Zones and Interactables

These classes deal with where players spawn, moving players between zones and proxies, and the optional interactable framework. For the concepts, see Zones, Sharding, and Instanced Dungeons.

ARedwoodZoneSpawn

An actor you place in your levels to mark spawn points for a zone. It shows as a billboard with a red arrow in the editor.

Property / function	Type	Default	Meaning
ZoneName	FString	empty	The zone this spawn belongs to. Must match a zone key in the game profile's zones (e.g. town, or main for single-zone profiles).
SpawnName	FString	default	Name used by TravelPlayerToZoneSpawnName. Each zone should have one spawn named default, used when a player has no saved location in that zone.
SpawnRadius	float	0	Randomly offset the spawn position within this radius.
bRandomizeRotation	bool	false	Use a random yaw.
GetSpawnTransform()	FTransform		The transform a player would spawn at. Redwood traces down (and then from 1000 units above) against WorldStatic to find the ground, then adds 100 units of height.

A single map can contain spawns for several zones (for example, when the same overworld map is used by the town and wilds zones). Only spawns whose ZoneName matches the server's zone are used. See Spawn Selection for the full order of precedence.

tip

A zone can have more than one named spawn, for example default, from-cave, and from-dungeon, so players returning from different places appear in the right spot.

Zone Transfers

Zone transfers move a connected player from their current server to a server for another zone (or another proxy). They're functions on URedwoodServerGameSubsystem, so call them on the server (get the subsystem from the game instance).

Function	Parameters	Meaning
TravelPlayerToZoneSpawnName	PlayerController, InZoneName, InSpawnName = "default", OptionalProxyId = ""	Send the player to the ARedwoodZoneSpawn named InSpawnName in zone InZoneName.
TravelPlayerToZoneTransform	PlayerController, InZoneName, InTransform, OptionalProxyId = "", bShouldStitch = false	Send the player to zone InZoneName at InTransform (location and rotation; the player's control rotation is kept). Use this for seamless boundaries, so the player appears at the same spot on the other side. Leave bShouldStitch as false (it's for an unreleased feature).

OptionalProxyId targets a different proxy (for example a specific instanced dungeon, or the parent overworld). Leave it empty to stay in the current proxy.

What happens:

1. Redwood marks the player as transferring and asks the sidecar to transfer them.
2. The Realm saves the destination as the character's last location, starts (or finds) a server for the target zone, and tells the player's client to connect to it.
3. The client travels automatically (or fires OnRequestToJoinServer if bAutoConnectToServers is off).
4. When the player leaves the old server, their data is saved, without overwriting the new location.
5. On the new server, spawn selection uses the saved location.

If the transfer fails, the player is kicked with the error message. Zone transfers require the backend; in no-backend mode they log an error.

note

Only players transfer. Moving sync items between zones isn't supported.

Portal Content

RedwoodCore includes Blueprint content in /RedwoodCore/Zones/Portal/ (enable Show Plugin Content in the Content Browser) for seamless zone boundaries in a map shared by two zones.

Asset	What it is
B_PortalSpline	An actor with a spline. On the server, it builds a wall of B_PortalComponent segments along the spline. Set RedSideZone and GreenSideZone to the zone names on each side, and BoxSize/BoxWidth to size the segments.
B_PortalComponent	One segment: trigger boxes and visual walls for each side. When a player's character leaves a box toward the other zone, it calls TravelPlayerToZoneTransform with the player's current position, so they continue walking from the same spot on the other zone's server. It ignores transfers to the zone the server already runs.
M_PortalGate, MI_PortalGate*	Materials that show the wall as an entrance or exit depending on which zone the server runs.

To use it:

1. Make sure the map is used by both zones in your game profile (e.g. town and wilds both list the overworld map).
2. Place a B_PortalSpline along the boundary and shape the spline.
3. Set RedSideZone and GreenSideZone to the two zone names.
4. Set syncItemsFromZones on each zone if players should see items from across the boundary.

