Mencipta berbilang pemain yang selamat dan pantas dalam permainan di Unity dan NodeJS dengan contoh

pengenalan

Merancang pendekatan kepada pembangunan permainan berbilang pemain - memainkan salah satu peranan paling penting dalam pembangunan selanjutnya bagi keseluruhan projek, kerana ia termasuk banyak kriteria yang perlu kita ambil kira semasa mencipta produk yang benar-benar berkualiti tinggi. Dalam tutorial manifesto hari ini, kita akan melihat contoh pendekatan yang membolehkan kita mencipta permainan yang sangat pantas, sambil menghormati semua peraturan keselamatan dan anti-chit.

Jadi, mari kita tentukan kriteria utama untuk kita:

1. Permainan berbilang pemain memerlukan pendekatan khas untuk mengurus penyegerakan rangkaian, terutamanya apabila ia melibatkan masa nyata. protokol binari digunakan untuk mempercepatkan penyegerakan data antara pelanggan, dan medan reaktif akan membantu mengemas kini kedudukan pemain dengan kependaman yang minimum dan penjimatan memori.
2. Kuasa pelayan ialah prinsip penting di mana data kritikal hanya dikendalikan pada pelayan, memastikan integriti permainan dan perlindungan daripada penipu. Walau bagaimanapun, untuk kami memaksimumkan prestasi - pelayan hanya melakukan kemas kini kritikal dan kami menyerahkan selebihnya kepada pelanggan anti-penipuan.
3. Pelaksanaan anti-chit klien untuk memproses data yang kurang kritikal tanpa beban tambahan pada pelayan.

Komponen utama seni bina

1. Pihak pelanggan (Perpaduan): Pihak pelanggan bertanggungjawab untuk memaparkan keadaan permainan, menghantar tindakan pemain ke pelayan dan menerima kemas kini daripada pelayan. Medan reaktif juga digunakan di sini untuk mengemas kini kedudukan pemain secara dinamik.
2. Sisi pelayan (Node.js): Pelayan mengendalikan data kritikal (cth., pergerakan, perlanggaran dan tindakan pemain) dan menghantar kemas kini kepada semua pelanggan yang disambungkan. Data tidak kritikal boleh diproses pada klien dan dimajukan menggunakan pelayan kepada pelanggan lain.
3. Protokol Binari: Siri data binari digunakan untuk mengurangkan jumlah data yang dipindahkan dan meningkatkan prestasi.
4. Penyegerakan: Penyegerakan pantas data antara pelanggan disediakan untuk meminimumkan kependaman dan memastikan permainan yang lancar.
5. Anti Penipuan Pelanggan: Ia digunakan untuk jenis data yang boleh kami ubah pada klien dan hantar kepada pelanggan lain.

Langkah 1: Melaksanakan pelayan dalam Node.js

Pertama, anda perlu menyediakan pelayan pada Node.js. Pelayan akan bertanggungjawab untuk semua pengiraan kritikal dan memindahkan data yang dikemas kini kepada pemain.

Memasang persekitaran
Untuk mencipta pelayan pada Node.js, pasangkan kebergantungan yang diperlukan:

mkdir multiplayer-game-server
cd multiplayer-game-server
npm init -y
npm install socket.io

Socket.io memudahkan untuk melaksanakan komunikasi dua hala masa nyata antara pelanggan dan pelayan menggunakan soket web.

Pelaksanaan pelayan asas
Mari buat pelayan ringkas yang akan mengendalikan sambungan pelanggan, mendapatkan semula data, mengira keadaan kritikal dan menyegerakkannya antara semua pelanggan.

// Create a simple socket IO server
const io = require('socket.io')(3000, {
    cors: {
        origin: '*'
    }
});

// Simple example of game states
let gameState = {};
let playerSpeedConfig = {
    maxX: 1,
    maxY: 1,
    maxZ: 1
};

// Work with new connection
io.on('connection', (socket) => {
    console.log('Player connected:', socket.id);

    // Initialize player state for socket ID
    gameState[socket.id] = { x: 0, y: 0, z: 0 };

    // work with simple player command for movement
    socket.on('playerMove', (data) => {
        const { id, dx, dy, dz } = parsePlayerMove(data);

        // Check Maximal Values
        if(dx > playerSpeedConfig.maxX) dx = playerSpeedConfig.maxX;
        if(dy > playerSpeedConfig.maxY) dx = playerSpeedConfig.maxY;
        if(dz > playerSpeedConfig.maxZ) dx = playerSpeedConfig.maxZ;

        // update game state for current player
        gameState[id].x += dx;
        gameState[id].y += dy;
        gameState[id].z += dz;

