Interactable interface system with line trace from camera

Pattern: BPI_Interactable interface with Interact(APawn* Caller) and GetInteractText(). Player Tick: GetPlayerCameraManager → GetCameraLocation/Rotation → LineTraceSingle(CamLoc, CamLoc + Forward*InteractDistance) → BreakHitResult → HitActor → DoesImplementInterface(BPI_Interactable) → True: show UI prompt, store as FocusedActor. Interact input → call Interact(Self) on FocusedActor.

Line trace raycast for interaction system

Pattern: Input trigger → LineTraceSingle(CameraLocation, CameraLocation + ForwardVector * Distance, Visibility, false, MakeArray(Self), None) → Branch(ReturnValue) → True: BreakHitResult → HitActor → CastTo InteractableInterface → call Interact. End pin is world POSITION not direction. Use DrawDebugType ForOneFrame during dev.

EnhancedInputAction — Enhanced Input system action event

K2Node_EnhancedInputAction. ActionValue type depends on InputAction (Bool, Float, Axis2D, Axis3D). Triggers: Started, Ongoing, Triggered, Completed, Canceled.

EnableInput — allow this actor to receive input events

Must call EnableInput(GetPlayerController(0)) before BindAction/BindAxis events fire on the actor.

PlayMontage — play an AnimMontage on a SkeletalMeshComponent

Call on the SkeletalMeshComponent. Get it via GetMesh() on Character. Returns montage length. Exec out is 'then'.

Pickup and collectible system with overlap trigger

Pattern: Pickup actor with SphereCollision(overlap), StaticMesh visual. OnComponentBeginOverlap → CastTo PlayerCharacter → Success: call AddScore/AddItem interface on player → PlaySoundAtLocation → SpawnEmitterAtLocation → DestroyActor(self). Set collision to OverlapOnlyPawn for performance.

SetCollisionEnabled — enable, disable or set query-only collision

ECollisionEnabled values: NoCollision, QueryOnly, PhysicsOnly, QueryAndPhysics.

PlayAnimation (widget) — play a Widget Animation

Event dispatcher pattern for decoupled communication between actors

Pattern: Actor A declares EventDispatcher OnScoreChanged(int NewScore). Actor B (listener) BeginPlay: GetActorOfClass(A) → BindEvent(OnScoreChanged) → custom event handler. Actor A calls OnScoreChanged.Broadcast(Score) when score changes. Bind in BeginPlay, Unbind in EndPlay to avoid dangling references.

OnHit

Fires when a physics collision happens. Use for impact effects, damage on contact.