These are Blueprints, so you can duplicate and modify them (for example, to change the look or add a loading screen).

Interactables

An optional framework for things players interact with (pickups, doors, NPCs, zone transfer triggers). It keeps the server RPC in one place (on the player's pawn) instead of on every interactable. You don't have to use it.

ARedwoodInteractable

A replicated actor with a SphereComponent (collision profile OverlapOnlyPawn) that defines the interaction area.

Member	Type	Default	Meaning
SphereComponent	USphereComponent*		The interaction area. Resize it in your subclass.
bAutoInteract	bool (replicated)	false	Interact automatically when a pawn with a URedwoodInteractComponent overlaps it (e.g. walking into a coin).
OnInteract(Pawn, CharacterComponent)	BlueprintNativeEvent		Override this. Called on the server when a player interacts. CharacterComponent is the pawn's URedwoodCharacterComponent, so you can change and Mark...Dirty their data.

Interactables also respond to the Redwood.Player.Interaction gameplay message: if the message's pawn overlaps the sphere and has a character component, OnInteract is called.

ARedwoodInteractableProxied

A subclass whose OnInteract spawns an actor of ProxyClass (a subclass of ARedwoodProxy) owned by the interacting pawn, and sets its Interactable to this actor. Use it when an interaction opens per-player state, like a merchant or bank UI, that only that player should see.

Member	Type	Meaning
ProxyClass	TSubclassOf<ARedwoodProxy>	The actor to spawn for the interacting player

ARedwoodProxy

A replicated actor that's only relevant to its owner (bOnlyRelevantToOwner = true). Its Interactable property (replicated, read only) points back at the interactable that spawned it. Put the per-player logic and RPCs for an interaction here. (This is unrelated to the backend's GameServerProxy.)

URedwoodInteractComponent

A replicated component for the player's pawn. The pawn's root component must be a shape component (e.g. an ACharacter capsule). It isn't directly spawnable, so create a Blueprint subclass of it and add that to your pawn.

Member	Meaning
OnInteractionAvailability(bAvailable)	BlueprintNativeEvent, called on the locally controlled client when an interactable comes into or out of range. Use it to show an "interact" prompt.
GetInteractables()	The ARedwoodInteractable actors currently overlapping the pawn.
CanInteract()	Whether any interactable is in range.
RPC_Interact()	Server RPC. Call it from your input handling on the client; the server picks an interactable with PickInteractable and calls its OnInteract. The pawn needs a URedwoodCharacterComponent.
PickInteractable(Interactables)	BlueprintNativeEvent that chooses which interactable to use when several overlap. Defaults to the first one. Override it to pick the closest, for example.

A typical setup:

1. Create B_InteractComponent (child of URedwoodInteractComponent) and add it to your character.
2. In your character, on the interact input action, call RPC_Interact on the component.
3. Create interactables as children of ARedwoodInteractable and implement On Interact.

For example, a zone transfer trigger is an interactable whose On Interact calls TravelPlayerToZoneSpawnName with the pawn's controller. Because On Interact runs on the server, interactions that need a client API call (like joining matchmaking for an instanced dungeon) should use an ARedwoodInteractableProxied and make the call from a client RPC or replicated event on the spawned ARedwoodProxy.

Known issue (5.0.0)

URedwoodInteractComponent binds its overlap events in BeginPlay only if the pawn is locally controlled at that moment. If your pawn is possessed after BeginPlay on clients, the availability events may not fire.

Running Console Commands on All Clients

URedwoodServerGameSubsystem::CallExecCommandOnAllClients(Command) (server only) spawns an always-relevant, replicated ARedwoodClientExecCommand actor. Each client runs Command as a console command when the actor replicates to it.

Known issue (5.0.0)

These actors are never destroyed, so players who join later also run every previous command, and the actors accumulate. Use it sparingly.