Unity 2d collision

Unity Engine
1

Hi,

I have a circle collider within another bigger circle collider. How can I detect when the smaller circle collider moving within the bigger one hits the edge of the bigger circle collider. I can detect when it leaves completely, but I want to detect when it first starts to leave. I would assume this is easy and I googled but can’t find a good way to phrase it to find the results I need.

Thanks

2

I correctly understand that you need it?

3

Now I understood your question correctly. What if around a small collider to make some more smaller colliders and to check by means of them?
Or use Ray?

4

Hmmm… is there no way to detect when one collider starts to exit the other or a way to detect when the extremity of one collider touches the extremity of another? Picture a small circle within a big one, as soon as the small one touches the big one, I want to trigger something.