Unity 如何获取鼠标停留位置下的物体

/// <summary>
    /// 获取鼠标停留处UI
    /// </summary>
    /// <param name="canvas"></param>
    /// <returns></returns>
    public GameObject GetOverUI(GameObject canvas)
    {
        PointerEventData pointerEventData = new PointerEventData(EventSystem.current);
        pointerEventData.position = Input.mousePosition;
        GraphicRaycaster gr = canvas.GetComponent<GraphicRaycaster>();
        List<RaycastResult> results = new List<RaycastResult>();
        gr.Raycast(pointerEventData, results);
        if (results.Count != 0)
        {
            return results[0].gameObject;
        } 
        return null;
    }

/// <summary>
    /// 获取鼠标停留处物体
    /// </summary>
    /// <param name="raycaster"></param>
    /// <returns></returns>
    public GameObject GetOverGameObject(GameObject raycaster)
    {
        PointerEventData pointerEventData = new PointerEventData(EventSystem.current);
        pointerEventData.position = Input.mousePosition;
        PhysicsRaycaster pr = raycaster.GetComponent<PhysicsRaycaster>();
        List<RaycastResult> results = new List<RaycastResult>();
        pr.Raycast(pointerEventData, results);
        if (results.Count != 0)
        {
            return results[0].gameObject;
        } 
        return null;
    }

/************************************************************
* 版本声明：v1.0.0
* 类 名 称：MouseOverController.cs
* 创建日期：2019/8/10 16:10:44
* 作者名称：末零
* 功能描述：获取鼠标停留处的物体
************************************************************/ 
using System.Collections.Generic; 
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI; 
namespace LastZero.Utility
{
    public class MouseOverController
    {
        /// <summary>
        /// 获取鼠标停留处UI
        /// </summary>
        /// <param name="canvas"></param>
        /// <returns></returns>
        public static GameObject GetOverUI(GameObject canvas)
        {
            PointerEventData pointerEventData = new PointerEventData(EventSystem.current);
            pointerEventData.position = Input.mousePosition;
            GraphicRaycaster gr = canvas.GetComponent<GraphicRaycaster>();
            List<RaycastResult> results = new List<RaycastResult>();
            gr.Raycast(pointerEventData, results);
            if (results.Count != 0)
            {
                return results[0].gameObject;
            } 
            return null;
        } 
        /// <summary>
        /// 获取鼠标停留处UI
        /// </summary>
        /// <param name="canvas"></param>
        /// <returns></returns>
        public static GameObject GetOverGameObject(GameObject camera)
        {
            if (camera.GetComponent<PhysicsRaycaster>() == null)
                camera.AddComponent<PhysicsRaycaster>(); 
            PointerEventData pointerEventData = new PointerEventData(EventSystem.current);
            pointerEventData.position = Input.mousePosition;
            PhysicsRaycaster gr = camera.GetComponent<PhysicsRaycaster>();
            List<RaycastResult> results = new List<RaycastResult>();
            gr.Raycast(pointerEventData, results);
            if (results.Count != 0)
            {
                return results[0].gameObject;
            } 
            return null;
        }
    }
}

using UnityEngine;
using System.Collections;
public class Cube : MonoBehaviour {
//    public Transform cube;
    bool isShowTip;
//    // Use this for initialization
    void Start () {
        isShowTip=false;
    }    
    void OnMouseEnter () {
        isShowTip=true;
        //Debug.Log (cube.name);//可以得到物体的名字
    }
    void OnMouseExit () {
        isShowTip=false;
    }
    void OnGUI () {
        if (isShowTip){
            GUI.Label(new Rect(Input.mousePosition.x,Screen.height-Input.mousePosition.y,100,40),"afdasdfasdf"); 
         }  
    }
}