Unity常用的三种拖拽方法（内置方法 + 接口 + Event Trigger组件）

三种常用拖拽方法OnMouseDrag等内置方法、Event Trigger组件、拖拽接口IDragHandler方法

Unity内置方法实现:

  #region Drag2DSprite  加上2D碰撞体
    //[SerializeField] private bool isSelected;

    //void Start()
    //{

    //}
    //void Update()
    //{
    //    //Debug.Log(Input.mousePosition.x+" , "+Input.mousePosition.y);
    //    if (isSelected)
    //    {
    //        //屏幕坐标系转化世界坐标系 SCREEN POS -> WORLD SPACE
    //        Vector2 CursorPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
    //        transform.position = new Vector2(CursorPos.x,CursorPos.y);
    //    }
    //}

    //private void OnMouseOver()
    //{
    //    if (Input.GetMouseButtonDown(0))
    //        isSelected = true;
    //    if (Input.GetMouseButtonUp(0))
    //        isSelected = false;
    //}
    #endregion
    /// <summary>
    /// OnMouseDrag方法不合适对UI对象来进行拖拽
    /// </summary>
    private void OnMouseDrag()
    {
        //SCREEN POS -> WORLD SPACE
        Vector3 cursorPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
        transform.position = new Vector3(cursorPos.x, cursorPos.y);
    }
    private void OnMouseEnter()
    {
        transform.localScale += Vector3.one * 0.2f;
    }
    private void OnMouseExit()
    {
        transform.localScale -= Vector3.one * 0.2f;
    }

Event Trigger组件实现:

    private Vector3 startPos;

    private void Start()
    {
        //Debug.Log(transform.GetComponent<RectTransform>().localPosition);
        startPos = transform.position; 
    }

    public void DragMethod()
    {
        transform.position = Input.mousePosition;
    }

    public void DropMethod()
    {
        GameObject fillGo = GameObject.Find("Fill");

        float dist = Vector3.Distance(transform.position, fillGo.transform.position);

        if (dist <= 100)
        {
            transform.position = fillGo.transform.position;
        }
        else
        {
            transform.position = startPos;
        }
    }

接口实现：

（1）

    [SerializeField] private RectTransform panelRectTrans;

    //OPTIONAL
    //private RectTransform panelRectTrans;

    //private void Awake()
    //{
    //    if (panelRectTrans == null)
    //        panelRectTrans = transform.parent.GetComponent<RectTransform>();
    //}

    public void OnDrag(PointerEventData eventData)
    {
        panelRectTrans.anchoredPosition += eventData.delta;
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        panelRectTrans.SetAsLastSibling();
    }

    //public void OnPointerDown(PointerEventData eventData)
    //{
    //    panelRectTrans.SetAsLastSibling();
    //}

（2）

    public void OnBeginDrag(PointerEventData eventData)
    {
        Vector3 globalMousePos;
        //将屏幕坐标转换成世界坐标
        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(rectTransform, eventData.position, eventData.enterEventCamera, out globalMousePos))
        {
            //计算UI和指针之间的位置偏移量
            dirV3 = rectTransform.position - globalMousePos;
        }
    }
    public void OnDrag(PointerEventData eventData)
    {
        Vector3 pos;
        RectTransformUtility.ScreenPointToWorldPointInRectangle(rectTransform, eventData.position, eventData.enterEventCamera, out pos);
        rectTransform.position = pos + dirV3;
    }

知乎/简书大佬有关坐标系的文章：

1.https://zhuanlan.zhihu.com/p/93813556
2.https://www.jianshu.com/p/695353725e7a
3.https://www.jianshu.com/p/baf6bedddb91

注，效果自行动手尝试哦！