Level transition with loading screen

Pattern: CreateWidget(WBP_LoadingScreen) → AddToViewport(ZOrder=100) → LoadStreamLevel or OpenLevel(NewMapName). For async: AsyncLoadLevel → OnCompleted → RemoveFromParent(LoadingWidget). Store persistent data in GameInstance before transition. Use Seamless Travel for multiplayer.

State Machine

A graph of animation states connected by transitions. Each state plays a sequence/blend; transitions fire on rule conditions.

Level transition: save data then open new level

Pattern: custom trigger or UI button → [save player data to SaveSlot] → OpenLevel(LevelName='Level_02', bAbsolute=true, Options=''). For loading screen: SetGlobalTimeDilation(0.001) briefly while level loads (freeze world), or use AsyncLoadLevel with progress callback. Key: OpenLevel is in GameplayStatics. 'LevelName' is the map asset name (not full path). bAbsolute=true discards current level completely. Options string can pass params like '?GameMode=BP_GM'.

Animation Blueprint

An AnimBP — drives Skeletal Mesh animation via a state machine + transition rules. Set AnimClass on the Skeletal Mesh Component.

State machine pattern using enum variable and switch

Variables: CurrentState (your EState enum: Idle, Patrol, Chase, Attack, Dead). EventTick or custom Update event → Switch on EState(CurrentState) → Idle: [idle logic] → Patrol: [patrol logic] → Chase: [chase logic] etc. State transitions via custom events: OnEnemySpotted → SetVariable(CurrentState=EState::Chase). OnEnemyLost → SetVariable(CurrentState=EState::Patrol). OnDamaged → Branch(Health<=0) → True: SetVariable(CurrentState=EState::Dead). Key: Switch On Enum node — connect enum variable to the input, each value gets an exec output pin.

BreakTransform — split Transform into Location, Rotation, Scale

Main menu with widget switching and button navigation

Pattern: WBP_MainMenu with WidgetSwitcher containing panels (Main, Options, Credits). Buttons: OnClicked → SetActiveWidgetIndex(WidgetSwitcher, PanelIndex). Play button: RemoveFromParent → OpenLevel(GameMap). Quit: QuitGame. Level BP BeginPlay: CreateWidget(MainMenu) → AddToViewport → SetInputModeUIOnly → SetShowMouseCursor(true).

BreakTransform — decompose FTransform into location rotation scale

Gate — open/close/toggle flow gate

Macro. Enter only passes through when gate is open.

MakeTransform — create a Transform from Location, Rotation, Scale

Pure node. Essential for SpawnActorFromClass which requires a Transform, not separate Location/Rotation.