public void LookatModel()
    {
        targetVector3 = model.position + model.right * 5;//设置相机的位置在模型的右侧5单位远处
        Vector3 dir = model.position - targetVector3;  //获取摄像机的朝向
        transform.DOMove(targetVector3,2f);
        Quaternion q = Quaternion.LookRotation(dir);  //将朝向转换成四元数
        targetEuler = q.eulerAngles;  //四元数转换成欧拉角
        transform.DORotate(targetEuler, 2,RotateMode.Fast) ;
    }