GarageServer.IO

A simple, lightweight, HTML multiplayer game server (and client) for Node.js

Features

Authoritative Game Server
Client Side / Input Prediciton
Client Side Smooting
Entity Interpolation
Server State History
Server and Client Messaging

Quick Start

Create a quick game whereby players simply move squares along the x-axis. I know, it's boring, but it keeps things simple and to the point. For a more thorough demonstration of how GarageServer.IO works, look at the example included in the source code.

Server

1. Create instance of GarageServer.IO - pass in a Socket.IO instance and GarageServer.IO options.

var garageServer = require('garageserver.io'),

var server = garageServer.createGarageServer(sockets, 
    {
        interpolation: true,
        clientSidePrediction: true,
        worldState: { width: '400px', height: '400px'; }
    });

2. Start GarageServer.IO instance prior to starting physics loop. This starts the clock that is used for broadcasting state and storing state history.

server.start();

3. Inside physics loop, process inputs for players, process entites and update states. Note that state is an object literal effectively offering up any grab bag of properties that pertain to your game's state.

var players = server.getPlayers(),
    entities = server.getEntities();

players.forEach(function (player) {
    var newState = {};
    if (!player.state.x) {
       player.state.x = 0;
    }
    for (i = 0; i < player.inputs.length; i ++) {
        if (player.inputs[i].input === 'left') {
            newState.x = player.state.x - (50 * deltaTime);
        } else if (inputs[i].input === 'right') {
            newState.x = player.state.x + (50 * deltaTime);
        }
    }
    server.updatePlayerState(player.id, newState);
});
entities.forEach(function (entity) {
    // Calculate new state from entity.state and send GarageServer.IO new state
    server.updateEntityState(entity.id, newState);
});

Client

1. Initialize GarageServer.IO.

GarageServerIO.initializeGarageServer('http://insertmygameurlhere.com', {
    onReady: function () {
        // Call your game loop
    },
    onUpdatePlayerPrediction: function (state, inputs, deltaTime) {
        var newState = {};
        if (!player.state.x) {
        player.state.x = 0;
        }
        for (i = 0; i < player.inputs.length; i ++) {
            if (player.inputs[i].input === 'left') {
                newState.x = player.state.x - (50 * deltaTime);
            } else if (inputs[i].input === 'right') {
                newState.x = player.state.x + (50 * deltaTime);
            }
        }
        return newState;
    },
    onInterpolation: function (previousState, targetState, amount) {
        return { x: (previousState.x + amount * (targetState.x - previousState.x)) };
    },
    onWorldState: function (state) {
        document.getElementById('gameCanvas').style.width = state.width;
        document.getElementById('gameCanvas').style.height = state.height;
    }
};

2. Inside physics loop, capture and send input via GarageServer.IO.

GarageServerIO.addInput(myInput);

3. Inside render loop, extract player and entity states.

var playerStates = GarageServerIO.getPlayerStates(),
    entityStates = GarageServerIO.getEntityStates();  
    playerStates.forEach(function (player) {
        ctxCanvas.fillRect(player.state.x, 0, 5, 5);
    });
    entityStates.forEach(function (entity) {
        ctxCanvas.fillRect(entity.state.x, 0, 5, 5);
    });

API

Client

initializeGarageServer

GarageServerIO.initializeGarageServer(path, options)

Establish connection to GarageServer.IO on the server via Socket.IO and register events.
path string
The URL that points to where GarageServer.IO is running at on the server.
options object literal
Configure the different options, events, callbacks that you would like to consume on the client.

Client Options

options.onPlayerConnect(callback)

Once the client has made a connection to the server, this event will fire.
callback function
Function to be invoked upon event firing.

options.onPlayerDisconnect(callback)

If client has has disconnected from the server, this event will fire.
callback function
Function to be invoked upon event firing.

options.onPlayerReconnect(callback)

If client has has disconnects and reconnects to the server, this event will fire.
callback function
Function to be invoked upon event firing.

options.onPlayerUpdate(callback(state))

Event fired each time state is received for a player.
callback function
Function to be invoked upon event firing.
state object literal
Object containing all of the properties pertaining to a player for your game - x, y, z, time, whatever you want to add to it.

options.onEntityUpdate(callback(state))

Event fired each time state is received for an entity.
callback function
Function to be invoked upon event firing.

state object literal
Object containing all of the properties pertaining to an entity for your game - x, y, z, time, whatever you want to add to it.

options.onPlayerRemove(callback(id))  
Event fired when a player has been removed from GarageServer.IO.