Units, Components, and Abilities

SeinARTS keeps designer-facing authoring in Blueprint while the runtime simulation operates on deterministic data.

The Blueprint is the unit

A unit type is a Blueprint subclass of ASeinActor. The actor automatically owns a USeinEntityBridgeComponent, which connects its Unreal presentation to its simulation entity.

Designers add native or Blueprint-authored SeinARTS data components through the unit Blueprint’s Components panel. These derive from USeinEntityComponent. The bridge bakes their authored values into its ComponentData array as deterministic payloads stored in FInstancedStruct entries.

At spawn, the world subsystem copies the authored payloads into reflection-backed simulation storage. After that boundary, simulation systems work with entity handles and component data rather than actors.

Components are data

Components describe state. They do not own event graphs or state-mutating behavior.

Framework simulation structs use the SeinDeterministic metadata marker so the editor can accept them as component payloads and validate their fields. Designers can also create custom deterministic component structs through the editor workflow.

Logic belongs in:

• Abilities.
• Effects.
• AI controllers.
• Command brokers.
• Simulation systems.

Everything is an ability

Gameplay commands share one extensible model. Moving, attacking, harvesting, building, patrolling, garrisoning, and reinforcing are ability Blueprints rather than values in a hard-coded command enum.

C++ provides deterministic primitives, command activation and cancellation, and latent execution infrastructure. Designers compose those pieces into Blueprint graphs for the needs of their game.

Presentation reacts to state

The actor and visual layer consume render state produced by the simulation. Animation, effects, audio, and presentation telemetry remain downstream and cannot write back into authoritative state.