ShoryuNet

ShoryuNet is a P2P UDP rollback netcode library written in C#, intended to be used for fighting games. It supports multiple remote players and spectators.

Usage

1. Build the project and import ShoryuNet.dll in your own project
2. Create a Callbacks struct and assign a callback to each delegate (see the Callbacks section for more details)
3. Create a ShoryuBackend object. A ShoryuBackend requires the following arguments:
   • The local port on which ShoryuBackend should send and receive messages (must range between 1024 and 65535)
   • The length of the input packets (this must be equal across all peers)
   • The aforementioned Callbacks struct
   • A PlayerType saying whether you are a Local player or a Spectator
   • The id byte of the local player
   • Optional: How many milliseconds reading packets needs to be delayed by to simulate latency
   • Optional: Every X packets that gets dropped to simulate packet loss
4. Call Connect() using the IPEndPoint of another peer
5. Call Start() to start the game
6. Make sure that in your update loop AddInput(byte[] inputs) is called with the inputs for this state as an argument, and that SyncInput() is called after

Example:

void EventCallback(ClientState state) {
	// Do something after the state of ShoryuBackend has changed
	...
}

void LoadState(int frame, byte[] inputs) {
	// Roll the state of the game back using the inputs given by ShoryuBackend
	...
}

Callbacks cb = new Callbacks();
cb.EventCallback += EventCallback;
cb.LoadState += LoadState;

ShoryuBackend session = new ShoryuBackend(11000, 3, cb, PlayerType.Local, 0);

session.Connect(new IPEndPoint(IPAddress.Parse("IP address of peer"), 1024);
session.Start()

void Update() {
	byte[] inputs = new byte[3];
	// Game related operations
	...
	
	session.AddInput(inputs);
	byte[] allPlayerInputs = session.SyncInput();
}

Callbacks

Periodically ShoryuNet will call back the host program to alert it about changes or that you should roll back. These callbacks are as follows:

• DebugOutput(string output): Prints debug info and current information about what ShoryuNet is doing, like what packets were received and sent, etc.
• LoadState(int frame, byte[] inputs): Returns the framecount and the inputs for all players on that frame, which the host program should resimulate.
• EventCallback(ClientState state): Returns the current state of ShoryuBackend (i.e. NotConnected, WaitingForGameStart, InGame, etc.) when it changes.