MultiplayerSeatingSystem (UE5 C++)

A high-performance, server-authoritative, and modular seating plugin for Unreal Engine 5. Includes late-joiner synchronization, dedicated server support, and a decoupled component-based architecture. This plugin provides a "plug-and-play" solution to handle replicated character-to-object interactions.

🚀 Key Features

• Server-Authoritative Interaction: Full validation on the server to prevent "teleport-sitting" and distance-based exploits.
• Late-Joiner Correctness: Uses state-based replication (Atomic Structs + OnRep) ensuring players who join mid-session see the correct world state.
• Component-Based Architecture: Decoupled logic allows you to add seating to ANY actor (Chairs, Couches, Vehicles, Horses) without inheritance bloating.
• Deterministic Contention Handling: Gracefully handles "race conditions" where multiple players attempt to sit in the same slot simultaneously.
• Event-Driven Cleanup: Automatic slot freeing via OnDestroyed delegates for disconnected players or destroyed objects.
• UI/UX Integrated: Includes a C++ driven interaction prompt system that intelligently detects the closest available slot.

🛠 Technical Breakdown

Replication Strategy

This system avoids unreliable Multicast RPCs. Instead, it uses a replicated Atomic Struct (FSittingState) containing the Seatable reference, Slot Index, and State. This ensures that all data required for the client to render the "Sitting" state arrives in a single packet, preventing visual glitches.

📖 Installation & Quick start setup

1. Add the MultiplayerSeatingSystem folder into your project's Plugins/ folder.

2. Add "ModularSeatingSystem" to your .Build.cs dependencies.

3. Regenerate project files and compile.

4. The Seatable: Add USeatableObjectComponent to any Actor. Place SceneComponents (for example UArrowComponents) for seat slots in your viewport and register them with the component.

5. The User: Add UCharacterSeatingComponent to your Pawn.

6. Interaction: Call the Interact() function from your Input Action. This handles both sitting on the actor in the closest slot, and standing up if already sitting. There's also RequestSit(AActor* TargetSeatable, int32 DesiredSlotIndex = -1) exposed for sitting at desired seat slot, and RequestStand() for standing up.

7. For states handling (for example animations), the component is exposing "IsSitting()" function which returns true after assigning the seat slot.