MultiConstructor¶

Vanilla MultiConstructor : Stackable, IConstructionKit, IConstructionStarter, IReferencable, IEvaluable at Assets.Scripts.Objects.MultiConstructor. The held-item kit form for placing one of N prefab variants (rail-kit with 8 pieces, etc.). Sibling to Constructor (single-prefab kit).

Class layout¶

public class MultiConstructor : Stackable, IConstructionKit, IConstructionStarter, IReferencable, IEvaluable
{
    [Header("Multi-Constructable")]
    public List<Structure> Constructables = new List<Structure>();

    [NonSerialized]
    public int LastSelectedIndex;

    public override void OnPrefabLoad()                          // strips null entries from Constructables, clamps LastSelectedIndex
    public virtual void Construct(Grid3, Quaternion, int optionIndex, Item offhandItem, bool authoringMode, ulong, [int quantity])
    public override string GetStationpediaCategory() => Localization.GetInterface(StationpediaCategoryStrings.KitCategory);
    public bool CanBuild(int index)                              // checks Quantity >= Constructables[index].BuildStates[0].Tool.EntryQuantity
    public List<Thing> GetConstructedPrefabs()
}

Constructables is a serialized list of every prefab the kit can place (e.g. all 8 rail variants for the rail-kit). LastSelectedIndex persists which variant the player last picked, so swapping back to the kit reopens on the same option.

Construct¶

Two overloads. The arity-7 form looks up the EntryQuantity for the chosen variant and forwards to the arity-8 form.

public virtual void Construct(Grid3 localPosition, Quaternion targetRotation, int optionIndex, Item offhandItem, bool authoringMode, ulong steamId)
{
    int entryQuantity = Constructables[optionIndex].BuildStates[0].Tool.EntryQuantity;
    Construct(localPosition, targetRotation, optionIndex, offhandItem, authoringMode, steamId, entryQuantity);
}

public virtual void Construct(Grid3 localPosition, Quaternion targetRotation, int optionIndex, Item offhandItem, bool authoringMode, ulong steamId, int quantity)
{
    if (authoringMode || OnUseItem(quantity, null))
    {
        CreateStructureInstance createStructureInstance = new CreateStructureInstance(Constructables[optionIndex], localPosition, targetRotation, steamId);
        if (PaintableMaterial != null && CustomColor.Normal != null)
        {
            createStructureInstance.CustomColor = CustomColor.Index;
        }
        if (GameManager.RunSimulation)
        {
            Constructor.SpawnConstruct(createStructureInstance);
        }
    }
}

Identical Quaternion handling to Constructor.Construct: the incoming targetRotation is stored in CreateStructureInstance.LocalRotation and forwarded to Constructor.SpawnConstruct. Note the asymmetry: MultiConstructor.Construct only calls SpawnConstruct when GameManager.RunSimulation == true, omitting the client-side new ConstructionCreationMessage(...).SendToServer() branch. Multi-kit placement on a remote client therefore relies on the calling code (e.g. InventoryManager.PlacementMode) to dispatch the network message via OnServer.UseMultiConstructor(...) rather than going through this method.

Differences from Constructor¶

Aspect	Constructor	MultiConstructor
Built prefab	One: `BuildStructure`	One of N: `Constructables[optionIndex]`
Per-prefab quantity	`QuantityUsed` (single int field)	`Constructables[i].BuildStates[0].Tool.EntryQuantity` (per-variant)
`OnUsePrimary` override	Yes; calls `Construct(targetLocation.ToGridPosition(), targetRotation, ...)`	None; placement dispatched at the inventory layer
Client network branch in own code	Yes: `new ConstructionCreationMessage(...).SendToServer()`	No; relies on caller
`Constructables` mutation hook	n/a	`OnPrefabLoad` strips nulls, clamps `LastSelectedIndex`

For mod patterns that need to insert a new variant into an existing rail-kit / wall-frame-kit, see Patterns/PrefabCloning.md "AddToConstructor" (the recipe that calls mirrorDef.constructor.Constructables.Insert(insertIndex + 1, mirroredDevice as Structure)).

Verification history¶

2026-04-25: page created from a six-agent decompile pass on the placement pipeline. Source content lifted verbatim from /tmp/decompile_check/Assets/Scripts/Objects/MultiConstructor.cs. No conflicts.

Open questions¶

None.