CMake not linking SDL library? [duplicate] - c++

Question

I'm looking for the simplest way to compile a c++ program using SDL2 and SDL_image with cmake.
Here is my best attempt, after hours of searching:
CMakeLists.txt
project(shooter-cmake2)
cmake_minimum_required(VERSION 2.8)
set(SOURCES
shooter.cpp
classes.cpp
utils.cpp
)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
add_executable(${PROJECT_NAME} ${SOURCES})
INCLUDE(FindPkgConfig)
PKG_SEARCH_MODULE(SDL2 REQUIRED sdl2)
PKG_SEARCH_MODULE(SDL2_image REQUIRED sdl2_image)
INCLUDE_DIRECTORIES(${SDL2_INCLUDE_DIRS} ${SDL2IMAGE_INCLUDE_DIR})
TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${SDL2_LIBRARIES} ${SDL2IMAGE_LIBRARY})
I get these errors:
In function `loadTexture(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, SDL_Renderer*)':
undefined reference to `IMG_LoadTexture'
collect2: ld returned 1 exit status
Here is the function call:
#include "SDL.h"
#include "SDL_image.h"
SDL_Texture* loadTexture(const std::string &file, SDL_Renderer *ren){
SDL_Texture *texture = IMG_LoadTexture(ren, file.c_str());
texture != nullptr or die("LoadTexture");
return texture;
}

Answer 1

I think that the following will work, as it finds the libraries on my ubuntu system and the example function you provided can link:
project(shooter-cmake2)
cmake_minimum_required(VERSION 2.8)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
add_executable(${PROJECT_NAME} src/test.cpp)
INCLUDE(FindPkgConfig)
PKG_SEARCH_MODULE(SDL2 REQUIRED sdl2)
PKG_SEARCH_MODULE(SDL2IMAGE REQUIRED SDL2_image>=2.0.0)
INCLUDE_DIRECTORIES(${SDL2_INCLUDE_DIRS} ${SDL2IMAGE_INCLUDE_DIRS})
TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${SDL2_LIBRARIES} ${SDL2IMAGE_LIBRARIES})
If cmake is executed with --debug-output it outputs:
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.26")
Called from: [2] /usr/share/cmake-2.8/Modules/FindPkgConfig.cmake
[1] $USER/stack-overflow/cmake-sdl2-image/CMakeLists.txt
-- checking for one of the modules 'sdl2'
Called from: [1] $USER/stack-overflow/cmake-sdl2-image/CMakeLists.txt
-- checking for one of the modules 'SDL2_image>=2.0.0'
Called from: [1] $USER/stack-overflow/cmake-sdl2-image/CMakeLists.txt
This made me check the contents of
/usr/lib/x86_64-linux-gnu/pkgconfig/sdl2.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/SDL2_image.pc
I noticed that SDL2_image.pc contains
Name: SDL2_image
which I assumed should match the third parameter to PKG_SEARCH_MODULE for this library.

Answer 2

There are two blog posts about this here:
Using SDL2 with CMake
Using SDL2_image with CMake
Basically you need a FindSDL2.cmake and FindSDL2_image.cmake module. They can be based of the ones that work for SDL 1.2 which are included in CMake already. Using these Find modules will also work on Windows.
If you are on Linux and only need SDL2 you don't even need the FindSDL2.cmake as the following already works:
cmake_minimum_required(VERSION 3.7)
project(SDL2Test)
find_package(SDL2 REQUIRED)
include_directories(${SDL2_INCLUDE_DIRS})
add_executable(SDL2Test Main.cpp)
target_link_libraries(SDL2Test ${SDL2_LIBRARIES})

Answer 3

I was having trouble with these answers, I think cmake changed the way to import targets. Following #trenki blog post I needed to change my CMakeLists.txt to:
project(SDL2Test)
find_package(SDL2 REQUIRED COMPONENTS SDL2::SDL2)
add_executable(SDL2Test main.cpp)
target_link_libraries(SDL2Test SDL2::SDL2)
Currently this works out of the box on Arch Linux.

Answer 4

I introduced a modern and portable approach for linking to the SDL2, SDL2_image. These SDL2 CMake modules let you build an SDL2 & SDL2_image project as follows :
list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/sdl2)
find_package(SDL2 REQUIRED)
find_package(SDL2_image REQUIRED)
target_link_libraries(${PROJECT_NAME} SDL2::Main SDL2::Image)
You should just clone the repo in your project:
git clone https://github.com/aminosbh/sdl2-cmake-modules cmake/sdl2
Note: If CMake didn't find the SDL2/SDL2_image libraries (in Windows), we can specify the CMake options SDL2_PATH and SDL2_IMAGE_PATH as follows:
cmake .. -DSDL2_PATH="/path/to/sdl2" -DSDL2_IMAGE_PATH="/path/to/sdl2-image"
It supports also other related libraries : SDL2_ttf, SDL2_net, SDL2_mixer and SDL2_gfx. For more details, please read the README.md file.
You can find a list of examples/samples and projects that uses these modules here : https://github.com/aminosbh/sdl-samples-and-projects

Answer 5

Since 2.6 version, SDL2_image installation is shipped with CMake config script SDL2_imageConfig.cmake/SDL2_image-config.cmake.
So find_package(SDL2_image) works without any additional FindSDL2_image.cmake module, and creates IMPORTED target SDL2_image::SDL2_image:
find_package(SDL2_image REQUIRED)
target_link_libraries(<executable-target> SDL2_image::SDL2_image)
Note, that variables like SDL2_IMAGE_LIBRARIES or SDL2_IMAGE_INCLUDE_DIRS are NOT set in this case, so using them is meaningless.

Answer 6

The following commands works fine for me:
set(SDL_INCLUDE_DIR "/usr/include/SDL2")
set(SDL_LIBRARY "SDL2")
include(FindSDL)
if(SDL_FOUND)
message(STATUS "SDL FOUND")
endif()