Unity UI实现拖拽旋转

[SerializeField] private Canvas m_Canvas;
    
    private Vector3? CalculateWorldToScreenPos(Vector3 worldPos)
    {
        if (m_Canvas.renderMode == RenderMode.ScreenSpaceCamera)
        {
            return m_Canvas.worldCamera.WorldToScreenPoint(worldPos);
        }
        else if (m_Canvas.renderMode == RenderMode.ScreenSpaceOverlay)
        {
            Vector3 screenPos = m_Canvas.transform.InverseTransformPoint(worldPos);
            var rectTrans = m_Canvas.transform as RectTransform;
            screenPos.x += rectTrans.rect.width * 0.5f * rectTrans.localScale.x;
            screenPos.y += rectTrans.rect.height * 0.5f * rectTrans.localScale.y;
            return screenPos;
        }

        return null;
    }
    
    public void OnDrag(PointerEventData eventData)
    {
        if (eventData.button != PointerEventData.InputButton.Left) return;
        
        //计算当前物体距离画布左下角位置
        Vector3? curScreenPos = CalculateWorldToScreenPos(transform.position);
        if (curScreenPos == null) return;
        //鼠标位置偏移量
        Vector2 offset = eventData.position - (Vector2)curScreenPos.Value;
        if (offset != Vector2.zero)
        {
            transform.rotation = Quaternion.FromToRotation(Vector3.up, offset);
        }
    }

//旋转速度
[SerializeField] private float m_RotateSpeed;
    
    public void OnDrag(PointerEventData eventData)
    {
        if (eventData.button != PointerEventData.InputButton.Left) return;

        //手指滑动偏移量
        Vector2 mouseXY = eventData.delta;
        mouseXY *= m_RotateSpeed;

        //计算当前物体距离画布左下角位置
        Vector3? curScreenPos = CalculateWorldToScreenPos(transform.position);
        if (curScreenPos == null) return;
        //手指位置偏移量
        Vector2 offset = eventData.position - (Vector2)curScreenPos.Value;

        float value;
        if (Mathf.Abs(mouseXY.x) > Mathf.Abs(mouseXY.y)) // 判断水平滑动还是垂直滑动
        {
            //手指往水平滑动   下面旋转跟随偏移参数  上面与偏移参数相反
            value = mouseXY.x * Mathf.Sign(-offset.y);
        }
        else
        {
            //手指垂直滑动    右边跟随偏移参数    左边与偏移参数相反
            value = mouseXY.y * Mathf.Sign(offset.x);
        }

        transform.Rotate(Vector3.forward, value, Space.Self);

    }