Show UI widget on key press, hide on key press again (toggle)

Variables: MenuWidget (UserWidget subclass), bIsMenuOpen (bool). InputAction MenuKey → FlipFlop → A (open): Branch(MenuWidget is null) → True: CreateWidget(WBP_Menu) → SetVariable(MenuWidget) → AddToViewport → SetInputMode_UIOnly → SetShowMouseCursor(true) → SetVariable(bIsMenuOpen=true). B (close): MenuWidget → RemoveFromParent → SetInputMode_GameOnly → SetShowMouseCursor(false) → SetVariable(bIsMenuOpen=false). Key: Always check IsValid(MenuWidget) before calling RemoveFromParent. SetInputMode_UIOnly is on PlayerController. Don't re-create widget if it exists — just show/hide.

Flip-Flop

Alternates between A and B output pins on each execution. Useful for toggle switches and ping-pong logic.

Gate — open/close/toggle flow gate

Macro. Enter only passes through when gate is open.

SetVisibility widget — show or hide widget

ESlateVisibility: Visible, Collapsed, Hidden, HitTestInvisible, SelfHitTestInvisible.

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).

SetVisibility — show or hide a scene component

Door open and close with timeline and trigger volume

Pattern: Door actor with BoxTrigger, DoorMesh, Timeline(Alpha 0→1 over 1s). BeginOverlap → PlayFromStart(Timeline). EndOverlap → Reverse(Timeline). Timeline Update: Lerp(ClosedRotation, OpenRotation, Alpha) → SetRelativeRotation(DoorMesh). For sliding: Lerp locations instead of rotations.

SetVisibility on component — show or hide a scene component

SetInputMode UIOnly — give all input to UI (show cursor)

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.