Question

My friend and I are porting our software to Mac OSX. The application is heavily built on SDL and we are having a hard time getting SDL linked and compiling in Qt5. We are not using any part of Qt in our code other then using the IDE for cross-platform ease.

Currently, I have SDL framework inside /Library/Frameworks/

Inside application.pro I have:

TEMPLATE = app
CONFIG += console
CONFIG -= app_bundle
CONFIG -= qt

SOURCES += main.cpp

macx {
   INCLUDEPATH += "/Library/Frameworks/SDL.framework/headers/"
}

In main.cpp I obviously have #include "SDL.h" and if I ctrl Click on the SDL.h it shows that it is linking to the framework…

When I go to build/compile I get this error:

14:21:24: Running steps for project BDGame...
14:21:24: Configuration unchanged, skipping qmake step.
14:21:24: Starting: "/usr/bin/make" -w
make: Entering directory `/Users/Kite/Dropbox/Wizardry Games/BDGame/BDGame-build-Desktop_Qt_5_0_0_clang_64bit_SDK-Release'
g++ -headerpad_max_install_names -mmacosx-version-min=10.6 -o BDGame main.o    
Undefined symbols for architecture x86_64:
  "_main", referenced from:
      start in crt1.10.6.o
     (maybe you meant: _SDL_main)
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
make: *** [BDGame] Error 1
make: Leaving directory `/Users/Kite/Dropbox/Wizardry Games/BDGame/BDGame-build-Desktop_Qt_5_0_0_clang_64bit_SDK-Release'
14:21:24: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project BDGame (kit: Desktop Qt 5.0.0 clang 64bit (SDK))
When executing step 'Make'

What am I doing incorrect that is stopping Qt from using SDL?

Answer 1

In your main.cpp file you have to declare int SDL_main(int, char**) function instead of main(). You also need to get SDLMain.h and SDLMain.m files distributed along with SDL bundle for OS X. These two are required to bootstrap your Cocoa application that will invoke further the SDL_main function.

I suppose you use Qt project (*.pro) file. You should have something like this in yours:

qtsdl.pro

QT       -= core gui

TARGET = qtsdl
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app

INCLUDEPATH += /Library/Frameworks/SDL.framework/Headers
LIBS += -framework Cocoa -framework SDL

SOURCES += \
    main.cpp

OBJECTIVE_SOURCES += \
    SDLMain.m

HEADERS += \
    SDLMain.h

main.cpp

#include <SDL.h>

int SDL_main(int argc, char *argv[])
{
    (void)argc;
    (void)argv;

    SDL_Surface *screen;

    if (SDL_Init(SDL_INIT_VIDEO) < 0)
        return 1;

    screen = SDL_SetVideoMode(640, 480, 32, SDL_OPENGL | SDL_HWSURFACE);
    if (!screen) {
        SDL_Quit();
        return 1;
    }

    SDL_Event event;
    bool running = true;

    while (running) {
        while (SDL_PollEvent(&event)) {
            switch (event.type) {
            case SDL_QUIT:
                running = false;
                break;
            case SDL_KEYDOWN:
                running = false;
                break;
            default:
                break;
            }
        }
    }

    SDL_Quit();
    return 0;
}

SDLMain.h and SDLMain.m take them from SDL framework distribution.