onmousedown事件（）只要求最重要的游戏对象

我不认为OnMouseDown是一个很好的方法。您可以使用2D RayCast来获得最顶级的对撞机。用这种方法你将不得不自己对排序​​层和排序顺序进行说明。

诀窍检查2D单个点到不给光线投射方向与如下所示：

Physics2D.Raycast(touchPostion, Vector2.zero); 

这里是我扔在一起的例子，不考虑使用排序的层，只排序顺序。

using UnityEngine; 
public class RayCastMultiple : MonoBehaviour 
{ 
    //Current active camera 
    public Camera MainCamera; 
    // Use this for initialization 
    void Start() 
    { 
     if(MainCamera == null) 
      Debug.LogError("No MainCamera"); 
    } 
    // Update is called once per frame 
    void FixedUpdate() 
    { 
     if(Input.GetMouseButtonDown(0)) 
     { 
      var mouseSelection = CheckForObjectUnderMouse(); 
      if(mouseSelection == null) 
       Debug.Log("nothing selected by mouse"); 
      else 
       Debug.Log(mouseSelection.gameObject); 
     } 
    } 
    private GameObject CheckForObjectUnderMouse() 
    { 
     Vector2 touchPostion = MainCamera.ScreenToWorldPoint(Input.mousePosition); 
     RaycastHit2D[] allCollidersAtTouchPosition = Physics2D.RaycastAll(touchPostion, Vector2.zero); 
     SpriteRenderer closest = null; //Cache closest sprite reneder so we can assess sorting order 
     foreach(RaycastHit2D hit in allCollidersAtTouchPosition) 
     { 
      if(closest == null) // if there is no closest assigned, this must be the closest 
      { 
       closest = hit.collider.gameObject.GetComponent<SpriteRenderer>(); 
       continue; 
      } 
      var hitSprite = hit.collider.gameObject.GetComponent<SpriteRenderer>(); 
      if(hitSprite == null) 
       continue; //If the object has no sprite go on to the next hitobject 
      if(hitSprite.sortingOrder > closest.sortingOrder) 
       closest = hitSprite; 
     } 
     return closest != null ? closest.gameObject : null; 
    } 
} 

这是非常简单，只是我的回答重复的位置：Game Dev Question