Step 1: Create Project Directory Шаг 1: Создание директории проекта

Create a workspace folder and a new project directory for your server project: Создайте рабочую папку и новую директорию проекта для вашего сервера:

Windows (Command Prompt / PowerShell)

mkdir C:\projects\sdl3-net-server-test
cd C:\projects\sdl3-net-server-test

Ubuntu (Terminal)

mkdir -p ~/projects/sdl3-net-server-test
cd ~/projects/sdl3-net-server-test

Step 2: Create Source Files (main.cpp & CMakeLists.txt) Шаг 2: Создание исходных файлов (main.cpp и CMakeLists.txt)

You can create these files using Notepad / Sublime Text on Windows, or nano in Ubuntu terminal: Вы можете создать эти файлы через Блокнот / Sublime Text в Windows или с помощью nano в терминале Ubuntu:

Windows (Terminal / Notepad)

notepad main.cpp
notepad CMakeLists.txt

Ubuntu (Terminal / Nano)

nano main.cpp
nano CMakeLists.txt

1A. File Contents for main.cpp (Classic Loop) 1A. Содержимое файла main.cpp (Классический цикл)

#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
#include <SDL3_net/SDL_net.h>
#include <vector>

int main(int argc, char* argv[]) {
    if (!SDL_Init(0)) {
        SDL_Log("SDL Initialization failed: %s", SDL_GetError());
        return -1;
    }

    if (!NET_Init()) {
        SDL_Log("NET_Init failed: %s", SDL_GetError());
        SDL_Quit();
        return -1;
    }

    const Uint16 port = 12345;
    NET_Server* server = NET_CreateServer(NULL, port, 0);
    if (!server) {
        SDL_Log("Failed to create server on port %u: %s", port, SDL_GetError());
        NET_Quit();
        SDL_Quit();
        return -1;
    }

    SDL_Log("SDL3_net Server listening on port %u...", port);

    std::vector<NET_StreamSocket*> clients;
    bool running = true;

    while (running) {
        NET_StreamSocket* new_client = nullptr;
        if (NET_AcceptClient(server, &new_client) && new_client) {
            SDL_Log("New client connected!");
            clients.push_back(new_client);

            const char* message = "Hello from SDL3_net Server!\n";
            NET_WriteToStreamSocket(new_client, message, (int)SDL_strlen(message));
        }

        char buffer[512];
        for (auto it = clients.begin(); it != clients.end();) {
            NET_StreamSocket* client = *it;
            bool client_active = true;

            while (true) {
                int bytes_read = NET_ReadFromStreamSocket(client, buffer, sizeof(buffer) - 1);

                if (bytes_read > 0) {
                    buffer[bytes_read] = '\0';
                    SDL_Log("Received message: %s", buffer);
                } else if (bytes_read == 0) {
                    break; // No more data available
                } else {
                    SDL_Log("Client disconnected or socket error.");
                    NET_DestroyStreamSocket(client);
                    it = clients.erase(it);
                    client_active = false;
                    break;
                }
            }

            if (client_active) {
                ++it;
            }
        }

        SDL_Delay(10);
    }

    for (auto* client : clients) {
        NET_DestroyStreamSocket(client);
    }
    clients.clear();

    NET_DestroyServer(server);
    NET_Quit();
    SDL_Quit();

    return 0;
}

1B. File Contents for main.cpp (SDL3 Callbacks API) 1B. Содержимое файла main.cpp (SDL3 Callbacks API)

#define SDL_MAIN_USE_CALLBACKS 1
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
#include <SDL3_net/SDL_net.h>
#include <vector>

struct AppState {
    NET_Server* server = nullptr;
    std::vector<NET_StreamSocket*> clients;
};

SDL_AppResult SDL_AppInit(void** appstate, int argc, char* argv[]) {
    if (!SDL_Init(0)) {
        SDL_Log("SDL Initialization failed: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }

    if (!NET_Init()) {
        SDL_Log("NET_Init failed: %s", SDL_GetError());
        return SDL_APP_FAILURE;
    }

    AppState* state = new AppState();
    *appstate = state;

    const Uint16 port = 12345;
    state->server = NET_CreateServer(NULL, port, 0);
    if (!state->server) {
        SDL_Log("Failed to create server on port %u: %s", port, SDL_GetError());
        return SDL_APP_FAILURE;
    }

    SDL_Log("SDL3_net Server listening on port %u (Callbacks API)...", port);
    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppEvent(void* appstate, SDL_Event* event) {
    if (event->type == SDL_EVENT_QUIT) {
        return SDL_APP_SUCCESS;
    }
    return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppIterate(void* appstate) {
    auto* state = static_cast<AppState*>(appstate);

