Unity 獲取鼠標懸停位置下的UI或3D物體對象

根據UGUI的射線檢測機制獲取當前鼠標下的UI：

/// <summary>
/// 獲取鼠標停留處UI
/// </summary>
/// <param name="canvas"></param>
/// <returns></returns>
public GameObject GetOverUI(GameObject canvas)
{
PointerEventData pointerEventData = new PointerEventData(EventSystem.current);
pointerEventData.position = Input.mousePosition;
GraphicRaycaster gr = canvas.GetComponent<GraphicRaycaster>();
List<RaycastResult> results = new List<RaycastResult>();
gr.Raycast(pointerEventData, results);
if (results.Count != 0)
{
return results[0].gameObject;
}

return null;
}

其中，results為鼠標下UI的列表。

不僅適用於UGUI，可以在攝像機上添加PhysicsRaycaster組件，傳參為攝像機，這樣就可以獲取3D物體。

/// <summary>
/// 獲取鼠標停留處物體
/// </summary>
/// <param name="raycaster"></param>
/// <returns></returns>
public GameObject GetOverGameObject(GameObject raycaster)
{
PointerEventData pointerEventData = new PointerEventData(EventSystem.current);
pointerEventData.position = Input.mousePosition;
PhysicsRaycaster pr = raycaster.GetComponent<PhysicsRaycaster>();
List<RaycastResult> results = new List<RaycastResult>();
pr.Raycast(pointerEventData, results);
if (results.Count != 0)
{
return results[0].gameObject;
}

return null;
}