How to make a lib before making the program in CMAKE? - c++

I would like to be able to dynamically compile a library that will be used by my project before compiling my project.
I am setting up a Vulkan project in C++ (with Clion) and would like it to be multi-platforms, I am using GLFW3.3 to make that happen.
Instead of building my library for each platform and putting the libs and .h in a folder that will be linked through the CMakeLists.txt, I would like to be able to CMAKE+make the library, then put the lib and .h where they need to be and then start compiling my program that will be using those.
GLFW has a working CMakeLists.txt (I manage to make it manually through the console) but I don't know how to tell CMAKE to make it etc.
I am used to using CMake to define path to libs and includes but my last project what also multi-platforms and I didn't like the way I handled the library (build manually etc).
So I am looking for a way in CMake to do everything at once even if it will take time to do so but I have no idea how that works.

Take a look at how Glitter does it:
option(GLFW_BUILD_DOCS OFF)
option(GLFW_BUILD_EXAMPLES OFF)
option(GLFW_BUILD_TESTS OFF)
add_subdirectory(Glitter/Vendor/glfw)
target_link_libraries(${PROJECT_NAME} ... glfw)
They just include the CMakeLists.txt file that GLFW provides and depend on it for the main target.

Related

Correct way of adding libraries to C++ project

In my project I want to include some libraries. For now at least GLFW and GLEW.
I want them to be added automatically whenever I clone my repo. So my idea was to add those libraries as git-submodules and include them via my CMakeList. Both libs have a CMakeList which made me think I can easily add them with cmake.
But I don't know how to add those. I use CLion since I am not experienced with cmake or C++ in general. I tried to include them via add_subdirectory() and just treat them as normal code but then GLEW cant find header files, I tried to include them via add_library() but cmake does not use GLFWs CMakeList.
What would be the correct way of including libraries?

How do I properly link my libraries in my project using CMake?

I'm currently learning CMake and I'm trying to create my first test project. I'm able to get a simple project up and running in visual studio via CMake. However, I'm having trouble trying to add a library. I've read some guides and things but I keep getting errors. Basically, I'm trying to link SDL libraries (a game programming library) in my sample project. I've placed these libraries in a top level, 'ThirdParty' folder. Here is what my CmakeLists.txt file looks like in my top level directory:
cmake_minimum_required(VERSION 2.8.11)
project(Hello)
#Find necessary header files
find_path(SDL_INCLUDE_DIR SDL.h HINTS ${CMAKE_SOURCE_DIR}/ThirdParty/SDL2/include/)
#Find necessary library files
find_library(SDL_LIB_DIR SDL2 HINTS ${CMAKE_SOURCE_DIR}/ThirdParty/SDL2/lib/x86)
find_library(SDLMAIN_LIB_DIR SDLmain HINTS ${CMAKE_SOURCE_DIR}/ThirdParty/SDL2/lib/x86)
#Add/Link files to project
include_directories(${SDL_INCLUDE_DIR})
target_link_libraries(Test PUBLIC ${SDL_LIB_DIR})
target_link_libraries(Test PUBLIC ${SDLMAIN_LIB_DIR})
add_executable(Test "${CMAKE_SOURCE_DIR}/Source/Main.cpp")
I'm not 100 percent sure of the HINTS parameter, but I saw it used on another thread. Anyway, here's the error I keep getting:
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
SDLMAIN_LIB_DIR
linked by target "Test" in directory C:/Users/Jason/Desktop/Test
What am I doing wrong and how do I properly link libraries in CMake?
In cmake, you first create the executable, and then you link it to a library
You have to understand how finding libraries and packages works in CMake. Typically the way it works is that you use find_library or find_package, and then cmake will set some variables that you can use to link to/use the library.
I'm not familiar with SDL, but by googling a little bit about it, I would say this is how it should look like:
find_file(SDL2_INCLUDE_DIR NAME SDL.h HINTS SDL2)
find_library(SDL2_LIBRARY NAME SDL2)
add_executable(MyExec main.cpp)
target_include_directories(MyExec ${SDL2_INCLUDE_DIR})
target_link_libraries(MyExec ${SDL2_LIBRARY})
That find_library will set the variables SDL2_INCLUDE_DIR and SDL2_LIBRARY, which you can use to link to SDL and add its includes to your project.

creating a static library and linking using Cmake

I have a application which need to use two libraries (pugixml and lua) and need to be an multi-platform build capable. I am trying to use Cmake for this. Since I have three different solution (two for creating static libraries and one solution which actually uses that libraries). So far what I do is run Cmake for those two libraries and copy those static libraries manually to the lib folder into application and run cmake again.
I need to reduce the three step and make it as a single step so that I can handle the multi-platform build in a single shot.
I need to know, should we need to create a dynamic link library or shared library or static library for these kind of operation?
And need help on how to do it. I tried creating the source folder of pugixml and copy the cpp/hpp/h file and wrote a cmakelists file like
set(HEADERS pugixml.hpp pugiconfig.hpp)
set(SOURCES ${HEADERS} pugixml.cpp)
add_library(pugixmlLib STATIC ${SOURCES})
target_link_libraries(pugixmlLib pugixml)
On the solution I could see my application project and pugixml project, but on my application project linker property I could find pugixml library.

Using Cmake, how do I prevent library sources from being included in my IDE?

Using a bunch of different libraries in my project (from GitHub sources, not precompiled), I add them to my target like this in my root CMakeLists.txt file:
add_subdirectory(lib/glew-1.13.0/build/cmake)
include_directories(SYSTEM ${PROJECT_SOURCE_DIR}/lib/glew-1.13.0/include/)
...
target_link_libraries(MyApp glew ${GLEW_LIBRARIES} ... )
However, you can see from the screenshot below that Xcode includes all of the sources for those libraries in my project, which makes an insanely long list that I have to scroll through to find my code.
I have tried the EXCLUDE_FROM_ALL flag in the add_subdirectory command, which removes the library sources from my Xcode project, but then I cannot compile my project because Xcode doesn't compile the library at all.
Additionally, Xcode gives me tons of warnings from the libraries that I don't really care about. Using the SYSTEM flag with the include_directories command doesn't fix it.
What's the best way to solve this? Should I be compiling my libraries as a completely separate part of my build process rather than compiling them with my executable?
I'm not sure how it will work, but try this:
turn on the USE_FOLDERS in your root CMakeLists.txt
set_property(GLOBAL PROPERTY USE_FOLDERS ON)
And then after you've added all the projects, set the FOLDER target property on all of the third party libraries:
set_property(TARGET target1 target2 ...
PROPERTY FOLDER "ThirdPartyLibs")
Being unfamiliar with C++, I thought that all of my libraries should be compiled along with my project every time. I ended up solving this by writing a shell script that precompiles all of my libraries once as static libraries, and now I don't have to worry about their sources in my IDE, plus I get faster compile times.

Create standalone executable with CMake

I need to build a standalone executable. The main problem is that this project relies on dll which I previously built on my system.
When I create the executable there should not be a dependence from these dll so I need to know if I can include them somehow in the program. To compile I'm currently using CMake which I believe is the best solution, but I haven't figured a way to accomplish this task yet.
Right now in my CMakeLists.txt file I do the following:
find_package(ITK REQUIRED)
include(${ITK_USE_FILE})
add_executable(myexe myexe.cxx)
target_link_libraries(myexe
${ITK_LIBRARIES} )
I omitted some instructions to focus on what's most important. When I compile it, it correctly works but it is not standalone as it still keeps using the dll (also tried with .a) installed on my system.
Thanks
A DLL is by nature dynamically linked to at runtime. Your only option is to use a static library (.lib on windows .