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Cell Junction Filler

Base:
interface
Type:
INCellJunctionFiller / UNCellJunctionFiller
Header File:
NexusWorldAssembly/Public/Cell/INCellJunctionFiller.h

Implemented by actors that are spawned to fill a junction left unconnected at the end of generation. When a junction has no neighbour attached, it selects one of its Fillers entries (or the project-wide Junction Default Filler) and spawns it to cap the opening. The freshly spawned actor is then handed the junction it fills through OnInitializedFromJunction, letting it size or configure itself to match.

Any actor assigned to a junction's Fillers array, or set as the project-wide Junction Default Filler (see Project Settings), must implement this interface — the assignment fields enforce it via MustImplement.

What It Is​

  • Fill Hook: Defines the single callback the junction calls into immediately after spawning the filler actor.
  • Junction Context Bridge: Hands the implementing actor the owning ANCellLevelInstance, the UNCellJunctionComponent being filled, and the filled junction's link identifier.
  • Opt-In Contract: Only actors implementing the interface can be selected as fillers; the editor fields will not accept anything else.

Callback​

/**
 * Called on a freshly spawned filler actor immediately after it is placed at a junction, letting it size or
 * configure itself from the junction it fills.
 * @param CellLevelInstance The cell level instance that owns the junction being filled.
 * @param JunctionComponent The junction this actor was spawned to fill.
 * @param JunctionIndex The filled junction's link instance identifier (LinkDetails.JunctionInstanceIdentifier).
 */
UFUNCTION(BlueprintNativeEvent, CallInEditor, Category="NEXUS|World Assembly")
void OnInitializedFromJunction(ANCellLevelInstance* CellLevelInstance, UNCellJunctionComponent* JunctionComponent, int32 JunctionIndex);

Selection​

At fill time the owning cell filters the junction's Fillers down to the entries whose Required Context Tags and Tag Counter Constraints are satisfied by the cell's final assembly state, then picks one weighted-at-random from the survivors. If every entry is gated out, the project-wide Junction Default Filler is used as the fallback. See Junction Component → Fillers for the authoring surface.