Found a solution, I concluded that the class where the CSceneGraph is a member of, doesn't have the pointer/reference to the d3dscene (as member initially), so a const reference is out of the question.

I therefor now made a const pointer member to the d3dscene in my scenegraph class, which I set in the create call.

So there's only 1 member function left needing the const pointer as function parameter, afterwards all members use the const pointer.

That way the scenegraph member functions can access const members and public variables in the d3dscene class.