@
DanieLoche
: Thanks for your proposition, but my main problem is not how to implement it (I can do that easilly), but more how to make it easy to use. I don't think "blindly" moving the center of rotation is the best. Moreover, with the mouse you can cover 2 axis while you need to be able to move on 3 axis to be able to cover all possible position. Or you can just move the camera up/down/left/right depending on the current view, but then it will be hard for the user to move it back to its first place, for instance.
In the case of HexScape, I think choosing a tile to be the center of rotation is a better idea. So I'll probably just add a button to allow choosing another tile to be the center of the rotation.