GameScreen

The main screen of the game where all of the actual flight- and waypoint-related logic starts.

Initialisation

Accepts the GameDifficulty variable, which is passed on to AircraftController (AicraftController).

Also initiates all of the UI elements:

// create a table layout, main ui
Table ui = new Table();

// create a separate layout for sidebar with all the buttons and
// required info
Table sidebar = new Table();

// create and add the Airspace group, contains aircraft and waypoints
Airspace airspace = new Airspace();

ui basically holds both the sidebar and airspace, first of which is another table which is used as a wrapper for all of the elements in the sidebar (simplifies management of the layout).

Render

Basically calls the Stage's draw method which in turn calls all of the draw method of all of the actors in the stage. For more info about the Stage/Actor logic see Stage/Actor