Hello everyone, I’m trying to get this result : a sphere colliding within another bigger sphere ( like a lottery ball machine).
I guess opening the bigger sphere would do the trick but I wonder why the small sphere goes directly out of the big one ?
see this playground :
Hi @David_Peeters,
This is because physics engines work with rigid full bodies and not only shells. which means - you can’t really put a sphere in a sphere. you can put a sphere in a mesh that is an empty shell.
Putting a sphere in a sphere is just like placing your character in a wall - the physics engine will calculate that as collision and will “throw” the object out, until the collision was resolved. Which usually results in the funniest physics interaction 
Thank you for your answer it helped a lot to figure how to slove this, here is how I did it:
https://playground.babylonjs.com/#DGEP8N#17
basically create another sphere within the first one, then merge both as one mesh and use BABYLON.PhysicsImpostor.MeshImpostor instead of BABYLON.PhysicsImpostor.SphereImpostor