How can i link GLFW and Dear ImGUI in CMAKE

Question

the last few days i was messing with CMake, and everything worked fine, except that i can't find a way to link ImGUI with GLFW

Everything is build from source

Here is the error :

Consolidate compiler generated dependencies of target glad
[  2%] Built target glad
Consolidate compiler generated dependencies of target stb
[  5%] Built target stb
Consolidate compiler generated dependencies of target glfw
[ 29%] Built target glfw
Consolidate compiler generated dependencies of target imgui
[ 30%] Building CXX object CMakeFiles/imgui.dir/lib/imgui/imgui.cpp.o
[ 31%] Building CXX object CMakeFiles/imgui.dir/lib/imgui/imgui_demo.cpp.o
[ 33%] Building CXX object CMakeFiles/imgui.dir/lib/imgui/imgui_draw.cpp.o
[ 34%] Building CXX object CMakeFiles/imgui.dir/lib/imgui/imgui_tables.cpp.o
[ 36%] Building CXX object CMakeFiles/imgui.dir/lib/imgui/imgui_widgets.cpp.o
[ 37%] Building CXX object CMakeFiles/imgui.dir/lib/imgui/imgui_impl_glfw.cpp.o
/home/erik/Workspace/LearnOpenGL/lib/imgui/imgui_impl_glfw.cpp:45:10: fatal error: GLFW/glfw3.h: No such file or directory
   45 | #include <GLFW/glfw3.h>
      |          ^~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/imgui.dir/build.make:146: CMakeFiles/imgui.dir/lib/imgui/imgui_impl_glfw.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:228: CMakeFiles/imgui.dir/all] Error 2
make: *** [Makefile:156: all] Error 2

And here is my CMakeLists.txt :

cmake_minimum_required(VERSION 3.1)

project(LearnOpenGL)


set(SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/source")
set(LIB_DIR "${CMAKE_CURRENT_SOURCE_DIR}/lib")

set(SOURCES "${SRC_DIR}/Main.cpp"
    )


add_executable(${PROJECT_NAME} ${SOURCES})

target_include_directories(${PROJECT_NAME} PRIVATE "${SRC_DIR}")

set_property(TARGET ${PROJECT_NAME} PROPERTY CXX_STANDARD 11)


# GLFW

set(GLFW_DIR "${LIB_DIR}/glfw")

set(GLFW_BUILD_EXAMPLES OFF CACHE INTERNAL "Build the GLFW example programs")
set(GLFW_BUILD_TESTS OFF CACHE INTERNAL "Build the GLFW test programs")
set(GLFW_BUILD_DOCS OFF CACHE INTERNAL "Build the GLFW documentation")
set(GLFW_INSTALL OFF CACHE INTERNAL "Generate installation target")

add_subdirectory("${GLFW_DIR}")

target_link_libraries(${PROJECT_NAME} "glfw" "${GLFW_LIBRARIES}")
target_include_directories(${PROJECT_NAME} PRIVATE "${GLFW_DIR}/include")
target_compile_definitions(${PROJECT_NAME} PRIVATE "GLFW_INCLUDE_NONE")


# Glad

set(GLAD_DIR "${LIB_DIR}/glad")

add_library("glad" "${GLAD_DIR}/src/glad.c")

target_include_directories("glad" PRIVATE "${GLAD_DIR}/include")
target_include_directories(${PROJECT_NAME} PRIVATE "${GLAD_DIR}/include")
target_link_libraries(${PROJECT_NAME} "glad" "${CMAKE_DL_LIBS}")


# GLM 

set(GLM_DIR "${LIB_DIR}/glm")

add_subdirectory(${GLM_DIR})

target_link_libraries(${PROJECT_NAME} "glm")


# STB

set(STB_DIR "${LIB_DIR}/stb")

add_library("stb" "${STB_DIR}/src/stb_image.cpp")

target_include_directories("stb" PRIVATE "${STB_DIR}/include")
target_include_directories(${PROJECT_NAME} PRIVATE "${STB_DIR}/include")
target_link_libraries(${PROJECT_NAME} "stb" "${CMAKE_DL_LIBS}")


# Freetype

set(FREETYPE_DIR "${LIB_DIR}/freetype")

add_subdirectory("${FREETYPE_DIR}")

target_link_libraries(${PROJECT_NAME} "${FREETYPE_LIBRARIES}")
target_include_directories(${PROJECT_NAME} PRIVATE "${FREETYPE_DIR}/include")


