A GameState object has a reference to a RenderWindow object;
GameState holds an object called Level, which ALSO holds a reference to a RenderWindow object. When constructing Level, can I pass the RenderWindow object reference from my GameState class?
Well that was a little confusing to explain, I hope you understand!
As I understand it, there's any problem passing a reference to another reference. Of course, the very first reference has got to refer to something. As is:
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int x = 0;
int& y = x; // y is a reference to x
int& z = y; // z is another reference to x, init via y
So the answer to:
can I pass the RenderWindow object reference from my GameState class?
Is yes, you can. The two references end up referring to the same actual original variable.