.rotation = angle * 180/Math.PI;
		}
		//计算每个元件的缓动，传入不同的目标值和缓动对象
		private function calEvery(targetX:Number, targetY:Number, currentArrow:ArrowByLoad):void
		{
			dx = targetX - currentArrow.x;
			dy = targetY - currentArrow.y;
			if(Math.abs(dx)<1 && Math.abs(dy)<1)
			{
				vx = 0;
				vy = 0;
				//currentArrow.x = targetX;
				//currentArrow.y = targetY;
			}
			else
			{
				vx = dx * easing;
				vy = dy * easing;
				calRotation(currentArrow, dx, dy);
				//currentArrow.x += vx;
				//currentArrow.y += vy;
			}
			currentArrow.x += vx;
			currentArrow.y += vy;
		}
		//给每个元件赋予不同的缩放值和透明度
		private function setScale(e:Event):void
		{
			var n:Number = this.numChildren;
			var tempScale:Number = 0;
			var temp:ArrowByLoad;
			for(var i:int = 0; i<n; i++)
			{
				temp = arrowArray[i];
				tempScale = Math.pow(scaleValue, i);
				temp.scaleX = tempScale;
				temp.scaleY = tempScale;
				temp.alpha = tempScale;
			}
		}
	}
}