Minimal bgfx + SDL2

main.cpp

#include <SDL2/SDL.h>
#include <SDL2/SDL_syswm.h>
#include <bgfx/bgfx.h>
#include <bgfx/platform.h>
#include <bx/bx.h>
#include <bx/mutex.h>
#include <bx/thread.h>

void threadInit()
{
    bgfx::init();
    bgfx::reset(800, 600, BGFX_RESET_VSYNC);

    // Enable debug text.
    bgfx::setDebug(BGFX_DEBUG_TEXT /*| BGFX_DEBUG_STATS*/);

    // Set view 0 clear state.
    bgfx::setViewClear(0, BGFX_CLEAR_COLOR | BGFX_CLEAR_DEPTH, 0x303030ff, 1.0f, 0);
}

int counter = 0;

int threadMain(void* hoge)
{
    while (1) {
        bgfx::setViewRect(0, 0, 0, uint16_t(800), uint16_t(600));
        bgfx::touch(0);
        bgfx::dbgTextClear();
        bgfx::dbgTextPrintf(0, 1, 0x4f, "Counter:%d", counter++);
        bgfx::frame();
    }
}

inline bool sdlSetWindow(SDL_Window* _window)
{
    SDL_SysWMinfo wmi;
    SDL_VERSION(&wmi.version);
    if (!SDL_GetWindowWMInfo(_window, &wmi)) {
        return false;
    }

    bgfx::PlatformData pd;
#if BX_PLATFORM_LINUX || BX_PLATFORM_BSD
    pd.ndt = wmi.info.x11.display;
    pd.nwh = (void*)(uintptr_t)wmi.info.x11.window;
#elif BX_PLATFORM_OSX
    pd.ndt = NULL;
    pd.nwh = wmi.info.cocoa.window;
#elif BX_PLATFORM_WINDOWS
    pd.ndt = NULL;
    pd.nwh = wmi.info.win.window;
#elif BX_PLATFORM_STEAMLINK
    pd.ndt = wmi.info.vivante.display;
    pd.nwh = wmi.info.vivante.window;
#endif // BX_PLATFORM_
    pd.context = NULL;
    pd.backBuffer = NULL;
    pd.backBufferDS = NULL;
    bgfx::setPlatformData(pd);

    return true;
}

bx::Thread thread;

int main(void)
{
    SDL_Init(0);

    SDL_Window* window = SDL_CreateWindow("bgfx", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 800, 600, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);

    sdlSetWindow(window);
    bgfx::renderFrame();

    threadInit();
    bgfx::frame();
    thread.init(threadMain);

    bool exit = false;
    SDL_Event event;
    while (!exit) {
        bgfx::renderFrame();

        while (SDL_PollEvent(&event)) {

            switch (event.type) {
            case SDL_QUIT:
                exit = true;
                break;

            case SDL_WINDOWEVENT: {
                const SDL_WindowEvent& wev = event.window;
                switch (wev.event) {
                case SDL_WINDOWEVENT_RESIZED:
                case SDL_WINDOWEVENT_SIZE_CHANGED:
                    break;

                case SDL_WINDOWEVENT_CLOSE:
                    exit = true;
                    break;
                }
            } break;
            }
        }
    }

    bgfx::shutdown();

    while (bgfx::RenderFrame::NoContext != bgfx::renderFrame()) {
    };

    thread.shutdown();

    SDL_DestroyWindow(window);
    SDL_Quit();
}

https://gist.github.com/Coldragon/b2b22f1762db352baac94df7c0bee26e
Done it in C (it's the hello world and this one combined with little edit)

not work with latest bgfx version.

Running the sample with SDL2 (2.0.9)

> engine.exe!bx::debugBreak() Line 38 C++
engine.exe!bgfx::CallbackStub::fatal(const char * _filePath, unsigned short _line, bgfx::Fatal::Enum _code, const char * _str) Line 67 C++
engine.exe!bgfx::fatal(const char * _filePath, unsigned short _line, bgfx::Fatal::Enum _code, const char * _format, ...) Line 431 C++
engine.exe!bgfx::submit(unsigned short _id, bgfx::ProgramHandle _program, bgfx::OcclusionQueryHandle _occlusionQuery, unsigned int _depth, bool _preserveState) Line 4881 C++
engine.exe!bgfx::submit(unsigned short _id, bgfx::ProgramHandle _program, unsigned int _depth, bool _preserveState) Line 4876 C++
engine.exe!bgfx::touch(unsigned short _id) Line 4870 C++
engine.exe!threadMain(bx::Thread * __formal, void * __formal) Line 46 C++
engine.exe!bx::Thread::entry() Line 311 C++
engine.exe!bx::ThreadInternal::threadFunc(void * _arg) Line 81 C++

\source\external\bgfx.cmake-master\bgfx\src\bgfx.cpp (3393): BGFX Init complete.
\source\external\bgfx.cmake-master\bgfx\src\bgfx.cpp (1383): BGFX CHECK Must be called from render thread.
\source\external\bgfx.cmake-master\bgfx\src\bgfx.cpp (4881): BGFX CHECK Must be called from main thread.
engine.exe has triggered a breakpoint.