1.BasePanel和UIManager
子类面板继承BasePanel，UIManager实现动态创建面板，展示面板，隐藏面板，得到面板
（1）单例类
（2）canvas设置为预制体，将新创建的面板设置为该子类
（3）面板和预制体名字一致

 abstract class BasePanel : MonoBehaviour
{
    private CanvasGroup canvasGroup;

    private float alphaSpeed = 10;

    public bool IsShow = false;

    private UnityAction hideCallback = null;
    protected virtual void Awake()
    {
        canvasGroup = this.GetComponent<CanvasGroup>();
        if (canvasGroup == null)
            canvasGroup = this.gameObject.AddComponent<CanvasGroup>();
    }
    protected virtual void Start()
    {
        Init();
    }
    /// <summary>
    /// 注册控件的方法 让所有的子面板都去注册一些方法 子类必须实现父类中的抽象方法
    /// </summary>
    public abstract void Init();

    public virtual void ShowMe()
    {
        canvasGroup.alpha = 0;
        IsShow = true;
    }
    public virtual void HideMe(UnityAction action)
    {
        canvasGroup.alpha = 1;
        IsShow = false;
        hideCallback = action;
    }
    // Update is called once per frame
    protected virtual void Update()
    {
        //透明度不为1 就一直加 这样可以保证不会反复进入这个方法
        //渐入
        if(IsShow && canvasGroup.alpha != 1)
        {
            canvasGroup.alpha += alphaSpeed * Time.deltaTime;
            if(canvasGroup.alpha >= 1)
                canvasGroup.alpha = 1;
        }
        //渐出
        else if (!IsShow && canvasGroup.alpha != 0)
        {
            canvasGroup.alpha -= alphaSpeed * Time.deltaTime;
            if (canvasGroup.alpha <= 0)
            {
                canvasGroup.alpha = 0;
                hideCallback?.Invoke();
            }
        }
    }
}

public class UIManager
{
	//不继承mono 所以可以new
    private static UIManager instance = new UIManager();
    public static UIManager Instance => instance;
    
    private Transform canvasTrans;
	
	//在构造函数中对canvas进行初始化
    public UIManager()
    {
        GameObject canvasObj = GameObject.Instantiate(Resources.Load<GameObject>("UI/Canvas"));
        canvasTrans = canvasObj.transform;
        GameObject.DontDestroyOnLoad(canvasObj);
    }
    //字典管理已经显示过的面板 当需要隐藏时就移除该面板
    private Dictionary<string, BasePanel> panelDic = new Dictionary<string, BasePanel>();
    //显示面板
    //泛型约束：是BasePanel类或者BasePanel子类都可以
    public T ShowPanel<T>() where T : BasePanel
    {
        //要保证泛型T的类型 和 面板预制体名字一致
        string panelName = typeof(T).Name;
        //判断字典中是否显示过该面板
        //显示过就返回该面板
        if (panelDic.ContainsKey(panelName))
        {
            return (T)panelDic[panelName];
        }
        //字典没有 那就根据面板名字 实例化对象
        GameObject panelObj = GameObject.Instantiate(Resources.Load<GameObject>("UI/" + panelName));
        //设置父对象为canvas的transform
        panelObj.transform.SetParent(canvasTrans, false);
        //得到面板中的对应脚本
        T panel = panelObj.GetComponent<T>();
        //存储面板中的脚本在字典中，方便获取和隐藏
        panelDic.Add(panelName, panel);
        //显示逻辑
        panel.ShowMe();
        return panel;
    }
    /// <summary>
    /// 隐藏面板
    /// </summary>
    /// <typeparam name="T">面板类名</typeparam>
    /// <param name="isFade">是否淡出完毕过后才删除面板，true为是</param>
    public void HidePanel<T>(bool isFade = true) where T : BasePanel
    {
        string panelName = typeof(T).Name;
        if (panelDic.ContainsKey(panelName))
        {
            if (isFade)
            {
                //面板淡出过后删除
                panelDic[panelName].HideMe(() =>
                {
                    //删除对象 并删除字典中存储的脚本
                    GameObject.Destroy(panelDic[panelName].gameObject);
                    panelDic.Remove(panelName);
                });
            }
            else
            {
                //删除对象 并删除字典中存储的脚本
                GameObject.Destroy(panelDic[panelName].gameObject);
                panelDic.Remove(panelName);
            }
        }
    }
    //得到面板
    public T GetPanel<T>() where T : BasePanel
    {
        string panelName = typeof(T).Name;

        if (panelDic.ContainsKey(panelName))
        {
            return (T)panelDic[panelName];
        }
        return null;
    }
}

2.摄像机跟随人物
（1）首先要设置看向的人物，摄像机的偏移（偏移多少），看向人物的偏移（头还是脚），移动速度和旋转速度

public class CameraMove : MonoBehaviour
{
    //摄像机看向的目标
    public Transform target;
    //摄像机相对目标位置的偏移值
    public Vector3 offsetPos;
    //看向位置的y的偏移值（看向人的脚还是头)
    public float bodyHeight;
    //移动和旋转速度
    public float moveSpeed;
    public float rotationSpeed;
	//目标位置
    private Vector3 targetPos;
    //目标旋转四元数
    private Quaternion targetRot;
    private void Update()
    {
        if (target == null) return;
        //根据目标对象 计算 摄像机当前的位置和角度
        //位置的计算
        //向后偏移z坐标
        targetPos = target.position + target.forward * offsetPos.z;
        //向上偏移y坐标
        targetPos += target.up * offsetPos.y;
        //左右偏移x坐标
        targetPos += target.right * offsetPos.x;
        //通过插值运算 让摄像机不断的向目标点靠拢
        this.transform.position = Vector3.Lerp(this.transform.position, targetPos, moveSpeed + Time.deltaTime);
        //旋转
        //人物位置 + 向上偏移 = 人物身体的点 - 摄像机的点 = 向量
        //得到最终要看向哪个点的四元数
        targetRot = Quaternion.LookRotation(target.position + Vector3.up * bodyHeight - this.transform.position);
        //让摄像机不断的向这个角度靠拢
        this.transform.rotation = Quaternion.Slerp(this.transform.rotation, targetRot, rotationSpeed * Time.deltaTime);
    }
    public void SetTarget(Transform player)
    {
        this.target = player;
    }
}