Detecting collisions without rigidbody

Hello, I'm trying to create script that will connect walls object by changing the sprite of the wall object.
For every wall I created 4 children with box colliders (Up, Down, Left, Right) to check if wall is near another object with wall tag.

But there's my problem, I know how to check collisions and collider tag using OnCollisionEnter but I heard that it won't work when there's no rigidbody in any of the objects. And creating 4x rigidbody for object which will be multiplied hundred times on one scene is IMO bad option.

Any solution?

 

To detect collisions, a minimum of one of the two objects in the collision need a rigidbody.

 

Yeah, I know, but isn't adding rigidbody to hundreds objects in one scene a bad idea? Isn't there any better way of doing it?

 

Adding a rigidbody to hundreds of objects is fine, it all depends on how you code the collisions and physics.

Any Rigidbody/Physics stuff should be calculated in FixedUpdate() and not in Update()

 

It IS possible to check collision without rigid body. Check this out http://www.theappguruz.com/blog/collision-detection-without-rigid-body-in-unity

 

to me this screams "raycast!!" rather than collisions... is this taking place in real time when the game is running (i.e. things change as the player plays) or is it within the "level generation" step right at the beginning?

edit: hmm old thread,

 

Putting this here in case somebody else wants to try this -

There is an option to add 'isTrigger' property in any collider and you can listen to TriggerEvent in your script. This will work without having a rigidbody at all. But you do need to have colliders on the objects that have to collide.

 

Old threat, but shows up on google, and before others try like me for quite some time:
As far as I know, you Do need a rigidbody. I tried again to make it work without now, but the Documentation (from 2019.4 and many others before) clearly states it does not work without rigidbodies. Are you sure you had no rididbody attached? In that case I would be very interested in more details how you made it work...

 

What about former version?