游戏中的镜头

游戏中的镜头。锁定对象，根据计算坐标，修改父容器坐标，让物品处于最中点。

package
{
	import flash.display.Sprite;
	import flash.display.Stage;
	import flash.events.Event;
	import flash.filters.GlowFilter;
	import flash.geom.Point;

	/**
	 *  @author:Gaara
	 *  2012-3-16
	 *
	 **/
	public class Camer extends Sprite
	{
		private var myStage:Stage;
		private var target:Sprite;
		
		public function Camer(stage:Stage)
		{
			addChild(ResConfig.myLpBmp);
			this.myStage = stage;
			this.addEventListener(Event.ENTER_FRAME,onEnterFrame);
		}
		
		/**
		 *  功能:
		 *  参数:
		 **/
		public function lockAt(target:Sprite):void
		{
			if(this.target != null){
				this.target.filters = [];
			}
			this.target = target;
			target.filters = [new GlowFilter(0x00FF00)];
		}
		
		protected function onEnterFrame(event:Event):void
		{
			if(this.target != null){
				var spriteCP:Point = globalToLocal(new Point(stage.stageWidth/2,stage.stageHeight/2));
				
				var decX:Number = target.x -  spriteCP.x;
				var decY:Number = target.y - spriteCP.y ;
				x -= decX;
				y -= decY;
			}
		}
	}
}