unity 实现UI-背包装备拖拽功能

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
public class Drag : MonoBehaviour, IBeginDragHandler, IEndDragHandler, IDragHandler, ICanvasRaycastFilter
{
    private Transform nowparent;//记录原始坐标位置
    private bool isRaycastLocationValid = true;//默认射线不能穿透物体
    public Transform IconList;
    /// <summary>
    /// 开始拖拽
    /// </summary>
    public void OnBeginDrag(PointerEventData eventData)
    {
        this.transform.SetAsLastSibling();
        nowparent =this.transform.parent;//初始位置
        isRaycastLocationValid = false;//设置为可以穿透
        transform.SetParent(IconList);//将当前拖拽的物品放在最外层下 效果：可以挡住随意UI 避免呗其他UI挡住
    }
    /// <summary>
    /// UI跟随 鼠标
    /// </summary>
    /// <param name="eventData"></param>
    public void OnDrag(PointerEventData eventData)
    {
        transform.position = Input.mousePosition;
    }
    /// <summary>
    /// 拖拽结束
    /// </summary>
    public void OnEndDrag(PointerEventData eventData)
    {
         //获取鼠标终点位置可能存在的物品
         GameObject go = eventData.pointerCurrentRaycast.gameObject;
        if (go != null)//落点位置不为空
        {
            Debug.Log(go.name);//打印一下落点位置名称
            if (go.tag == ("Gird"))//鼠标终点位置是空格子
            {
                Debug.Log("空格子");
                SetParentAndPosition(transform, go.transform);
            }
            else if (go.tag == transform.tag)//标签相同 放回
            {
                //将拖拽的物品1放到鼠标终点下的位置
                SetParentAndPosition(transform, go.transform);
            }
            else//无效位置，物品回到原来的位置
            {
                SetParentAndPosition(transform, nowparent);
            }
        }
        else
        {
            SetParentAndPosition(transform, nowparent);
        }
        isRaycastLocationValid = true;//射线不可以穿透物体
    }
    // 将child放到parent下做其子物体
    private void SetParentAndPosition(Transform child, Transform parent)
    {
        child.SetParent(parent);
        child.position = parent.position;//子物体的坐标跟随父物体
    }
    public bool IsRaycastLocationValid(Vector2 sp, Camera eventCamera)
    {
        return isRaycastLocationValid;
    }
}