Multiplayer POC godot

A Godot 4 multiplayer reference implementation. Originally created for Dank Nooner, this repo serves as a learning resource and code reference for anyone implementing multiplayer in Godot 4.

This project focuses on core networking concepts including:

• Client-server architecture using Godot's high-level multiplayer API
• Player synchronization and state management
• Network optimization and performance testing
• Connection handling and error recovery

Feel free to use this as a reference or starting point for your own Godot 4 multiplayer projects.

See TODO.md for progress.

Builds

• Download the latest build in releases
  • NOTE: This may not be fully up-to-date, try using godot to compile the project yourself!

Demo (gif)

Architecture

Click to view the Flow Diagram.

Server Authority

Once a player launches the game & selects "Host Game", they are the "server"

Lobby

• ENet server is started & listening for connections, callbacks signals are connected. (on_peer_connected, etc.)
• On connection:
  • Add connected player id (int) to the lobby list.
  • RPC to all to send "player connected" in chat. (Using text_chat_ui)
• On disconnection:
  • Same as "on connection", but "disconnect" instead.
  • queue_free() that player on all clients
• On "start game" pressed (only on host pc):
  • RPC to all:
    • Hide lobby ui
    • Instantiate the level & add node to scene tree
    • Set MultiplayerManager spawn nodes from level (needed for MultiplayerSpawner to sync spawns)
    • Spawn all players from lobby list
  • On the server only:
    • Start enemy spawn timer

In Game

• Listen for input from InputSynchronizer
  • Apply movement vector from MultiplayerSynchronizer (wasd => move_and_slide())
  • If shoot_bullet() is called, spawn the bullet & shoot it locally
  • If play_rotate_anim() is called, play the animation locally
• Enemy AI
  • Collision detection w/ player, if hit player RPC to server & call die()
  • Navigation (to closest player), runs on a timer, server sets position

Text Chat (text_chat_ui)

• Client types msg, when pressing enter:
  • RPC to all with message + ID of sender
  • Clients render the msg
  • If show_player_connected() (or disconnected) is called as rpc, create UI Label / render

Client Authority

• InputSynchronizer gets multiplayer authority for the local client
• In _physics_process():
  • Listen for movement input as a vector & save to MultiplayerSynchronizer's var (input_dir)
  • Listen for shoot / rotate Inputs, when used:
    • RPC call to server
• Typing / sending text chat to all peers
• Playing animations, spawning/despawning the nodes themselves (from MultiplayerSpawner on server)

License

AGPL