using System.Collections;
using System.Collections.Generic;
using UnityEditor;
using UnityEngine;
using UnityEngine.EventSystems;

public class AniRayTest : MonoBehaviour
{
List list = new List();

// Update is called once per frame
void Update()
{
    /// 鼠标左键没有点击，就不执行判断逻辑
    if (!Input.GetMouseButtonDown(0))
    {
        return;
    }

    ///相应的GameObject对象
    GameObject go = null;

    ///判断是否点再ui上
    if (EventSystem.current.IsPointerOverGameObject())
    {
        go = ClickUI();
    }
    else
    {
        go = ClickScene();
    }

    if (go == null)
    {
        Debug.Log("Click Nothing");
    }
    else
    {
        // 高亮点中GameObject
        EditorGUIUtility.PingObject(go);
        Selection.activeObject = go;
        Debug.Log(go, go);
    }

}

/// <summary>
/// 点中ui
/// </summary>
private GameObject ClickUI()
{
    //场景中的EventSystem

    PointerEventData eventData = new PointerEventData(EventSystem.current);

    //鼠标位置
    eventData.position = Input.mousePosition;

    //调用所有GraphicsRacaster里面的Raycast，然后内部会进行排序，
    //直接拿出来，取第一个就可以用了
    EventSystem.current.RaycastAll(eventData, list);

    //这个函数抄的unity源码的，就是取第一个值
    var raycast = FindFirstRaycast(list);

    //获取父类中事件注册接口
    //如Button，Toggle之类的，毕竟我们想知道哪个Button被点击了，而不是哪张Image被点击了
    //当然可以细分为IPointerClickHandler, IBeginDragHandler之类细节一点的，各位可以自己取尝试
    var go = ExecuteEvents.GetEventHandler<IEventSystemHandler>(raycast.gameObject);

    //既然没拿到button之类的，说明只有Image挡住了，取点中结果即可
    if (go == null)
    {
        go = raycast.gameObject;
    }
    return go;


}

/// <summary>
/// Return the first valid RaycastResult.
/// </summary>
private RaycastResult FindFirstRaycast(List<RaycastResult> candidates)
{
    for (var i = 0; i < candidates.Count; ++i)
    {
        if (candidates[i].gameObject == null)
            continue;

        return candidates[i];
    }
    return new RaycastResult();
}

/// <summary>
/// 点中场景中对象
/// 然后无聊嘛，顺便把点场景的也顺手做了，不过这部分网上介绍挺多的，就不展开说了。
/// </summary>
private GameObject ClickScene()
{
    Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
    RaycastHit hit;
    if (Physics.Raycast(ray, out hit))
    {
        GameObject go = hit.collider.gameObject;
        return go;
    }

    return null;
}

}