Pressure plate trigger that activates when enough weight is on it

Pattern: BoxCollision trigger, variable OverlappingActors(int)=0. OnBeginOverlap: OverlappingActors++ → Branch(OverlappingActors >= RequiredCount) → Activate. OnEndOverlap: OverlappingActors-- → Branch(OverlappingActors < RequiredCount) → Deactivate. Use interface or event dispatcher to notify connected actors (doors, platforms).

Elevator or moving platform with timeline and trigger

Pattern: Variables StartLocation(Vector), EndLocation(Vector). BeginPlay: SET StartLocation=GetActorLocation. Timeline MoveTimeline(Alpha 0→1 over Duration). Trigger overlap/button press → Play Timeline. Timeline Update: VLerp(StartLocation, EndLocation, Alpha) → SetActorLocation(Self, Result, bSweep=true). Finished: Delay → Reverse Timeline.

EnhancedInputAction — Enhanced Input system action event

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

Overlap trigger: detect player entering a zone and do something once

Pattern: EventActorBeginOverlap → CastTo<BP_Character>(Object=OtherActor) → Cast Succeeded → DoOnce → [your action here]. Key pins: EventActorBeginOverlap outputs 'OverlappedActor' and 'OtherActor'. CastTo input is 'Object', exec outputs are 'Cast Succeeded' and 'Cast Failed'. DoOnce exec output is 'Completed'.

DoOnce

Lets execution through once, then blocks subsequent attempts until Reset is called. Useful for one-shot triggers.

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.

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.

RetriggerableDelay — delay that resets if triggered again

UKismetSystemLibrary::RetriggerableDelay. Latent.

Checkpoint and autosave system with trigger volumes

Pattern: BP_Checkpoint with BoxTrigger, variable CheckpointID(int). OnBeginOverlap(Player) → DoOnce → CreateSaveGameObject(MySaveGame) → SET PlayerLocation, Health, Inventory, CheckpointID → SaveGameToSlot('AutoSave', 0). On death/respawn: LoadGameFromSlot('AutoSave') → Cast → TeleportTo(SavedLocation) → restore Health etc. Show 'Checkpoint Reached' UI briefly.

Create a Blueprint for a door that opens when the player overlaps a trigger and closes when they leave