Home › System plugins › AFS_Core_Loading

System

AFS_Core_Loading

Level flow: the level data asset, game mode, transition actors, player start positions and the libraries that switch levels in editor, listen-server and client contexts.

What it gives you

One data asset describing a level's game mode, pawns and maps
Correct level switching in editor, on a listen server and on clients
Customisable loading transitions
Indexed player start positions for multiplayer

Requires

AFM_CameraFade AFM_Teleport AFS_UI

Required by

AFE_Showroom AFU_Intro

12 assets39 API members

Description

PDA_Level is the centre of this plugin. It names the game mode, the pawn class per platform, the persistent map, any streaming maps, the transition actor and a minimum transition time. Because the pawn decision lives here rather than in the map, the same map can serve VR, desktop and mobile.

ML_Loading.Loading_SwitchLevel handles the three cases that usually get written three times: in the editor it fades and calls OpenLevel; with authority it fades every player and issues a servertravel; on a client it fades and opens locally.

FL_Loading caches the active level data asset in the object registry subsystem, so any Blueprint can ask what level it is in without a hard reference.

Setup

See Create a new level for the full walkthrough.

Create a PDA_Level and fill in the game mode, pawn classes and maps.
Place a BP_MapInfo actor in the map pointing at the data asset.
Place BP_PlayerPosition actors as spawn points; mark one Default Position.

Usage

Switching level

Call ML_Loading.Loading_SwitchLevel with the target PDA_Level. Pass Listen Server true when the host should stay listening.

Customising the loading screen

Derive from BP_Transition, override StartLoading and LoadingFinished, and set your class as Transition Class on the level data asset.

Finding the current level

Call FL_Loading.getLevelInfo from anywhere.

Key properties

Property When to change

Pawn Select Force Desktop while iterating; Dynamic for shipping

Min Transition Time Raise to avoid a jarring flash when loading is fast

Streaming Maps Fill only when you actually stream; a non-empty list triggers the loading transition

Player Index / Default Position On BP_PlayerPosition, for multiplayer spawn assignment

Property	When to change
`Pawn Select`	Force Desktop while iterating; Dynamic for shipping
`Min Transition Time`	Raise to avoid a jarring flash when loading is fast
`Streaming Maps`	Fill only when you actually stream; a non-empty list triggers the loading transition
`Player Index` / `Default Position`	On `BP_PlayerPosition`, for multiplayer spawn assignment

Extending

Derive from BP_Transition for custom loading visuals, and implement BPI_PlayerPosition to make your own actor a valid spawn point.

Multiplayer notes

Multiplayer

Level switching on a listen server uses servertravel so all clients follow. bUseSeamlessTravel is enabled on the shipped game mode.

Example map

Map_Examples_Lobby switches between every other example map using this system.

Troubleshooting

The wrong pawn spawns. Pawn Select is set to a Force option, or the map has no BP_MapInfo.

Level switch does nothing in the editor. The editor path strips the play-in-editor prefix via getLevelPathFromReference; a manually built travel URL will not.

API reference

Every blueprint asset in this plugin. Expand an asset to see its members.

Blueprints/MapInfo

BP_MapInfo1 members

extends Actor

Kind	Name	Signature	Description
var	`LevelKey`Info	`PDA_Level`	The level data asset describing this map. Place one Map Info actor per level so any Blueprint can discover the level's configuration.

Blueprints/PlayerPosition

BP_PlayerPosition7 members

extends PlayerStart · implements BPI_PlayerPosition

Kind	Name	Signature	Description
var	`PlayerIndex`Parameter	`int`	Which player this start position belongs to. Positions are claimed in order, so give each start a distinct index for multiplayer.
var	`DefaultPosition`Parameter	`bool`	Marks this as the fallback start used when no position matches the joining player's index.
var	`Use Fade`Settings	`E_Teleport_Fade`	Whether teleporting a player to this position fades the camera.
fn	`FindFreeIndex`Parameter	`()`	Claims the next unused player index for this position.
event	`OnTeleportFinished_Event`	`(Pawn: Pawn)`	Internal handler fired once a pawn has finished teleporting to this position.
event	`PlayerPosition_TeleportToPosition`	`(Pawn: Pawn)`	Teleports the given pawn to this start position.
event	`PlayerPosition_PawnSpawnedHere`	`(Pawn: Pawn)`	Called when a pawn spawns at this position, so the start can run any arrival logic.

Blueprints/Transition

BP_Transition2 members

extends Actor

Kind	Name	Signature	Description
event	`LoadingFinished`	`()`	Called when loading completes and the minimum transition time has elapsed. Override to dismiss your loading visuals.
event	`StartLoading`	`()`	Called when loading begins. Override in a subclass to show your own loading visuals.

BP_Transition_Default2 members

extends BP_Transition

Kind	Name	Signature	Description
event	`LoadingFinished`	`()`	Fades out the default loading screen and destroys the transition actor.
event	`StartLoading`	`()`	Shows the default loading screen and begins its animation.

