将 SDL2 与 CMake 链接 [英] Linking SDL2 with CMake

问题描述

我在将 SDL2 链接到我的项目时遇到问题，这可能是因为我是 CMake 的新手，我不完全知道如何用它创建新项目.每次我尝试解决此问题的方法和方法都会导致以下问题之一:

I'm having problems linking SDL2 to my project, which probably are because I'm new to CMake, and I don't fully know how to create new projects with it. Every time and method I've tried to fix this problem has resulted in one of the following problems:

1. 无法定位 WinMain@16"
2. 多个未定义的引用错误
3. 未定义对 `SDL_main` 的引用

我尝试使用 find_package，直接链接到文件，链接到库文件，遵循教程(例如 https://trenki2.github.io/blog/2017/06/02/using-sdl2-with-cmake/)，寻找答案(他们中的大多数人都在谈论使用我无法开始工作的 find_package)(例如 将 SDL2 与 CMake 一起使用).

I have attempted to use find_package, linking directly to files, linking to library files, following tutorials (for example https://trenki2.github.io/blog/2017/06/02/using-sdl2-with-cmake/), searching for answers (most of them talk about using find_package which I can't get to work) (for example Using SDL2 with CMake).

SDL 2.0.12、CMake 3.17.0、7-Zip、mingw32-make、wget

SDL 2.0.12, CMake 3.17.0, 7-Zip, mingw32-make, wget

该项目应该是跨平台的，但主要的 devenv 是 Windows 10.所有脚本都从根文件夹vivaria"运行.

The project is supposed to be cross-platform, but the main devenv is Windows 10. All scripts are run from the root folder "vivaria".

vivaria/
├── build/
│   └── [cmake build files]
├── buildtools/
│   └── SDL2/SDL2-2.0.12/lib/x86 (and x64)
│                            ├── SDL2.lib
│                            └── SDL2main.libs
├── deploy/
├── resources/
├── scripts/
│   ├── build_windows_debug_x86.bat
│   └── install_buildtools_windows.bat
└── src/
    ├── CMakeLists.txt
    └── vivaria.cpp

build_windows_debug_x86.bat

cmake -G "MinGW Makefiles" -S .\src\ -B .\build\ -DCMAKE_BUILD_TYPE=Debug
cd .\build\
mingw32-make

vivaria.cpp

#include <iostream>
#include "SDL.h"

int main() {
    if (SDL_Init(SDL_INIT_VIDEO) != 0){
        std::cout << "Hello world" << std::endl;
        return 1;
    }
    
    SDL_Quit();
    return 0;
}

CMakeLists.txt:对 SDL_main 的未定义引用

cmake_minimum_required(VERSION 3.17)
project(Vivaria VERSION 1.0.0)

set(CMAKE_CXX_GLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -lmingw32")
# set(CMAKE_EXE_LINKER_FLAGS "-static-libgcc -static-libstdc++")

set(INCLUDE_DIR "${CMAKE_SOURCE_DIR}/../buildtools")
set(SDL2_DIR "${INCLUDE_DIR}/SDL2/SDL2-2.0.12")

set(SDL2_INCLUDE_DIRS "${SDL2_DIR}/include")
set(CMAKE_BINARY_DIR "${CMAKE_SOURCE_DIR}/../deploy")

# Support both 32 and 64 bit builds
if (${CMAKE_SIZEOF_VOID_P} MATCHES 8)
    set(SDL2_LIBRARIES "${SDL2_DIR}/lib/x64/SDL2main.lib;${SDL2_DIR}/lib/x64/SDL2.lib")
else ()
    set(SDL2_LIBRARIES "${SDL2_DIR}/lib/x86/SDL2main.lib;${SDL2_DIR}/lib/x86/SDL2.lib")
endif ()

# link dependencies
include_directories(${SDL2_INCLUDE_DIRS})
link_directories(${SDL2_LIBRARIES})

# Project files and linking
set(SOURCES vivaria.cpp)
add_executable(${PROJECT_NAME} vivaria.cpp)
target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})

控制台输出

F:\Koodit\Vivaria\build>mingw32-make
[ 50%] Linking CXX executable Vivaria.exe
c:/mingw/bin/../lib/gcc/mingw32/9.2.0/../../../../mingw32/bin/ld.exe: F:/Koodit/Vivaria/src/../buildtools/SDL2/SDL2-2.0.12/lib/x86/SDL2main.lib(Win32/Release/SDL_windows_main.obj):(.text[_main_getcmdline]+0xd1): undefined reference to `SDL_main'
collect2.exe: error: ld returned 1 exit status
CMakeFiles\Vivaria.dir\build.make:104: recipe for target 'Vivaria.exe' failed
mingw32-make[2]: *** [Vivaria.exe] Error 1
CMakeFiles\Makefile2:91: recipe for target 'CMakeFiles/Vivaria.dir/all' failed
mingw32-make[1]: *** [CMakeFiles/Vivaria.dir/all] Error 2
Makefile:99: recipe for target 'all' failed
mingw32-make: *** [all] Error 2

install_buildtools_windows.bat

set SDL2=SDL2-devel-2.0.12-VC.zip
set DOWNLOAD_DIR=%cd%\buildtools
set OUTPUT_DIR=%cd%\buildtools\SDL2

wget "https://libsdl.org/release/%SDL2%" -P "%DOWNLOAD_DIR%"

7z x "%DOWNLOAD_DIR%\%SDL2%" -y -o%OUTPUT_DIR%

del /F /Q %DOWNLOAD_DIR%\%SDL2%

正如你所看到的，我仍然有点"CMake 的新手，但我正在努力学习.

As you can see I'm still "a bit" new to CMake, but I'm trying to learn.

推荐答案

感谢 Tsyvarev！在源文件中设置宏 SDL_MAIN_HANDLED 解决了这个问题.

Thanks to Tsyvarev! Setting the macro SDL_MAIN_HANDLED in the source file fixed the problem.

#define SDL_MAIN_HANDLED // insert this
#include <iostream>
#include "SDL.h"

int main() {
    if (SDL_Init(SDL_INIT_VIDEO) != 0){
        std::cout << "Hello world" << std::endl;
        return 1;
    }
    
        std::cout << "Hello world 2" << std::endl;

    SDL_Quit();
    return 0;
}

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