Collision between two boxes

[Dmitry-Sedov]

I added two collided boxes: 1) the first box is [0.0,0.0,0.0] - [1.0, 1.0, 1.0] 2) the second box is [0.0,0.8,0.0] - [1.0, 1.0, 1.0]. As you can see the second box is completely in the first one and all vertices of the second box are on the sides of the first box. Anyway, for this case the function collide returns penetration value = 1.0. But if we change original boxes like this 1) the first box is [0.0,0.0,0.0] - [1.0, 1.0, 2.0] 2) the second box is [0.0,0.8,0.0] - [1.0, 1.0, 2.0] (we scale them along Z) then "collide" returns penetration = 0. The same value will be if we scale them along Y. My question is how can I detect collisions where one body is completely inside another one and is there solid method to take the maximum penetration depth?