# ImGUI

set(IMGUI_DIR "${LIB_DIR}/imgui")

add_library("imgui" "${IMGUI_DIR}/imgui.cpp"
                  "${IMGUI_DIR}/imgui_demo.cpp"
                  "${IMGUI_DIR}/imgui_draw.cpp"
                  "${IMGUI_DIR}/imgui_tables.cpp"
                  "${IMGUI_DIR}/imgui_widgets.cpp"
                  
                  "${IMGUI_DIR}/imgui_impl_glfw.cpp"
                  "${IMGUI_DIR}/imgui_impl_opengl3.cpp")

target_include_directories("imgui" PRIVATE "${IMGUI_DIR}")
target_include_directories(${PROJECT_NAME} PRIVATE "${IMGUI_DIR}")
target_link_libraries(${PROJECT_NAME} "imgui" "${CMAKE_DL_LIBS}")

And here is my folder construction

 1. build
 2. lib
    -  freetype
    -  glad
    -  glfw
    -  glm
    -  imgui
    -  stb
 3. source
    -  Main.cpp
 4. CMakeLists.txt

Here is my question : How i can tell imgui that glfw is already here and he can use it?

Thanks in advance

Answer 1

Your build should consist of nothing but the following:

cmake_minimum_required(VERSION 3.20)
project(LearnOpenGL)

## Find dependencies
find_package(glfw3 REQUIRED)
find_package(glad REQUIRED)
find_package(glm REQUIRED)
find_package(freetype REQUIRED)
find_package(imgui REQUIRED)

# stb does not have a CMake build, but is header-only
find_path(STB_INCLUDE_DIRS "stb.h") 

## Create main executable
add_executable(main source/Main.cpp)
target_include_directories(main 
  PRIVATE 
    ${STB_INCLUDE_DIRS}
    "${CMAKE_CURRENT_LIST_DIR}/source"
)
target_link_libraries(
  main
  PRIVATE
    freetype
    glfw
    glad::glad
    glm::glm
    imgui::imgui
)

If you aren't using CMake 3.20, (a) you should be, but (b) you can try with an earlier version. But never put a version below the one you test with. CMake is only backwards compatible, not forwards compatible.

If you only need freetype as a dependency of imgui, then you can remove the references to it in the CMakeLists.txt.

To build this, you'll want to use vcpkg. To that end, create a file called vcpkg.json next to your CMakeLists.txt with the following contents:

{
  "name": "learn-opengl",
  "version": "0.1.0",
  "dependencies": [
    "glfw3",
    "glad",
    "glm",
    "freetype",
    "stb",
    {
      "name": "imgui",
      "features": ["freetype", "glfw-binding", "opengl3-glad-binding"]
    }
  ]
}

This is just telling vcpkg which dependencies you want, and that you want imgui built with freetype support and the glfw bindings.

Then you just need to run three commands.

$ git clone https://github.com/microsoft/vcpkg.git
$ cmake -S . -B build -DCMAKE_BUILD_TYPE=Release \
        -DCMAKE_TOOLCHAIN_FILE=$PWD/vcpkg/scripts/buildsystems/vcpkg.cmake
$ cmake --build build

The only thing here that might be unexpected is setting CMAKE_TOOLCHAIN_FILE, this is just telling CMake to use vcpkg. The first time this runs, vcpkg will download your dependencies, build them, cache them in ~/.cache/vcpkg and install them into your build folder. Subsequent runs will build just your code.

This sequence successfully built your code for me on my Ubuntu 20.04 LTS machine.

---

To make this easier, consider creating a CMakePresets.json file, also in your root directory, with the following contents:

{
  "version": 2,
  "cmakeMinimumRequired": {
    "major": 3,
    "minor": 20,
    "patch": 0
  },
  "configurePresets": [
    {
      "name": "default",
      "displayName": "Default Config",
      "description": "Default build using Make and vcpkg",
      "generator": "Unix Makefiles",
      "binaryDir": "${sourceDir}/build",
      "cacheVariables": {
        "CMAKE_BUILD_TYPE": "Release",
        "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/vcpkg/scripts/buildsystems/vcpkg.cmake"
      }
    },
    {
      "name": "default-msvc",
      "displayName": "Default MSVC",
      "description": "Default build using Visual Studio and vcpkg",
      "generator": "Visual Studio 16 2019",
      "binaryDir": "${sourceDir}/build",
      "cacheVariables": {
        "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/vcpkg/scripts/buildsystems/vcpkg.cmake"
      }
    }
  ]
}

Then you can just run cmake --preset=default instead of the longer command above.