How to build WebAssembly program with SDL_image 3.0?

I have created a simple C++ program

/* checkers.cpp */ #define SDL_MAIN_USE_CALLBACKS 1 // NOLINT // #include <SDL3/SDL.h> //uncomment for release #include <SDL3/SDL_error.h> //clang-tidy #include <SDL3/SDL_events.h> //clang-tidy #include <SDL3/SDL_init.h> //clang-tidy #include <SDL3/SDL_log.h> //clang-tidy #include <SDL3/SDL_main.h> //keep uncommented for release #include <SDL3/SDL_render.h> //clang-tidy #include <SDL3/SDL_stdinc.h> //clang-tidy #include <SDL3/SDL_video.h> //clang-tidy #include <SDL3_image/SDL_image.h> //clang-tidy const int static WIDTH = 800; const int static HEIGHT = 800; const int static MAX = 255; const float static SCALE = 4.0F; static char message[30] = "Hello World!"; // NOLINT /* This function runs once at startup. */ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) { // NOLINT SDL_Window *window = nullptr; SDL_Renderer *renderer = nullptr; /* Create the window */ if (!SDL_CreateWindowAndRenderer("Hello World", WIDTH, HEIGHT, SDL_WINDOW_FULLSCREEN, &window, &renderer)) { SDL_Log("Couldn't create window and renderer: %s", // NOLINT SDL_GetError()); // NOLINT return SDL_APP_FAILURE; } *appstate = renderer; const SDL_Texture *texture = IMG_LoadTexture(renderer, "blender/blue.ortho.png"); const int printf_rc = SDL_snprintf(message, sizeof(message), "SDL_Texture.w %d", texture->w); if (printf_rc < 0) { SDL_Log("SDL_snprintf return code: %d", printf_rc); // NOLINT } return SDL_APP_CONTINUE; } /* This function runs when a new event (mouse input, keypresses, etc) occurs. */ SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) { // NOLINT if (event->type == SDL_EVENT_KEY_DOWN || event->type == SDL_EVENT_QUIT) { return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ } return SDL_APP_CONTINUE; } /* This function runs once per frame, and is the heart of the program. */ SDL_AppResult SDL_AppIterate(void *appstate) { // NOLINT auto *renderer = static_cast<SDL_Renderer *>(appstate); int width = 0; int height = 0; /* Center the message and scale it up */ SDL_GetRenderOutputSize(renderer, &width, &height); SDL_SetRenderScale(renderer, SCALE, SCALE); const float xpos = ((static_cast<float>(width) / SCALE) - (static_cast<float>(SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE) * sizeof(message))) / 2; const float ypos = ((static_cast<float>(height) / SCALE) - SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE) / 2; /* Draw the message */ SDL_SetRenderDrawColor(renderer, 0, 0, 0, MAX); SDL_RenderClear(renderer); SDL_SetRenderDrawColor(renderer, MAX, MAX, MAX, MAX); SDL_RenderDebugText(renderer, xpos, ypos, message); SDL_RenderPresent(renderer); return SDL_APP_CONTINUE; } /* This function runs once at shutdown. */ void SDL_AppQuit(void *appstate, SDL_AppResult result) { } // NOLINT misc-use-anonymous-namespace

which uses the IMG_LoadTexture function from SDL_image 3.0 I can successfully compile and execute it with with clang 22.1.1 and Windows 11 SDK using -

clang -o checkers.exe checkers.cpp -ISDL3-3.4.2\include -ISDL3_image-3.4.0\include -lSDL3-3.4.2\lib\x64\SDL3 -lSDL3_image-3.4.0\lib\x64\SDL3_image -Wl,/subsystem:console

However, when I try to compile it to WebAssembly with -

emcc checkers.cpp -ISDL3-3.4.2\include -ISDL3_image-3.4.0\include -sUSE_SDL=3 -sUSE_SDL_IMAGE=3

it fails with -

wasm-ld: error: C:\Users\xxxx\AppData\Local\Temp\emscripten_temp_a5fwe36t\checkers.o: undefined symbol: IMG_LoadTexture

Next, I installed MSYS2 and followed this recipe and ran

emcmake cmake -S . -B build -G "Unix Makefiles"

but it failed with -

CMake Error at build/CMakeFiles/4.2.3/CMakeSystem.cmake:6 (include): include could not find requested file:/home/xxx/SDL3/C:/Users/xxx/dev/msys64/ucrt64/lib/emscripten/cmake/Modules/Platform/Emscripten.cmake CMake Error: CMAKE_C_COMPILER not set, after EnableLanguage

so I edited build/CMakeFiles/4.2.3/CMakeSystem.cmake and corrected the path to

include("/ucrt64/lib/emscripten/cmake/Modules/Platform/Emscripten.cmake")

and added the following to CMakeCache.txt -

//CMAKE_C_COMPILER CMAKE_C_COMPILER:UNINITIALIZED=/ucrt64/lib/emscripten/emcc //CMAKE_CXX_COMPILER CMAKE_CXX_COMPILER:UNINITIALIZED= /ucrt64/lib/emscripten/em++

this time

emcmake cmake -S . -B build -G "Unix Makefiles"

ran without errors but

cd build emmake make

failed with

emmake: "make" in "C:/Users/xxxx/dev/msys64/home/xxxx/SDL3/build" [ 0%] Building C object vendored/SDL/CMakeFiles/SDL3-static.dir/cmake_pch.h.pch In file included from <built-in>:1: C:/Users/xxxx/dev/msys64/home/xxxx/SDL3/build/vendored/SDL/CMakeFiles/SDL3-static.dir/cmake_pch.h:4:10: fatal error: '/home/xxxx/SDL3/vendored/SDL/src/SDL_internal.h' file not found 4 | #include "/home/xxxx/SDL3/vendored/SDL/src/SDL_internal.h" | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1 error generated.

vendored/SDL is the location of SDL

Any ideas?