Subsystems are actors existing in the world only once and are used as a per world instance general manager. These subsystems are accessible from anywere were you have a world context available (f.e. actors). Subsystems allow you f.e. to implement custom game state information you want to have saved to the save or when you want to manage multiple actors or a system from one centeral point.

f.e. Light It Up uses a group system wich is globaly unified were every lamp can access the same group. LIU now uses a system to provided one point were every lamp can get the information about the current group settings.


If you want to have a subsystem you need at least one class inherited from this holder class. These holders will spawn and store the references to the subsystems.

It has a InitSubsystems where you then need to spawn the subsystems you want to add and then store the references in attributes.

Later somewere else you can use the static K2_GetModSubsystemHolder function to get a reference to your holder which then has attributes holding references to your subsystems.

For registering a subsystem holder you can just add it to the M Mod Subsystem array of the InitMod class.

Spawning a Subsystem

A subsystem it self is a actor inheriting from AFGSubsystem. You can also use save game to store data to save states.

When you spawn one in a subsystem holder you should use the UModSubsystemHolder::SpawnSubsystem function. Cause it also checks if the subsystem is already spawned (f.e. loaded from save state) and returns just the reference to it. The first paramter of the function is a reference to your variable which will then reference the newly spawned or found subsystem. The second paramter tells the function for which class to actuall look for or which class needs to be created. The third paramter is just a name for the actor.

For spawning it in BP you should use the UModSubsystemHolder::K2_SpawnSubsystem function.