Unity/3d/2dから3dの座標変換

void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            Vector3 screenPoint = Input.mousePosition;
            GameObject canvas = GameObject.Find("Canvas");
            Camera camera = GameObject.Find("Main Camera").GetComponent<Camera>();
            RectTransform canvasRect = canvas.GetComponent<RectTransform>();
            Vector3 worldPoint = Vector3.zero;
            RectTransformUtility.ScreenPointToWorldPointInRectangle(canvasRect, screenPoint, camera, out worldPoint);
            Debug.Log("worldPoint.x=" + worldPoint.x + " y=" + worldPoint.y);
            GameObject.Find("Whale2").transform.position = new Vector3(
                worldPoint.x,
                worldPoint.y,
                0);
        }
    }

参考：https://light11.hatenadiary.com/entry/2019/04/16/003642