How to structure a cmake project with different 3rd-party libraries

Question

I'm new with cmake and try to create a small project which needs some 3rd-party libs. I would like to have the libs as git repos to always be up-to-date. Some libs are just .cpp and .hpp files (glad, imgui) and others are cmake projects (glfw, glm).

The idea is to have a 3rd-party project with all the libs as a kind of subprojects and a sandbox project which uses the libs and includes etc. And I would like to use modern cmake code which is not installing something outside the framework structure.

Folder structure:

Framework
|--3rd_party
|  |--glad
|  |  |--include
|  |  |--src
|  |--glfw-master
|  |  |--...
|  |  |--CMakeLists.txt
|  |--glm-master
|  |  |--..
|  |  |--CMakeLists.txt
|  |--imgui-master
|  |  |--*.cpp
|  |  |--*.hpp
|  |  |--examples
|  |  |  |--*.cpp
|  |  |  |--*.hpp
|  |--CMakeLists.txt
|--sandbox
|  |--main.cpp
|  |--CMakeLists.txt
|--CMakeLists.txt

So I created this folder structure and also some CMakeLists:

CMakeLists.txt (Framework)

cmake_minimum_required(VERSION 3.10)

project(Framework)

add_subdirectory("3rd_party")
add_subdirectory("sandbox")

CMakeLists.txt (3rd_party)

#GLFW
set(GLFW_BUILD_DOCS OFF CACHE BOOL "" FORCE)
set(GLFW_BUILD_TESTS OFF CACHE BOOL "" FORCE)
set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
add_subdirectory(glfw-master)

# GLM
set(GLM_TEST_ENABLE OFF CACHE BOOL "" FORCE)
add_subdirectory(glm-master)

# Glad
add_library(
    Glad STATIC
    "glad/src/glad.c"
)

target_include_directories(Glad PUBLIC "glad/include")

# ImGui
add_compile_definitions(IMGUI_IMPL_OPENGL_LOADER_GLAD=1)

set(IMGUI_SOURCES
    "imgui-master/imgui.cpp"
    "imgui-master/imgui_demo.cpp"
    "imgui-master/imgui_draw.cpp"
    "imgui-master/imgui_widgets.cpp"
    "imgui-master/examples/imgui_impl_glfw.cpp"
    "imgui-master/examples/imgui_impl_opengl3.cpp"
)

set(IMGUI_HEADERS
    "imgui-master/imconfig.h"
    "imgui-master/imgui.h"
    "imgui-master/imgui_internal.h"
    "imgui-master/imstb_rectpack.h"
    "imgui-master/imstb_textedit.h"
    "imgui-master/imstb_truetype.h"
    "imgui-master/examples/imgui_impl_glfw.h"
    "imgui-master/examples/imgui_impl_opengl3.h"
)

add_library(
    ImGui STATIC
    ${IMGUI_SOURCES}
    ${IMGUI_HEADERS}
)

target_include_directories(ImGui PUBLIC "imgui-master" "glfw-master/include" "glad/include")

CMakeLists.txt (sandbox)

project(Sandbox)

find_package(OpenGL REQUIRED)

add_executable(sandbox main.cpp)

# OpenGL
target_include_directories(Sandbox PUBLIC ${OPENGL_INCLUDE_DIR})
target_include_directories(Sandbox PUBLIC external)

# Glfw
target_include_directories(Sandbox PUBLIC "../3rd_party/glfw-master/include")

# Link libs
target_link_libraries(Sandbox PUBLIC
           ${OPENGL_LIBRARIES}
           "../3rd_party/glfw-master/src/Debug/glfw3"
           Glad
           ImGui
           glm_static
)

The code works but not as I expect. At first I know it's a little bit ugly maybe there is a better way to handle the path for includes and sources but the bigger problem is project structure. For example, when I build it for ms vs studio I have three solutions

./framework.sln
./sandbox/sandbox.sln
./3rd_party/glfw-master/glfw.sln

And glad, glm and imgui are part of sandbox.sln

What I would like to have is a solution with two sub-solutions sandbox and 3rd_party which also has sub-solutions or projects for all the libs.

So is it possible at all and if yes how can I create such a structure with cmake?

boss0r boss0r · Accepted Answer · 2019-08-28T20:31:33

After further investigation and a lot of try and error with CMake, I guess I started with wrong expectations and some missunderstandings.

It is not possible to get a useful solution/project structure for Visual Studio from CMake files because all CMake-projects will result in a VS-solution and all add_library or add_executable will be a VS-project. If I want to create a CMake-project for my framework and add GLFW as third party, which also creates a CMake-project, it will end with two different VS-solutions and bang the structure is gone. I think that is why Microsoft introduced a special open context for CMake files in Visual Studio.

If a project is opened with this context, the "solution" viewer shows the folder structure of the project. And that is more or less what I expected in the beginning.

There is also an option to switch the view to see all CMake targets (exec, libs, ...).

I also "upgraded" my CMakeLists. I use different ways to add the third party libs:

add_subdirectory for libs with CMakeLists like GLFW
add_library and INTERFACE for header-only libs like glm
add_library STATIC for static libs like ImGui (in my case)

The includes for Sandbox are provided by the public interface of the libs and the build/dependency order is given by order in target_link_libraries.

