Unity sprite with higher sorting layer not firing its OnMouseDown function

Question

I have 2 objects, both have a Box collider 2D.

The first object is on the Level1 Sorting Layer and has a Tile script attached to it.

The second object is on the Level0 Sorting Layer and doesn't have any scripts.

The Tile script code is as follows:

void OnMouseDown()
{
    Debug.Log(Input.mousePosition.ToString());
}

Whenever I click the top tile, nothing prints in the console unless I click on the red area like I show in the image below (red area = [first box collider] minus [the two box colliders intersection area]).

Why this happens ? Why doesn't the OnMouseDown() function fire up simply when you click on its collider, since the top tile is on a higher sorting layer than the bottom tile. How does this work ? Doesn't sorting layer affect the 2D box collider ? (If I change the Z-axis of the top tile to -1, while keeping the bottom tile to 0, it works as expected.)

Answer 1

If you have stacked BoxCollider2Ds like that, Unity will only capture the mouse click on the topmost one.

You could:

• Adjust the z-layer of your colliders (I think you do this by setting the renderer's "Order in Layer").

• Enable/Disable your colliders in code based on which one is on top.

• Do a RaycastAll, and process the click yourself.