Unity: Raycast Doesn't Work For The Child Object's Collider

Question

I have a tile based game. I place towers as child objects of tiles. I want to be able to detect mouse clicks on towers but not tiles, with raycasting. Both tiles and the towers have 2d box colliders. I can detect clicks on tiles but raycast won't detect the ones on the towers. How can I solve this problem. Thanks.

Here is my code for raycasting:

if (Input.GetMouseButtonDown(0))
        {
            Ray ray = camera.ScreenPointToRay(Input.mousePosition);

            ray.origin = camera.transform.position;

            RaycastHit2D hit = Physics2D.Raycast(camera.transform.position, -Vector2.up, 50, 8);

            if (hit.collider != null && !EventSystem.current.IsPointerOverGameObject())
            {
                Debug.Log(hit.collider.transform.tag);
                //Transform objectHit = hit.transform;

            }
        }
    }

When I mask the tiles (here layer 8) I get nothing. It seems rays never hit the towers although towers (like tiles) also have a 2d box collider.

Can you show a screenshot of the properties of the problematic collider? Is the raycast hitting anything at all? More details will help narrow the problem down to an answerable state. — Serlite
You can check with collider of tiles and find if tiles have child then control it... https://docs.unity3d.com/ScriptReference/Transform.GetChild.html — Cổ Chí Tâm
Please ask the actual question. Try to describe issue as good as its possible — Greg Lukosek
I edited the question. Can you have a look at it now? @Serlite — Rookie

Mr.Bigglesworth Mr.Bigglesworth · Accepted Answer · 2017-03-03T11:34:06

Unity uses a layer system and you can filter out which layers raycasts are using. You can use this to hit specific colliders and avoid others like your tiles/ towers issue. The syntax (for 2d version) is:

RaycastHit2D Raycast(Vector2 origin, Vector2 direction, float distance
= Mathf.Infinity, int layerMask = DefaultRaycastLayers, float minDepth
= -Mathf.Infinity, float maxDepth = Mathf.Infinity);

Here you can see the layermask parameter choose a different layer to the one your parent object is on. Then place the children on a different layer using the drop down menu in the inspector as seen below.

You can set the layers of parents and child gameobjects separately.

Hope that helps

Unity: Raycast Doesn't Work For The Child Object's Collider

2 Answers