I hope that is was helpul and will spare you a lot of time ;)

Cheers! boss0r

CMakeLists.txt (Framework)

cmake_minimum_required(VERSION 3.10)

project(OpenGL_Framework
    VERSION 0.0.1
    LANGUAGES CXX C    # C for GLFW
)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

add_subdirectory(ThirdParty)
add_subdirectory(Sandbox)

CMakeLists.txt (3rd_party)

# GLFW
set(GLFW_LIB_NAME "GLFW")
set(GLFW_INC_PATH ${GLFW_LIB_NAME}/include)

set(GLFW_BUILD_DOCS     OFF CACHE BOOL "" FORCE)
set(GLFW_BUILD_TESTS    OFF CACHE BOOL "" FORCE)
set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
#set(GLFW_VULKAN_STATIC  OFF CACHE BOOL "" FORCE)    # OFF by default
#set(BUILD_SHARED_LIBS   OFF CACHE BOOL "" FORCE)    # OFF by default
set(GLFW_INSTALL        OFF CACHE BOOL "" FORCE)

add_subdirectory(${GLFW_LIB_NAME})

# spdlog
set(SPDLOG_LIB_NAME "spdlog")

set(SPDLOG_MASTER_PROJECT OFF CACHE BOOL "" FORCE)

add_subdirectory(${SPDLOG_LIB_NAME})

# OR
#set(SPDLOG_LIB_NAME "spdlog")
#set(SPDLOG_SRC_PATH ${SPDLOG_LIB_NAME}/src)
#set(SPDLOG_INC_PATH ${SPDLOG_LIB_NAME}/include)

#add_library(${SPDLOG_LIB_NAME}
#    STATIC
#        ${SPDLOG_SRC_PATH}/spdlog.cpp
#)

#target_include_directories(${SPDLOG_LIB_NAME}
#    PUBLIC
#        ${SPDLOG_INC_PATH})

# glm
set(GLM_LIB_NAME "glm")
set(GLM_INC_PATH ${GLM_LIB_NAME}/glm)

add_library(${GLM_LIB_NAME} INTERFACE)

target_include_directories(${GLM_LIB_NAME}
    INTERFACE
        ${GLM_INC_PATH}
)

# OR
#set(GLM_LIB_NAME "glm")
#set(GLM_INC_PATH ${GLM_LIB_NAME}/glm)

#set(GLM_TEST_ENABLE OFF CACHE BOOL "" FORCE)

#add_subdirectory(${GLM_LIB_NAME})

#target_include_directories(${GLM_LIB_NAME}
#    PUBLIC
#        $(GLM_INC_PATH)
#)

# Glad
set(GLAD_LIB_NAME "Glad")
set(GLAD_SRC_PATH "${GLAD_LIB_NAME}/src")
set(GLAD_INC_PATH "${GLAD_LIB_NAME}/include")

add_library( ${GLAD_LIB_NAME}
    STATIC
        "${GLAD_SRC_PATH}/glad.c"
)

target_include_directories(${GLAD_LIB_NAME}
    PUBLIC
        "${GLAD_INC_PATH}"
)

# ImGui
set(IMGUI_LIB_NAME "ImGui")

set(IMGUI_SOURCES
    "${IMGUI_LIB_NAME}/imgui.cpp"
    "${IMGUI_LIB_NAME}/imgui_demo.cpp"
    "${IMGUI_LIB_NAME}/imgui_draw.cpp"
    "${IMGUI_LIB_NAME}/imgui_widgets.cpp"
    "${IMGUI_LIB_NAME}/examples/imgui_impl_glfw.cpp"
    "${IMGUI_LIB_NAME}/examples/imgui_impl_opengl3.cpp"
)

set(IMGUI_HEADERS
    "${IMGUI_LIB_NAME}/imconfig.h"
    "${IMGUI_LIB_NAME}/imgui.h"
    "${IMGUI_LIB_NAME}/imgui_internal.h"
    "${IMGUI_LIB_NAME}/imstb_rectpack.h"
    "${IMGUI_LIB_NAME}/imstb_textedit.h"
    "${IMGUI_LIB_NAME}/imstb_truetype.h"
    "${IMGUI_LIB_NAME}/examples/imgui_impl_glfw.h"
    "${IMGUI_LIB_NAME}/examples/imgui_impl_opengl3.h"
)

set(IMGUI_INC_PATH "${IMGUI_LIB_NAME}/")

add_library(${IMGUI_LIB_NAME}
    STATIC
        ${IMGUI_SOURCES}
        ${IMGUI_HEADERS}
)

target_compile_definitions(${IMGUI_LIB_NAME}
    PRIVATE
        IMGUI_IMPL_OPENGL_LOADER_GLAD=1
)

target_include_directories(${IMGUI_LIB_NAME}
    PUBLIC
        "${IMGUI_INC_PATH}"
        "${GLFW_INC_PATH}"
        "${GLAD_INC_PATH}"
)

CMakeLists.txt (sandbox)

project(Sandbox)

find_package(OpenGL REQUIRED)

add_executable(${PROJECT_NAME} Sandbox.cpp)

target_include_directories(${PROJECT_NAME}
    PUBLIC
        external
        ${OPENGL_INCLUDE_DIR}
)

target_link_libraries(${PROJECT_NAME}
    PUBLIC
        ${OPENGL_gl_LIBRARY}
        glfw
        Glad
        ImGui
        glm
        #glm_static    # if build with add_subdirectory
        spdlog::spdlog
)

How to structure a cmake project with different 3rd-party libraries

1 Answers