Unity Netcode Patterns

Distributed Authority Setup

NetworkManager Configuration

• Use Distributed Authority topology
• Configure player prefab spawning
• Set up scene management for network

NetworkBehaviour Basics

csharp
1public class GridManager : NetworkBehaviour
2{
3    public override void OnNetworkSpawn()
4    {
5        if (IsServer)
6        {
7            // Initialize on Session Owner
8            InitializeGrid();
9        }
10    }
11    
12    public override void OnNetworkDespawn()
13    {
14        // Cleanup
15    }
16}

NetworkVariable Patterns

Simple Value Sync

csharp
1private NetworkVariable<int> health = new NetworkVariable<int>(
2    default,
3    NetworkVariableReadPermission.Everyone,
4    NetworkVariableWritePermission.Server
5);
6
7// Update on server
8if (IsServer)
9{
10    health.Value = newHealth;
11}
12
13// Read on all clients
14void Update()
15{
16    if (health.Value != _lastHealth)
17    {
18        UpdateHealthUI(health.Value);
19        _lastHealth = health.Value;
20    }
21}

Struct Sync

csharp
1public struct PlayerStats : INetworkSerializable
2{
3    public int Health;
4    public int Mana;
5    
6    public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
7    {
8        serializer.SerializeValue(ref Health);
9        serializer.SerializeValue(ref Mana);
10    }
11}
12
13private NetworkVariable<PlayerStats> stats = new NetworkVariable<PlayerStats>();

NetworkList Patterns

Collection Sync

csharp
1private NetworkList<TileData> _tileGrid;
2
3public override void OnNetworkSpawn()
4{
5    _tileGrid = new NetworkList<TileData>();
6    
7    if (IsServer)
8    {
9        InitializeGrid();
10    }
11    
12    _tileGrid.OnListChanged += HandleTileGridChanged;
13}
14
15private void HandleTileGridChanged(NetworkListEvent<TileData> changeEvent)
16{
17    switch (changeEvent.Type)
18    {
19        case NetworkListEvent<TileData>.EventType.Add:
20            // New tile added
21            break;
22        case NetworkListEvent<TileData>.EventType.Remove:
23            // Tile removed
24            break;
25        case NetworkListEvent<TileData>.EventType.Value:
26            // Tile value changed
27            break;
28    }
29}

RPC Patterns

ServerRpc - Client to Server

csharp
1[ServerRpc(RequireOwnership = false)]
2public void ClaimTileServerRpc(int x, int y, ServerRpcParams rpcParams = default)
3{
4    if (!IsServer) return;
5    
6    ulong clientId = rpcParams.Receive.SenderClientId;
7    
8    // Validate and process
9    if (ValidateTileClaim(x, y, clientId))
10    {
11        ClaimTile(x, y, clientId);
12    }
13}

ClientRpc - Server to Clients

csharp
1[ClientRpc]
2public void TileDestroyedClientRpc(int x, int y)
3{
4    // Execute on all clients
5    SpawnDestructionParticles(x, y);
6    PlayDestructionSound();
7}

Targeted ClientRpc

csharp
1[ClientRpc]
2public void ShowVictoryClientRpc(ClientRpcParams rpcParams = default)
3{
4    // Only show to specific client
5    UIManager.Instance.ShowVictoryScreen();
6}

Ownership Patterns

Client Owns Character

csharp
1public class PlayerController : NetworkBehaviour
2{
3    void Update()
4    {
5        if (!IsOwner) return; // Only owner processes input
6        
7        HandleInput();
8    }
9    
10    [ServerRpc]
11    void MoveServerRpc(Vector3 position)
12    {
13        // Server validates movement
14        transform.position = position;
15    }
16}

Server Owns Grid

csharp
1public class GridManager : NetworkBehaviour
2{
3    void Update()
4    {
5        if (!IsServer) return; // Only server modifies grid
6        
7        ProcessGridUpdates();
8    }
9}

Late Join Handling

Sending State to Late Joiners

csharp
1public override void OnNetworkSpawn()
2{
3    if (IsServer)
4    {
5        // Late joiner - send current state
6        if (NetworkManager.Singleton.ConnectedClients.Count > 1)
7        {
8            SendFullGridStateClientRpc();
9        }
10    }
11}
12
13[ClientRpc]
14void SendFullGridStateClientRpc()
15{
16    // Receive full grid state
17    InitializeGridFromState();
18}

Network Events

Connection Events

csharp
1public override void OnNetworkSpawn()
2{
3    if (IsServer)
4    {
5        NetworkManager.Singleton.OnClientConnectedCallback += OnClientConnected;
6        NetworkManager.Singleton.OnClientDisconnectCallback += OnClientDisconnected;
7    }
8}
9
10void OnClientConnected(ulong clientId)
11{
12    Debug.Log($"[SessionManager] Client {clientId} connected");
13    // Send current game state
14}
15
16void OnClientDisconnected(ulong clientId)
17{
18    Debug.Log($"[SessionManager] Client {clientId} disconnected");
19    // Clean up client-specific data
20}

Common Solutions

Synchronized Timers

csharp
1private NetworkVariable<float> turnTimer = new NetworkVariable<float>();
2
3void Update()
4{
5    if (IsServer)
6    {
7        turnTimer.Value -= Time.deltaTime;
8        if (turnTimer.Value <= 0)
9        {
10            EndTurn();
11        }
12    }
13}

Authority Validation

csharp
1[ServerRpc(RequireOwnership = false)]
2public void PlayCardServerRpc(int cardId, ServerRpcParams rpcParams = default)
3{
4    if (!IsServer) return;
5    
6    ulong clientId = rpcParams.Receive.SenderClientId;
7    
8    // Validate player can play this card
9    if (!CanPlayerPlayCard(clientId, cardId))
10    {
11        Debug.LogWarning($"[CardManager] Invalid card play from {clientId}");
12        return;
13    }
14    
15    // Execute card
16    ExecuteCard(cardId, clientId);
17}

Performance Tips

Minimize Network Updates

• Update NetworkVariables only when values change
• Batch NetworkList updates when possible
• Use ClientRpc for one-time events, NetworkVariable for frequent updates

Optimize Message Size

• Keep RPC parameters small
• Use enums instead of strings when possible
• Compress data structures when needed