Accessing rootNode

In my main class, which extends SimpleApplication I have access to rootNode which gets rendered.
What is best practice for passing this around to States/Systems that need it, just passing it via the constructor?

As a side note, I’m not entirely clear on how rendering works in the Asteroids example, does it use the same rootNode somewhere?

I’ve answered all of my own questions, didn’t realise there was a getRootNode() method. I shouldn’t code while sick.