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02 — Quick Start

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One complete example: a desktop character picks up an item, throws it and opens a door. After every step you can see the result. Step-by-step exercises with explanations are in 14 — Step-by-step tutorials.

Steps

  1. Enable Edit → Plugins → InteractionSystem in a UE 5.8 project and restart the editor.

Result: InteractorComponent appears in Components → Add.

  1. In the character Blueprint enable Replicates and add an InteractorComponent, attaching it to the camera. Keep Use Pawn Viewpoint on: the source will use the controller's current view point.

Result: in the components window the source sits under the camera.

  1. Create a Blueprint from InteractionMasterItem. Assign Mesh Component a static mesh with simple collision that responds with Block on the Visibility channel. Place the item in front of the camera within 300 cm.

Result: in the game a small dot appears near the item, and E appears when you aim at it.

  1. In your input mapping bind one action to Request Grab and another to Request Release. To release without a throw, pass zero vectors; to throw, pass a velocity in cm/s and an angular velocity in degrees/s.

Result: after the first action the item ends up in front of the camera; the second action releases or throws it.

  1. For a door or a button implement Interaction and call Request Interaction instead of Request Grab. The ready-made physics actor also has a server event On Interacted. A step-by-step example of a door that every player sees is lesson 2.

Result: the door reacts to the press.

E is only the initial prompt text. Change Interaction Prompt or assign a texture to Focus Icon → Sprite to match your keys. The plugin does not add keys by itself.

In plain words. Aiming is only "pointing a finger". The item gets into your hand when the server agrees: in single-player that is instant, in multiplayer it takes a server round trip.

If something does not work

Type InteractionOverlay in the game console. A panel appears on the right: whether the source sees an item (Focus), the state of the hand (State) and what the server answered (Last answer). The explanation is in 15 — Debug tools.

Ready-made example

In the Content Browser enable Show Plugin Content and open /InteractionSystem/Demo/InteractionLab/Maps/InteractionLab. Move with WASD, look with the mouse, E grabs or uses the door, F throws. The demo character creates its own Enhanced Input in code and does not change your project's settings.

In a C++ module add InteractionSystem to the dependencies; for ready-made items also InteractionSystemWorld (12).

What next

  • Seven step-by-step lessons from the first item to network debugging — 14.
  • Character with Enhanced Input, HUD prompts, doors and VR hands in Blueprint — 11.
  • The same in C++, a custom grab target and the server-side manipulation functions — 12.
  • How the server validates requests and why an action can be rejected — 13.
  • What to know before integrating — Limitations and known issues.