How to Make a Door & Interaction System in UE5 Blueprints
The door is the classic interaction-system teaching case because it forces the right architecture: the player shouldn’t know what a door is. The player traces, asks "are you interactable?", and the door handles being a door.
What it’s made of
Variables
On the player: InteractionDistance float. On the door: a bIsOpen bool and a Timeline driving the rotation.
Events
An IA_Interact input fires the trace; a Blueprint Interface (BPI_Interact with an Interact function) is the contract every interactable implements — doors, switches, pickups alike.
The logic
On interact: Line Trace By Channel from the camera forward by InteractionDistance. Does Implement Interface? → call Interact on the hit actor (no casting to specific classes). The door’s Interact flips bIsOpen and plays a Timeline whose float track Lerps the door’s yaw between closed and open — Timeline gives you the curve, reversibility, and interrupt-safety for free.
Key nodes you’ll wire
The mistake that breaks it
Cast To Door in the player. The moment you add a second interactable, casting-per-type collapses — the interface IS the system.
New to how Blueprint systems fit together? Read the anatomy of a Blueprint system first.
Or skip the wiring — generate it
BlueprintStudio builds this system from a plain-language prompt — the right nodes, exec and data pins wired, defaults set, and the graph compiled to catch errors — then applies it into your open UE5 editor. The prompt is prefilled:
Build “Door & Interaction System” in BlueprintStudioPrompt variations to try
Applying into your editor happens through the free Cosindra desktop app (Windows & macOS).