DataAssets

PDA_Level11 members

extends PrimaryDataAsset

Kind	Name	Signature	Description
var	`GameMode`Pawn	`Class<GameMode>`	Game mode loaded with this level. Passed on the travel URL so it applies to networked travel as well.
var	`PawnSelect`Pawn	`E_Pawn_Select`	How the pawn is chosen. Dynamic detects VR, then mobile, then desktop; the Force options override that for testing.
var	`Default_Pawn_Desktop`Pawn	`Class<Pawn>`	Pawn class possessed when the level is entered on a desktop machine. Only consulted when Pawn Select resolves to desktop; leave it empty and the level loads with no pawn on that platform.
var	`Default_Pawn_VR`Pawn	`Class<Pawn>`	Pawn class spawned when a head-mounted display is present.
var	`Default_Pawn_Mobile`Pawn	`Class<Pawn>`	Pawn class spawned on iOS and Android.
var	`Name`Information	`text`	Display name for this level, shown in navigation and loading UI.
var	`TransitionClass`Transition	`Class<BP_Transition>`	Transition actor spawned while streaming maps load. Subclass it to customise the loading screen.
var	`MinTransitionTime`Transition	`float`	Shortest time the loading screen stays up, in seconds. Prevents a jarring flash when loading is fast.
var	`PersistantMap`Streaming Level	`SoftWorldReference`	The map opened immediately when switching to this level.
var	`StreamingMaps`Streaming Level	`SoftWorldReference[]`	Maps streamed in after the persistent map opens. If this list is non-empty a loading transition is shown while they load.
fn	`getPawnToSpawn`	`(out PawnToSpawn: Class<Pawn>)`	Resolves which pawn class to spawn, applying the Pawn Select rule against the current platform.

Game

BP_GameMode0 members

extends GameMode

No editor-visible members; this asset configures defaults only.

Helper

BP_Helper_Pawn_Loading8 members

extends Pawn

Kind	Name	Signature	Description
fn	`RequiresLoading`	`(out RequiresLoading: bool)`	Returns whether this level still has streaming maps to load before gameplay can begin.
fn	`FindStartingPlayerPosition`	`(PlayerIndex: int, out PlayerPosition: Actor)`	Finds the player start matching the given index, falling back to the default position.
event	`Server_ControllerReady`	`(Controller: PlayerController)`	Tells the server this client's controller is ready, so the real pawn can be spawned.
event	`Client_LoadLevels`	`(Level: PDA_Level)`	Instructs this client to stream in the level's maps and show the transition while it happens.
event	`ControllerChanged`	`(OldController: Controller, NewController: Controller)`	Internal handler that reacts to this placeholder pawn being possessed or unpossessed.
event	`Server_LoadLevelInfo`	`()`	Asks the server for the level data asset so the client knows what to load.
event	`CheckForUnpossess`	`(Controller: Controller)`	Checks whether this placeholder pawn is still needed and destroys it once the real pawn has taken over.
event	`Server_DestroyPawn`	`()`	Asks the server to destroy this placeholder pawn.

Interfaces

BPI_PlayerPosition5 members

extends Interface

Kind	Name	Signature	Description
fn	`PlayerPosition_getSpawnTransform`Player Position	`(out Transform: Transform)`	Returns the transform a pawn should spawn at for this position.
fn	`PlayerPosition_getIndex`Player Position	`(out Index: int)`	Returns the player index this position is reserved for.
fn	`PlayerPosition_IsDefault`Player Position	`(out Default: bool)`	Returns whether this is the fallback position used when no index matches.
fn	`PlayerPosition_TeleportToPosition`Player Position	`(Pawn: Pawn)`	Teleports the given pawn to this position.
fn	`PlayerPosition_PawnSpawnedHere`Player Position	`(Pawn: Pawn)`	Notifies the position that a pawn has spawned there.

Libraries

FL_Loading3 members

extends BlueprintFunctionLibrary

Kind	Name	Signature	Description
fn	`getLevelInfo`LevelInfo	`(const Context: Object, __WorldContext: Object, out Level: PDA_Level)`	Returns the level data asset for the current level, reading it from the object registry and falling back to the Map Info actor placed in the map.
fn	`setLevelInfo`Level Info	`(Context: Object, Level: PDA_Level, __WorldContext: Object)`	Stores the level data asset in the object registry so later lookups avoid searching the level.
fn	`getLevelPathFromReference`Level	`(const Level: SoftObject<World>, __WorldContext: Object, out LevelPath: name)`	Converts a soft world reference into a travel path, stripping the editor play-in-editor prefix so server travel works from the editor.

ML_Comp_Loading0 members

extends ActorComponent

No editor-visible members; this asset configures defaults only.

ML_Loading0 members

extends Actor

No editor-visible members; this asset configures defaults only.

Widgets

WBP_Loading0 members

extends WBP_Base

No editor-visible members; this asset configures defaults only.