Question Collider2D.Cast does not seem to respect Collider2D.excludeLayers

Hi,

the way I understand Collider2D's excludeLayers property is that the collider, including its Cast method, should not look for collisions on excluded layers. By that logic, the following code should never run the log line, whatever direction, distance or the excludeLayers mask might be:

Code (CSharp):

1.  
2. Collider2D collider = gameObject.GetComponent<Collider2D>();
3. RaycastHit2D[] castResults = new RaycastHit2D[1];
4. int numCastResults = collider.Cast(direction, castResults, distance);
5. if (numCastResults == 1)
6. {
7.     if ((collider.excludeLayers & (1 << castResults[0].collider.gameObject.layer)) != 0)
8.     {
9.         Debug.Log("collision with an object on an excluded layer :/");
10.     }
11. }
12.  

I do encounter the log message though, when a game object on an excluded layer is in collision range. I'm sure I can work around it, I'd just like to understand where my misconception of excludeLayers and Cast lies.

 

Thank you, that's really unintuitive to me ^^ I'd expect my casts to follow the exact same collision rules that my object's physics adhere to. Just a way to manually check collision instead of waiting for the collision to happen and reacting to events.

How so? The docs are my primary source of information and I've spent quite some time browsing them before I asked here. Neither the docs for Collider2D.Cast nor the docs for excludeLayers say anything about the fact the collision matrix and everything related only applies to physics simulation. Even if the Cast doc page included the default value for contactFilter (which it doesn't), that still doesn't mean that the excludeLayers mask isn't consulted in addition to the filter.

In fact, I can't find a source that has the info you just gave me, even though I know exactly what I'm looking for now. The closest I found is the use of layers doc page, which says:
> If you don’t pass a LayerMask to the ray cast API call, Unity uses Physics.DefaultRaycastLayers which matches every layer except Ignore Raycast.
That's for Physics.Raycast though, so not a Collider2D thing.

I guess we can move this post to be documentation feedback instead of a 2d physics question ^^

 

Thanks for getting back to this, and get well soon! I can imagine, after 10 years and over 10k posts, there are quite a few reoccuring patterns in the question posts

I've submitted a bug report, referencing this thread

 

Thanks, it's IN-61268