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To join a multiplayer game, a player must connect to an existing server using the SetupClient() function. This establishes a connection to the host and allows both players to begin the match.

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How joining works

1

Create the client host

First, create a client-side ENet host:
main.cpp
clientHost = enet_host_create(
    NULL,  // create a client host
    1,     // only 1 outgoing connection
    2,     // allow up to 2 channels
    0,     // unlimited download bandwidth
    0      // unlimited upload bandwidth
);
Passing NULL as the first parameter creates a client host that can initiate connections but not accept them.
2

Verify client creation

Check if the client host was created successfully:
main.cpp
if (clientHost == NULL){
    printf("failed to create client host\n");
    return false;
}
If creation fails, the game returns to the main menu.
3

Configure server address

Set up the address of the server to connect to:
main.cpp
ENetAddress address;
enet_address_set_host(&address, SERVER_IP);
address.port = SERVER_PORT;
The enet_address_set_host() function resolves the hostname or IP address (by default “127.0.0.1”) to an ENet address.
4

Connect to the server

Initiate the connection to the server:
main.cpp
serverPeer = enet_host_connect(clientHost,
    &address,  
    2,  // number of channels
    0   // user data
);
if (serverPeer == NULL){
    printf("failed to connect to server");
    return false;
}
printf("Connecting to %s:%d...\n",SERVER_IP,SERVER_PORT);
return true;
This returns a peer object representing the connection to the server.
5

Wait for connection confirmation

The game enters the JOINING state and waits for the connection to be established:
main.cpp
ENetEvent event;
while (enet_host_service(clientHost, &event, 0) > 0) {
    if (event.type == ENET_EVENT_TYPE_CONNECT) {
        printf("Connected to server!\n");
        connectionState = "CONNECTED";
        
        // Start the game
        state = "MULTIPLAYER";
    }
}
Once the connection is confirmed, the game transitions to the multiplayer gameplay state.

​
Complete SetupClient function

main.cpp
bool SetupClient() {
    // create a client host
    clientHost = enet_host_create(
        NULL,
        1,
        2,
        0,
        0
    );
    if (clientHost == NULL){
        printf("failed to create client host\n");
        return false;
    }

    ENetAddress address;
    enet_address_set_host(&address, SERVER_IP);
    address.port = SERVER_PORT;

    serverPeer = enet_host_connect(clientHost,
        &address,  
        2,
        0
    );
    if (serverPeer == NULL){
        printf("failed to connect to server");
        return false;
    }
    printf("Connecting to %s:%d...\n",SERVER_IP,SERVER_PORT);
    return true;
}

​
Network variables

The following global variables manage the client connection:
main.cpp
ENetHost* clientHost = nullptr;
ENetPeer* serverPeer = nullptr; // for client connection to server
When joining, the client uses clientHost to manage its networking and stores the server connection in serverPeer.

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Connection to localhost vs LAN

By default, the game connects to 127.0.0.1 (localhost), which only works if both players are on the same machine. For LAN play, modify the SERVER_IP constant to the host’s local network IP address:
main.cpp
const char* SERVER_IP = "192.168.1.100"; // Replace with host's IP
Ensure both players are on the same network and the host’s firewall allows incoming connections on port 7777.

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Troubleshooting

If connection fails:
  • Verify the server is running and in the HOSTING state
  • Check that SERVER_IP points to the correct host address
  • Ensure port 7777 is not blocked by firewall rules
  • Confirm ENet has been initialized before calling SetupClient()

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