Custom Events & Functions

The I/O system was designed in a way to be easily extensible. You can register custom events and functions with the I/O system for any of your actors using the ActorIOInterface.

Adding the I/O Interface to the Actor

In order to expose custom events and functions, you need to add the ActorIOInterface to your actor. The LogicActorBase class already has this interface implemented, so if you are creating a custom logic actor then you can skip this step.

Registering Custom Events

Override the RegisterIOEvents function of the I/O interface, and use RegisterEvent to add an entry to the event registry of this actor. The following types are supported:

• Blueprint event dispatchers

• C++ dynamic multicast delegates

• C++ sparse delegates

void APickupActor::RegisterIOEvents(FActorIOEventList& EventRegistry)
{
	EventRegistry.RegisterEvent(FActorIOEvent()
		.SetId(TEXT("APickupActor::OnPickup"))
		.SetDisplayName(INVTEXT("OnPickup"))
		.SetTooltipText(INVTEXT("Event when the item is picked up."))
		.SetMulticastDelegate(this, &OnPickup));
}

When registering an I/O event, you can also assign an Event Processor for the event. These are used when your event has parameters, and you want to expose them as Named Arguments for actions to use.

Registering Custom Functions

Override the RegisterIOFunctions of the I/O interface, and use RegisterFunction to add an entry to the function registry of the actor. The following types are supported:

• Blueprint functions

• Blueprint custom events

• C++ functions marked as UFUNCTION (no specifiers required)

void APickupActor::RegisterIOFunctions(FActorIOFunctionList& FunctionRegistry)
{
	FunctionRegistry.RegisterFunction(FActorIOFunction()
		.SetId(TEXT("APickupActor::Pickup"))
		.SetDisplayName(INVTEXT("Pickup"))
		.SetTooltipText(INVTEXT("Pickup the item from the ground."))
		.SetFunction(TEXT("Pickup")));
}

When registering an I/O function for an actor, you can specify a SubobjectName. If set, the I/O system will call the function on the specified subobject instead of the actor itself. Using this, you can expose functions from components of your actor.

The SubobjectName should be the name of a component (or any other subobject) that is part of the actor by default. Note that this only works for default subobjects! Dynamically added components will not work.