center's position and it's radius

[farzadshbfn]

This way, we can reposition center and customize it's radius or by passing nil, it will act as default.

[farzadshbfn]

Oops, just saw other PRs... I think it makes sense to use it in Enum because holding variables in class that are valid Only if other variables are set, is bad coding from my point of view and can lead to bugs.

I think even Direction shod go into Mode.linear(Direction)