基於egret的攝像機類管理器的實現

egret做爲一個HTML5的遊戲引擎竟然連基本的攝像機都沒有，讓我這個作遊戲開發的十分不習慣，因而本身動手去作了一個相似於攝像機的一個類
原理大概是這樣的：建立一個容器 利用這個容器放大縮小來模擬攝像機的zoom 能夠動態修改錨點改變攝像機的觀察位置 移動整個場景來模擬攝像機的移動 廢話很少說 直接上代碼：

module com.controller{
    //鏡頭管理類 用來移動 拉伸鏡頭
    export class CameraManager extends egret.DisplayObjectContainer{
        //目標容器
        private targetObject:any;
        //單例
        static _instance:CameraManager;
        //攝像機的移動速度
        private speed:number    = 10;
        //上一個容器的X位置
        private lastTargetX:number = 0;
        //上一個容器的Y位置
        private lastTargetY:number = 0;

        /**
         * @status
         * STAY 中止
         * MOVEDOWN  向下移動
         * MOVEUP    向上移動
         * MOVELEFT  向左移動
         * MOVERIGHT 向右移動
         * */

        private status:string = "STAY";

        /**
         * 總共須要的移動距離x
         * */
        private distanceX:number = 0;
        /**
         * 總共須要的移動距離y
         * */
        private distanceY:number = 0;

        /**
         *移動距離x
         **/
        private moveX:number = 0;

        /**
         * 移動距離y
         **/
        private moveY:number = 0;
        //構造函數
        constructor(){
            super();
            this.addEventListener(egret.Event.ENTER_FRAME,this.onEnterFrame,this)
        }
        setAt(target){
            this.targetObject = target;
        }
        //聚焦到某一個物體的錨點上
        lookAt(target:any){
            //this.lastTargetX = target.x;
            //this.lastTargetY = target.y;
            AnchorUtil.setAnchorX(this.targetObject, target.x/this.targetObject.width);
            AnchorUtil.setAnchorY(this.targetObject, target.y/this.targetObject.height);
            this.targetObject.x =  this.targetObject.x+(target.x-this.lastTargetX)*com.model.DataCenter.instance.configVO.whRate;
            this.targetObject.y =  this.targetObject.y+(target.y-this.lastTargetY)*com.model.DataCenter.instance.configVO.whRate;
            this.lastTargetX = target.x;
            this.lastTargetY = target.y;
        }
        //放大或者縮小
        zoom(pix){
            egret.Tween.get(this.targetObject).to({scaleX:pix,scaleY:pix},300,egret.Ease.sineIn).to({scaleX:1,scaleY:1},300,egret.Ease.sineIn);
        }
        //向某個方向必定距離
        moveTo(distance:number,status:string){
            this.status = status;
            switch (status){
                case "MOVEDOWN":
                    this.distanceY = distance;
                    break;
                case "MOVELEFT":
                    this.distanceX = distance;
                    break;
                case "MOVEUP":
                    this.distanceY = distance;
                    break;
                case "MOVERIGHT":
                    this.distanceX = distance;
                    break;
            }
        }
        //tween到某個位置
        private onEnterFrame(e:egret.TouchEvent){
            switch (this.status){
                case "STAY":
                    this.moveY = 0;
                    this.distanceY = 0;
                    this.moveX = 0;
                    this.distanceX = 0;
                    break;
                case "MOVEUP":
                    this.targetObject.y += this.speed;
                    this.moveY+=this.speed;
                    if(this.moveY>=this.distanceY){
                        this.status = "STAY";
                    }
                    this.targetObject.x += 0;
                    break;
                case "MOVEDOWN":
                    this.targetObject.y -= this.speed;
                    this.moveY+=this.speed;
                    if(this.moveY>=this.distanceY){
                        this.status = "STAY";
                    }
                    this.targetObject.x += 0;
                    break;
                case "MOVERIGHT":
                    this.targetObject.x -= this.speed;
                    this.moveX+=this.speed;
                    if(this.moveX>=this.distanceX){
                        this.status = "STAY";
                    }
                    this.targetObject.y += 0;
                    break;
                case "MOVELEFT":
                    this.targetObject.x += this.speed;
                    this.targetObject.y += 0;
                    this.moveX+=this.speed;
                    if(this.moveX>=this.distanceX){
                        this.status = "STAY";
                    }
                    break;
            }
        }
        static  get instance():CameraManager{
            if(this._instance==null){
                this._instance = new CameraManager()

            }
            return this._instance;
        }
    }
}