        // Send new state for all clients
        const updatedData = serializeGameState(gameState);
        io.emit('gameStateUpdate', updatedData);
    });

    // Work with unsafe data
    socket.on('dataupdate', (data) => {
        const { id, unsafe } = parsePlayerUnsafe(data);

        // update game state for current player
        gameState[id].unsafeValue += unsafe;

        // Send new state for all clients
        const updatedData = serializeGameState(gameState);
        io.emit('gameStateUpdate', updatedData);
    });

    // Work with player disconnection
    socket.on('disconnect', () => {
        console.log('Player disconnected:', socket.id);
        delete gameState[socket.id];
    });
});

// Simple Parse our binary data
function parsePlayerMove(buffer) {
    const id = buffer.toString('utf8', 0, 16); // Player ID (16 bit)
    const dx = buffer.readFloatLE(16);         // Delta X
    const dy = buffer.readFloatLE(20);         // Delta  Y
    const dz = buffer.readFloatLE(24);         // Delta  Z
    return { id, dx, dy, dz };
}

// Simple Parse of unsafe data
function parsePlayerUnsafe(buffer) {
    const id = buffer.toString('utf8', 0, 16); // Player ID (16 bit)
    const unsafe = buffer.readFloatLE(16);     // Unsafe float
    return { id, unsafe };
}

// Simple game state serialization for binary protocol
function serializeGameState(gameState) {
    const buffers = [];
    for (const [id, data] of Object.entries(gameState)) {
        // Player ID
        const idBuffer = Buffer.from(id, 'utf8');

        // Position (critical) Buffer
        const posBuffer = Buffer.alloc(12);
        posBuffer.writeFloatLE(data.x, 0);
        posBuffer.writeFloatLE(data.y, 4);
        posBuffer.writeFloatLE(data.z, 8);

        // Unsafe Data Buffer
        const unsafeBuffer = Buffer.alloc(4);
        unsafeBuffer.writeFloatLE(data.unsafeValue, 0);

        // Join all buffers
        buffers.push(Buffer.concat([idBuffer, posBuffer, unsafeBuffer]));
    }
    return Buffer.concat(buffers);
}

Pelayan ini melakukan perkara berikut:

1. memproses sambungan pelanggan.
2. Menerima data pergerakan pemain dalam format binari, mengesahkannya, mengemas kini keadaan pada pelayan dan menghantarnya kepada semua pelanggan.
3. Menyegerakkan keadaan permainan dengan kependaman minimum, menggunakan format binari untuk mengurangkan jumlah data.
4. Majukan sahaja data tidak selamat yang datang daripada pelanggan.

Isi penting:

1. Kuasa pelayan: Semua data penting diproses dan disimpan pada pelayan. Pelanggan hanya menghantar arahan tindakan (cth., delta perubahan kedudukan).
2. Pemindahan data binari: Menggunakan protokol binari menjimatkan trafik dan meningkatkan prestasi rangkaian, terutamanya untuk pertukaran data masa nyata yang kerap.

Langkah 2: Melaksanakan bahagian klien pada Unity

Sekarang mari buat bahagian klien pada Unity yang akan berinteraksi dengan pelayan.

Untuk menyambungkan Unity ke pelayan di Socket.IO, anda perlu menyambungkan perpustakaan yang direka bentuk untuk Unity.
Dalam kes ini, kami tidak terikat kepada mana-mana pelaksanaan tertentu (malah semuanya serupa), tetapi hanya gunakan contoh abstrak.

Using reactive fields for synchronization
We will use reactive fields to update player positions. This will allow us to update states without having to check the data in each frame via the Update() method. Reactive fields automatically update the visual representation of objects in the game when the state of the data changes.

To get a reactive properties functional you can use UniRx.

Client code on Unity
Let's create a script that will connect to the server, send data and receive updates via reactive fields.

using UnityEngine;
using SocketIOClient;
using UniRx;
using System;
using System.Text;

// Basic Game Client Implementation
public class GameClient : MonoBehaviour
{
    // SocketIO Based Client
    private SocketIO client;

    // Our Player Reactive Position
    public ReactiveProperty<Vector3> playerPosition = new ReactiveProperty<Vector3>(Vector3.zero);

    // Client Initialization
    private void Start()
    {
        // Connect to our server
        client = new SocketIO("http://localhost:3000");

        // Add Client Events
        client.OnConnected += OnConnected;    // On Connected
        client.On("gameStateUpdate", OnGameStateUpdate); // On Game State Changed

        // Connect to Socket Async
        client.ConnectAsync();

        // Subscribe to our player position changed
        playerPosition.Subscribe(newPosition => {
            // Here you can interpolate your position instead
            // to get smooth movement at large ping
            transform.position = newPosition;
        });

