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Subjects. The Low-Level Entities
Subjects are the foundational lightweight entities managed by Apparatus. They are mostly UE-independent and consist of Traits and Flags.
Subject Handles
Subjects are not used directly and their internals are hidden deep from the framework user’s perspective. Instead a special concept called Subject Handle is introduced. It’s really much like a weak pointer in terms of Unreal. When you despawn a Subject all of the handles that are currently referencing it become automatically invalid. Internally this is managed through a generation-based referencing technique.
Spawning
Spawning is a process of creating a Subject as part of some Mechanism.
C++ Workflow
In order to spawn a new Subject within the Mechanism, you should call one of the SpawnSubject methods. The simplest one would be:
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FSubjectHandle Subject = Machine::SpawnSubject(); |
If you want to spawn a Subject with some Traits initially attached to it, use the special templated version of the method:
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FBurning Burning{10, 15.5f};FSword Sword{2};FSubjectHandle BurningSword = Machine::SpawnSubject(Burning, Sword); |
Despawning
The despawning process is exactly the opposite of spawning and basically means destroying of a Subject. Destroying an already despawned (or invalid) Subject Handle is a legal operation that does nothing and reports no errors.
C++ Workflow
In order to destroy a Subject in your C++ code, use the Despawn method provided by the Handle structure. Do it like so:
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void PickPowerup(FSubjectHandle Player, FSubjectHandle Powerup){ // Add health/energy/strength to the player... ... // Remove the item from the world: Powerup.Despawn();} |