libSDL，CMake和

Question

我试图在我的mac上编译一个cmake项目，但它依赖于SDL框架。我安装了这个框架，在cmake向我报告之后，没有找到libSDL，我自己设置了以下导出变量(如cmake所建议的)：

export SDL_INCLUDE_DIR=/Library/Frameworks/SDL.framework/
export SDLIMAGE_LIBRARY=/Library/Frameworks/SDL_image.framework/
export SDLIMAGE_INCLUDE_DIR=/Library/Frameworks/SDL_image.framework/Headers

现在cmake完成了它，但是当我运行make时，我得到了以下消息：

Mats-MBP:build mats$ make
Linking CXX executable SDLExample
Undefined symbols for architecture i386:
 "_main", referenced from:
     start in crt1.10.6.o
    (maybe you meant: _SDL_main)
ld: symbol(s) not found for architecture i386
collect2: ld returned 1 exit status
make[2]: *** [src/SDLExample] Error 1
make[1]: *** [src/CMakeFiles/SDLExample.dir/all] Error 2
make: *** [all] Error 2

我为i386和x86_64都得到了这个。我忘了什么？

编辑：这些是文件内容：

Mats-MBP:build mats$ cat ../src/main.cpp 
/**
 * @file main.cpp
 *
 * A simple example-program to help you out with using SDL for 2D graphics.
 *
 * @author przemek
 */

#include <iostream>
#include <stdexcept>
#include <SDL.h>
#include <SDL_image.h>

using namespace std;

int main(int argc, char* argv[]) {
    try {
        // Try to initialize SDL (for video)
        if (SDL_Init(SDL_INIT_VIDEO) != 0) {
            throw runtime_error("Couldn't init SDL video!");
        }
        // Create a double-buffered screen surface:
        SDL_Surface* screen = SDL_SetVideoMode(800, 600, 24, SDL_DOUBLEBUF/* |     SDL_FULLSCREEN*/);
        if (!screen) {
            throw runtime_error("Couldn't set SDL video mode!");
        }

        // Use SDL_image library to load an image:
        SDL_Surface* image = IMG_Load("image.png");
//      SDL_Surface* image = IMG_Load("image.tga");
        if (!image) {
            throw runtime_error(SDL_GetError());
        }

        // "Pump" SDL events like keyboard presses and get the keystate:
        SDL_PumpEvents();
        Uint8* keyState = SDL_GetKeyState(0);

        // loop until user presses escape:
        while (!keyState[SDLK_ESCAPE]) {
            // Display a game background:
        SDL_Rect src, dst;          // Source and destination rectangles
        src.x = 0;
        src.y = 0;
        src.w = image->w;
        src.h = image->h;
        dst.x = 100;
        dst.y = 50;
        dst.w = image->w;
        dst.h = image->h;
        // Copy the image from 'image' to 'screen' surface
        SDL_BlitSurface(image, &src, SDL_GetVideoSurface(), &dst);

        // Flip surfaces (remember: double-buffering!) and clear the back buffer:
        SDL_Flip(screen);
        SDL_FillRect(screen, 0, 0);

        // Get new keyboard state:
        SDL_PumpEvents();
        keyState = SDL_GetKeyState(0);
    }

    // Free the screen surface & quit SDL
    SDL_FreeSurface(screen);
    SDL_Quit();
} catch (runtime_error& e) {
    cout << e.what() << endl;
    SDL_Quit();
}

return 0;
}

Answer 1

我通过删除.framework并将导出变量取消到这个框架来解决这个问题，并且我使用这个源代码来./configure、make、make。我删除了所有的cmake构建文件和cmake，并再次完成了我的项目，一切都解决了。

(要在on上编译SDL，您需要./configure --disable-assembly)

Answer 2

正如Ramon所说，许多平台都需要链接到SDLmain.lib。因此，在您的CMakeLists.txt文件中有这样的内容。

link_libraries (
   ${SDL_LIBRARY}
   ${SDLIMAGE_LIBRARY} # if using SDL_image, obviously
   SDLmain # Sadly not included in SDL_LIBRARY variable
)

下面是一个获取更多信息的简单页面：http://content.gpwiki.org/index.php/SDL:Tutorials:Setup