Game Initialization

The GameMode initializes when a World is loaded. The World Settings defines the GameMode to use and (in Lyra) which Lyra Experience to load by default.

There are different ways a World can come to be loaded, including clicking the “Play In Editor” (PIE) button.

As discussed in more detail in Lyra Experience, unlike other Games, in Lyra you must ensure to delay all game play until OnExperienceLoaded, perhaps long after BeginPlay.

World Load Procedure

World Loading follows this procedure:

• Initialize Components of all World Actors
  • Init Game Mode
  • Initialize Components (random Actor order)
  • Player Login
    • Create Player Controller & Player State
• World Begin Play
  • Begin Play on all World Actors (random Actor order)
• Load Lyra Experience
  • OnExperienceLoaded signals that game play can begin

Initialize Components of all World Actors

This is implemented by World🡒InitializeActorsForPlay

Init Game Mode

• GameMode🡒InitGame

Initialize Components

Initialization of World Actors is in RANDOM ORDER.

When the GameMode is initialized, it does:

• GameMode🡒PreInitializeComponents
  • GameState🡒PreInitializeComponents
  • GameState🡒PostInitializeComponents
  • GameMode🡒InitGameState
• GameMode🡒PostInitializeComponents

Player Login

• GameMode🡒Login
  • GameMode🡒SpawnPlayerController
    • PlayerController🡒PreInitializeComponents
    • PlayerController🡒PostInitializeComponents
      • PlayerController🡒InitPlayerState
        • PlayerState🡒PreInitializeComponents
        • PlayerState🡒PostInitializeComponents
          • GameState🡒AddPlayerState
        • PlayerController->OnPlayerStateChanged
      • PlayerController🡒AddCheats
  • GameMode🡒InitNewPlayer
• PlayerController🡒SetPlayer
  • PlayerController🡒SetupInputComponent
  • PlayerController🡒ReceivedPlayer
    • CommonGame adds root HUD layout
• GameMode🡒OnPostLogin

World BeginPlay

• All World Subsystems OnWorldBeginPlay
• GameMode🡒StartPlay
  • GameState🡒HandleBeginPlay
    • PlayerController🡒PushInputComponent
    • All World Actors BeginPlay (RANDOM ORDER)
      • GameMode🡒BeginPlay
      • GameState🡒BeginPlay
      • PlayerController🡒BeginPlay
      • PlayerState🡒BeginPlay
      • … etc …

Load Lyra Experience

In PIE, the World’s Default Lyra Experience gets loaded on the tick after GameMode🡒InitGame.

In Game, the appropriate Lyra Experience is loaded by the Frontend State Component (or your similar Game State Component).

Experience Load Procedure

• Load Experience Asset and its References
• Load all GameFeature Plugin (GFP) dependencies
• Activate GFPs (execute GameFeature Actions)
• Broadcast OnExperienceLoaded

For full details, see Experience Loading Procedure