鼠标拖动2D物体（图片）

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

[RequireComponent(typeof(Image))]
public class DragMe : MonoBehaviour, IBeginDragHandler, IDragHandler,IEndDragHandler
{
    public bool dragOnSurfaces = true;

    public GameObject m_DraggingIcon;
    private RectTransform m_DraggingPlane;

    public void OnBeginDrag(PointerEventData eventData)
    {
        var canvas = FindInParents<Canvas>(gameObject);
        if (canvas == null)
            return;

        // We have clicked something that can be dragged.
        // What we want to do is create an icon for this.
        m_DraggingIcon = new GameObject("icon");

        m_DraggingIcon.transform.SetParent(canvas.transform, false);
        m_DraggingIcon.transform.SetAsLastSibling();

        var image = m_DraggingIcon.AddComponent<Image>();
        // The icon will be under the cursor.
        // We want it to be ignored by the event system.
        CanvasGroup group = m_DraggingIcon.AddComponent<CanvasGroup>();
        group.blocksRaycasts = false;

        image.sprite = GetComponent<Image>().sprite;
        image.SetNativeSize();

        if (dragOnSurfaces)
        {
            m_DraggingPlane = transform as RectTransform;
        }
        else
        {
            m_DraggingPlane = canvas.transform as RectTransform;
        }
        SetDraggedPosition(eventData);
    }

    public void OnDrag(PointerEventData data)
    {
        if (m_DraggingIcon != null)
        {
            SetDraggedPosition(data);
        }
        transform.position = m_DraggingIcon.transform.position;
        m_DraggingIcon.SetActive(false);
    }

    private void SetDraggedPosition(PointerEventData data)
    {
        if (dragOnSurfaces && data.pointerEnter != null && data.pointerEnter.transform as RectTransform != null)
        {
            m_DraggingPlane = data.pointerEnter.transform as RectTransform;
        }
        var rt = m_DraggingIcon.GetComponent<RectTransform>();
        Vector3 globalMousePos;
        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(m_DraggingPlane, data.position, data.pressEventCamera, out globalMousePos))
        {
            rt.position = globalMousePos;
            rt.rotation = m_DraggingPlane.rotation;
        }
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        if (m_DraggingIcon != null)
            Destroy(m_DraggingIcon);
        Debug.Log("万用表的位置"+transform.position);
    }
    static public T FindInParents<T>(GameObject go) where T : Component
    {
        if (go == null)
        {
            return null;
        }

        var comp = go.GetComponent<T>();

        if (comp != null)
        {
            return comp;
        }

        Transform t = go.transform.parent;
        while (t != null && comp == null)
        {
            comp = t.gameObject.GetComponent<T>();
            t = t.parent;
        }
        return comp;
    }

    
}