[LayaAirIDE 2.0]Laya多点触控是有开关吗 为什么多点触控没有任何反应

目前要实现的功能是通过加载的.lh模型文件 进行手指多点触控之后实现缩放及其旋转   根据官方的引擎示例制作后在手机中触控没有任何反应
想问一下是有开关吗  还是我写的不对  下面是代码及其截图  请明白的给指点一下 谢谢    链接就是官方示例  根据示例所做
import GameConfig from "./GameConfig";
import ui from "./ui/layaMaxUI";
class Main {
    constructor(){
        //初始化引擎
        Laya3D.init(0, 0);
        Laya.stage.scaleMode = Laya.Stage.SCALE_FULL;
        Laya.stage.screenMode = Laya.Stage.SCREEN_NONE;
        this.upVector3 = new Laya.Vector3(0, 1, 0);
        //预加载所有资源
        let resource = ["Export/LayaScene_JJF/Conventional/JJF.lh"];
        Laya.loader.create(resource, Laya.Handler.create(this, this.onComplete));
    }
    onComplete(){
        //创建场景
        let scene = Laya.stage.addChild(new Laya.Scene3D());
        //创建相机
        let camera = scene.addChild(new Laya.Camera(0, 0.1, 100));
        //设置相机的名称
        camera.name = "camera";
        //相机平移位置
        camera.transform.translate(new Laya.Vector3(0, 0.8, 1.5));
        //旋转相机
        camera.transform.rotate(new Laya.Vector3(-15, 0, 0), true, false);
            
        //创建平行光
        let directionLight = scene.addChild(new Laya.DirectionLight());
        //设置平行光颜色
        directionLight.color = new Laya.Vector3(0.6, 0.6, 0.6);
            
        //加载小猴子精灵
        let monkey = Laya.Loader.getRes("Export/LayaScene_JJF/Conventional/JJF.lh");
        //猴子精灵添加组件（脚本）
        monkey.addComponent(MonkeyScript);
        scene.addChild(monkey);
        //设置相机的观察目标为小猴子
        camera.transform.lookAt(monkey.transform.position, new Laya.Vector3(0, 1, 0));
            
        //显示文本显示框
        this.text = new Laya.Text();
        this.text.x = Laya.stage.width / 2 -50 ;
        this.text.text = "触控点归零";
        //显示文本显示框
        this.text = new Laya.Text();
        this.text.name = "ceshi";
        this.text.overflow = Laya.Text.HIDDEN;
        this.text.color = "#FFFFFF";
        this.text.font = "Impact";
        this.text.fontSize = 20;
        this.text.borderColor = "#FFFF00";
        this.text.x = Laya.stage.width / 2;
        Laya.stage.addChild(this.text);
}
}
//激活启动类
new Main();
class MonkeyScript extends Laya.Script3D{
    constructor(){
        super();
        this.scene = null;
        this.text = null;
        this.camera = null;
        this.lastPosition = new Laya.Vector2(0, 0);
        this.distance = 0.0;
        this.disVector1 = new Laya.Vector2(0, 0);
        this.disVector2 = new Laya.Vector2(0, 0);
        this.isTwoTouch = false;
        this.first = true;
        this.twoFirst = true;
        this.rotate = new Laya.Vector3(0,0,0);
        this.translate = new Laya.Vector3(0,0,0);
    }
    onStart(){
        this.scene = this.owner.parent;
        this.text = this.scene.parent.getChildByName("ceshi");
        this.camera = this.scene.getChildByName("camera");
    }
    onUpdate(){
        let touchCount = this.scene.input.touchCount();
        if (1 === touchCount){
            //判断是否为两指触控，撤去一根手指后引发的touchCount===1
            if(this.isTwoTouch){
                return;
            }
            this.text.text = "触控点为1";
            //获取当前的触控点，数量为1
            let touch = this.scene.input.getTouch(0);
            //是否为新一次触碰，并未发生移动
            if (this.first){
                //获取触碰点的位置
                this.lastPosition.x = touch._position.x;
                this.lastPosition.y = touch._position.y;
                this.first = false;
            }
            else{
                //移动触碰点
                let deltaY = touch._position.y - this.lastPosition.y;
                let deltaX = touch._position.x - this.lastPosition.x;
                this.lastPosition.x = touch._position.x;
                this.lastPosition.y = touch._position.y;
                //根据移动的距离进行旋转
                this.rotate.setValue(1 * deltaY /2, 1 * deltaX / 2, 0);
                this.owner.transform.rotate(this.rotate, true, false);
            }
        }
        else if (2 === touchCount){
            this.text.text = "触控点为2";
            this.isTwoTouch = true;
            //获取两个触碰点
            let touch = this.scene.input.getTouch(0);
            let touch2 = this.scene.input.getTouch(1);
            //是否为新一次触碰，并未发生移动
            if (this.twoFirst){
                //获取触碰点的位置
                this.disVector1.x = touch.position.x - touch2.position.x;
                this.disVector1.y = touch.position.y - touch2.position.y;
                this.distance = Laya.Vector2.scalarLength(this.disVector1);
                this.twoFirst = false;
            }
            else{
                this.disVector2.x = touch.position.x - touch2.position.x;
                this.disVector2.y = touch.position.y - touch2.position.y;
                let distance2 = Laya.Vector2.scalarLength(this.disVector2);
                //根据移动的距离进行缩放
                this.translate.setValue(0, 0, -0.01 * (distance2 - this.distance));
                this.camera.transform.translate(this.translate);
                this.distance = distance2;
            }   
        }
        else if (0 === touchCount){
            this.text.text = "触控点归零";
            this.first = true;
            this.twoFirst = true;
            this.lastPosition.x = 0;
            this.lastPosition.y = 0;
            this.isTwoTouch = false;
        }
    }
   onLateUpdate() {
    }
}