void Update()
{
// attach map renderer to planetarium camera once
if (MapView.MapIsEnabled && map_camera_script == null)
{
map_camera_script = PlanetariumCamera.Camera.gameObject.AddComponent <MapCameraScript>();
}
// process keyboard input
Misc.KeyboardInput();
// add description to techs
Misc.techDescriptions();
// set part highlight colors
Highlighter.update();
// prepare gui content
UI.update(callbacks.visible);
}