    NET_StreamSocket* new_client = nullptr;
    if (NET_AcceptClient(state->server, &new_client) && new_client) {
        SDL_Log("New client connected!");
        state->clients.push_back(new_client);

        const char* message = "Hello from SDL3_net Server!\n";
        NET_WriteToStreamSocket(new_client, message, (int)SDL_strlen(message));
    }

    char buffer[512];
    for (auto it = state->clients.begin(); it != state->clients.end();) {
        NET_StreamSocket* client = *it;
        bool client_active = true;

        while (true) {
            int bytes_read = NET_ReadFromStreamSocket(client, buffer, sizeof(buffer) - 1);

            if (bytes_read > 0) {
                buffer[bytes_read] = '\0';
                SDL_Log("Received message: %s", buffer);
            } else if (bytes_read == 0) {
                break; // No more data available
            } else {
                SDL_Log("Client disconnected or socket error.");
                NET_DestroyStreamSocket(client);
                it = state->clients.erase(it);
                client_active = false;
                break;
            }
        }

        if (client_active) {
            ++it;
        }
    }

    SDL_Delay(10);
    return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void* appstate, SDL_AppResult result) {
    if (appstate) {
        auto* state = static_cast<AppState*>(appstate);

        for (auto* client : state->clients) {
            NET_DestroyStreamSocket(client);
        }
        state->clients.clear();

        if (state->server) {
            NET_DestroyServer(state->server);
        }
        delete state;
    }
    NET_Quit();
    SDL_Quit();
}

2. File Contents for CMakeLists.txt 2. Содержимое файла CMakeLists.txt

cmake_minimum_required(VERSION 3.21)

# Default to Debug if CMAKE_BUILD_TYPE is not set via command line
if(NOT CMAKE_BUILD_TYPE)
    set(CMAKE_BUILD_TYPE "Debug")
endif()

project(sdl3_net_server_test CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# -----------------------------------------------------------------------------
# Locate SDL3 and SDL3_net Packages via Custom Paths
# -----------------------------------------------------------------------------
if(WIN32)
    set(SDL3_DIR "C:/libs/sdl3-3.4.16-mingw/lib/cmake/SDL3")
    set(SDL3_net_DIR "C:/libs/sdl3-net-3.2.0-mingw/lib/cmake/SDL3_net")
else()
    set(SDL3_DIR "$ENV{HOME}/libs/sdl3-3.4.16-ubuntu/lib/cmake/SDL3")
    set(SDL3_net_DIR "$ENV{HOME}/libs/sdl3-net-3.2.0-ubuntu/lib/cmake/SDL3_net")
endif()

find_package(SDL3 REQUIRED CONFIG)
find_package(SDL3_net REQUIRED CONFIG)

# -----------------------------------------------------------------------------
# Target Definition
# -----------------------------------------------------------------------------
set(PROJECT_SOURCES
    main.cpp
)

add_executable(app ${PROJECT_SOURCES})

# Link SDL3 and SDL3_net statically (automatically brings in include dirs and
# socket system libraries like ws2_32 / iphlpapi on Windows)
target_link_libraries(app PRIVATE SDL3::SDL3-static SDL3_net::SDL3_net-static)

# -----------------------------------------------------------------------------
# Platform-Specific Compiler & Linker Flags
# -----------------------------------------------------------------------------
if(WIN32)
    target_compile_options(app PRIVATE -Os)
    target_link_options(app PRIVATE -static -s -static-libgcc -mconsole)
endif()

Step 3: Create Build & Execution Scripts Шаг 3: Создание скриптов сборки и запуска

Windows (MinGW / Batch Scripts)

config-exe.bat

cmake -G Ninja -S . -B dist/win

build-exe.bat

cmake --build dist/win

run-exe.bat

@echo off
.\dist\win\app.exe

Run the scripts sequentially in Command Prompt or PowerShell: Последовательно запустите скрипты в командной строке или PowerShell:

config-exe.bat
build-exe.bat
run-exe.bat

Ubuntu (Bash Scripts)

config-bin.sh

#!/usr/bin/env bash
set -e
cmake -G Ninja -S . -B dist/linux

build-bin.sh

#!/usr/bin/env bash
set -e
cmake --build dist/linux

run-bin.sh

#!/usr/bin/env bash
set -e
./dist/linux/app

Grant execute permissions on Ubuntu before running: Предоставьте права на выполнение в Ubuntu перед запуском:

chmod +x config-bin.sh build-bin.sh run-bin.sh
./config-bin.sh
./build-bin.sh
./run-bin.sh

Step 4: Expected Output Шаг 4: Ожидаемый результат

Upon running the server, the console will print a message indicating it is waiting for client connections: После запуска сервера в консоли появится сообщение о том, что он ожидает подключения клиентов:

INFO: SDL3_net Server listening on port 12345...

or (if using the Callbacks API version): или (если используется версия с Callbacks API):

SDL3_net Server listening on port 12345 (Callbacks API)...