How do I cross-compile an SDL program that uses SDL_image?

SDL Development
1

I am on Ubuntu, trying to compile a C/SDL2 program to Windows using MinGW. I have included the development libraries and includes of both SDL2 and SDL_image like this:

CFLAGS =  -Wall -Werror -Wextra -pedantic
WLIBS = -lmingw32 \
-I ~/Downloads/SDL2-2.30.3/i686-w64-mingw32/include \
-L ~/Downloads/SDL2-2.30.3/i686-w64-mingw32/lib \
-I ~/Downloads/SDL2_image-2.6.0/i686-w64-mingw32/include \
-L ~/Downloads/SDL2_image-2.6.0/i686-w64-mingw32/lib \
-I ~/Downloads/mingw64/include \
-L ~/Downloads/mingw64/lib
build-w:
	i686-w64-mingw32-gcc ./src/files/* -o game.exe ${WLIBS} ${CFLAGS};

But I am running into an issue with the include files, I am getting this error:

In file included from ./src/files/game.c:3:
/home/gnxrly/Downloads/SDL2_image-2.6.0/i686-w64-mingw32/include/SDL2/SDL_image.h:32:10: fatal error: SDL.h: No such file or directory
   32 | #include "SDL.h"
      |          ^~~~~~~
compilation terminated.

I’m only linking -lSDL2, -lSDL2_image and -lpng for Linux, so those are the Windows equivalents. Do I also need to find the devel files for SDL1 for SDL_image to work?

2 
/*
  Linux:
  gcc main.c -o main -lSDL2

  Windows:
  Folgende Datei muss im Stamm-Ordner des Projektes sein libSDL2main.a
  x86_64-w64-mingw32-gcc main.c -o main.exe -lmingw32 -lSDL2main -lSDL2 -mwindows -I/usr/local/include -L/usr/local/bin -L.
*/

#include <SDL2/SDL.h>
#include <SDL2/SDL_main.h>

int main(int argc, char *argv[]) {
    SDL_Init(SDL_INIT_VIDEO);   
    SDL_Window *window = SDL_CreateWindow("An SDL2 window", 0, 0, 640, 480, SDL_WINDOW_OPENGL);
    SDL_Delay(3000);  
    SDL_DestroyWindow(window);
    SDL_Quit();
    return 0;
}

I have the following demo, which can be cross-compiled under Linux. These two paths still need to be adjusted -I/usr/local/include -L/usr/local/bin
And you also need to have the following lib: libSDL2main.a

3

I don’t understand. I don’t think anything is wrong with my program because it compiles and works flawlessly on Linux with gcc. The error is coming from the SDL_main.h file in the devel include that I downloaded for the cross-compilation.
I tried adding #include <SDL2/SDL_main.h> to all my files, as well as adding -lSDL2main -lSDL2 -mwindows to the flags, but the issue persists.
Also, where do I find libSDL2main.a and how do I link it?

4

According to the error message, what’s missing here is adding the SDL2 include dir itself to the search path, like -I ~/Downloads/SDL2-2.30.3/i686-w64-mingw32/include/SDL2

If linker errors turn up afte fixing this, they may be due to missing libSDL2main, which is part of the download so -lSDL2main should generally work, but see also [SDL2.x] WinMain vs. main - #5 by Daniel_Gibson for the correct order of linking SDL2 and SDL2main with MinGW

5

I read the forum you have linked and changed the order of the flags

WLIBS = -I ~/Downloads/SDL2-2.30.3/i686-w64-mingw32/include \
-L ~/Downloads/SDL2-2.30.3/i686-w64-mingw32/lib \
-I ~/Downloads/SDL2_image-2.6.0/i686-w64-mingw32/include \
-L ~/Downloads/SDL2_image-2.6.0/i686-w64-mingw32/lib \
-I ~/Downloads/mingw64/include \
-L ~/Downloads/mingw64/lib \
-lmingw32 -lSDL2main -lSDL2 -mwindows

I also swapped the C flags position so the libs can be at the end of the command

build-w:
	i686-w64-mingw32-gcc ./src/files/* -o game.exe ${CFLAGS} ${WLIBS};

I am still getting the same error.

6

you should’ve read my whole reply

According to the error message, what’s missing here is adding the SDL2 include dir itself to the search path, like -I ~/Downloads/SDL2-2.30.3/i686-w64-mingw32/include/SDL2

1 Like
7

My bad, I didn’t notice that.
This error is now gone, thanks a lot for your help!

8

Great, I hope it works now :slight_smile:

9

I hoped too, but there’s another problem

/usr/bin/i686-w64-mingw32-ld: /tmp/cc6JCKhW.o:init.c:(.text+0x5da): undefined reference to `IMG_Load'

I am getting this error for each time that I’m calling this function. I tried including the SDL2 directory inside the SDL2_image devel include folder like this

-I ~/Downloads/SDL2_image-2.6.0/i686-w64-mingw32/include/SDL2 \
-I ~/Downloads/SDL2_image-2.6.0/i686-w64-mingw32/include \

But it hasn’t worked

EDIT:
I just had to add the -lSDL2_image flag, and the error diappeared.

10

@Daniel_Gibson This insight useful for me :grinning: