Explosive Collisions of closely placed objects on Start


I have a collection of closely placed cubic GameObjects with a Rigid body and a Box Collider. I’m certain that they are not touching (I purposely placed a small gap between them to avoid face overlap) yet when I press Start they “explode” outwards, repelled by a collision I assume. What’s weirder is that this sometimes doesn’t happen and the cubes are properly placed. It doesn’t seem consistent. I’m not sure why that happens and any feedback would be much appreciated. (I tried to upload an image to show the problem but for some reason it’s not parsing the image…)

What’s the area of influence of a collider if it reaches outside of the boundaries set by the box collider? (I have the exact same scale on my cube as I have on my box collider) Is there any obvious solution other than widening the gap?

Thanks for considering my question.


Took me forever to understand why Unity was detecting collisions between objects that were clearly not touching. Turns out that Colliders have a contact offset distance below which Unity detects and keeps track of a collision even if the objects are not technically touching. Changing the max Depenetration Velocity of my rigid bodies also helps reduce the ‘explosive’ correction of overlapping rigidbodies.

But my main problem was related to the fact that I thought the box collider would have to be the same size as the object in tranform (local scale), when actually size 1 of the box collider is already scaled to the size of the game object. So actually, I was using a bigger box collider than the size of my object… facepalm