        // Add Movement Commands
        Observable.EveryUpdate().Where(_ => Input.GetKey(KeyCode.W)).Subscribe(_ => ProcessInput(true));
        Observable.EveryUpdate().Where(_ => Input.GetKey(KeyCode.S)).Subscribe(_ => ProcessInput(false));
    }

    // On Player Connected
    private async void OnConnected(object sender, EventArgs e)
    {
        Debug.Log("Connected to server!");
    }

    // On Game State Update
    private void OnGameStateUpdate(SocketIOResponse response)
    {
        // Get our binary data
        byte[] data = response.GetValue<byte[]>();

        // Work with binary data
        int offset = 0;
        while (offset < data.Length)
        {
            // Get Player ID
            string playerId = Encoding.UTF8.GetString(data, offset, 16);
            offset += 16;

            // Get Player Position
            float x = BitConverter.ToSingle(data, offset);
            float y = BitConverter.ToSingle(data, offset + 4);
            float z = BitConverter.ToSingle(data, offset + 8);
            offset += 12;

            // Get Player unsafe variable
            float unsafeVariable = BitConverter.ToSingle(data, offset);

            // Check if it's our player position
            if (playerId == client.Id)
                playerPosition.Value = new Vector3(x, y, z);
            else
                UpdateOtherPlayerPosition(playerId, new Vector3(x, y, z), unsafeVariable);
        }
    }

    // Process player input
    private void ProcessInput(bool isForward){
        if (isForward)
            SendMoveData(new Vector3(0, 0, 1)); // Move Forward
        else
            SendMoveData(new Vector3(0, 0, -1)); // Move Backward
    }

    // Send Movement Data
    private async void SendMoveData(Vector3 delta)
    {
        byte[] data = new byte[28];
        Encoding.UTF8.GetBytes(client.Id).CopyTo(data, 0);
        BitConverter.GetBytes(delta.x).CopyTo(data, 16);
        BitConverter.GetBytes(delta.y).CopyTo(data, 20);
        BitConverter.GetBytes(delta.z).CopyTo(data, 24);

        await client.EmitAsync("playerMove", data);
    }

    // Send any unsafe data
    private async void SendUnsafeData(float unsafeData){
        byte[] data = new byte[20];
        Encoding.UTF8.GetBytes(client.Id).CopyTo(data, 0);
        BitConverter.GetBytes(unsafeData).CopyTo(data, 16);
        await client.EmitAsync("dataUpdate", data);
    }

    // Update Other players position
    private void UpdateOtherPlayerPosition(string playerId, Vector3 newPosition, float unsafeVariable)
    {
        // Here we can update other player positions and variables
    }

    // On Client Object Destroyed
    private void OnDestroy()
    {
        client.DisconnectAsync();
    }
}

Step 3: Optimize synchronization and performance

To ensure smooth gameplay and minimize latency during synchronization, it is recommended:

1. Use interpolation: Clients can use interpolation to smooth out movements between updates from the server. This compensates for small network delays.
2. Batch data sending: Instead of sending data on a per-move basis, use batch sending. For example, send updates every few milliseconds, which will reduce network load.
3. Reduce the frequency of updates: Reduce the frequency of sending data to a reasonable minimum. For example, updating 20-30 times per second may be sufficient for most games.

How to simplify working with the binary protocol?

In order to simplify your work with a binary protocol - create a basic principle of data processing, as well as schemes of interaction with it.

For our example, we can take a basic protocol where:
1) The first 4 bits are the maxa of the request the user is making (e.g. 0 - move player, 1 - shoot, etc.);
2) The next 16 bits are the ID of our client.
3) Next we fill in the data that is passed through the loop (some Net Variables), where we store the ID of the variable, the size of the offset in bytes to the beginning of the next variable, the type of the variable and its value.

For the convenience of version and data control - we can create a client-server communication schema in a convenient format (JSON / XML) and download it once from the server to further parse our binary data according to this schema for the required version of our API.

Client Anti-Cheat

It doesn't make sense to process every data on the server, some of them are easier to modify on the client side and just send to other clients.

To make you a bit more secure in this scheme - you can use client-side anti-chit system to prevent memory hacks - for example, my GameShield - a free open source solution.

Conclusion

We took a simple example of developing a multiplayer game on Unity with a Node.js server, where all critical data is handled on the server to ensure the integrity of the game. Using a binary protocol to transfer data helps optimize traffic, and reactive programming in Unity makes it easy to synchronize client state without having to use the Update() method.

This approach not only improves game performance, but also increases protection against cheating by ensuring that all key calculations are performed on the server rather than the client.

And of course, as always thank you for reading the article. If you still have any questions or need help in organizing your architecture for multiplayer project - I invite you to my Discord

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