[SOLVED] Unable to link imgui correctly as a library in CMAKE

[bensubytes]

Hi, I am fairly new to c++ and imgui.
I have a few external libraries which I managed to link correctly, but with imgui I am unable to do so and get the "imgui.lib" could not be found error.

This is the CMakeLists.txt in the imgui folder, which i think is the one with a problem:

cmake_minimum_required(VERSION 3.0)
project(gl3_wp18)

set(CMAKE_CXX_STANDARD)

include_directories(imgui)

This is the CMakeLists.txt in my game folder

cmake_minimum_required(VERSION 3.18)

#set variables for source files
set(SOURCE_FILES
        src/main.cpp
        src/rendering/Shader.cpp
        src/rendering/Shader.h
        src/Assets.h
        src/rendering/VBO.cpp
        src/rendering/VBO.cpp
        src/rendering/EBO.h
        src/rendering/EBO.cpp
        src/rendering/EBO.cpp
        src/rendering/VAO.h
        src/rendering/VAO.cpp
        src/rendering/Texture.h
        src/rendering/Texture.cpp
        src/rendering/SpriteRenderer.h
        src/rendering/SpriteRenderer.cpp
        src/Game.h
        src/Game.cpp
        src/rendering/ResourceManager.h
        src/rendering/ResourceManager.cpp
        src/entities/TileColors.h
        src/entities/TileColors.h
        src/entities/TileColors.cpp
        src/GuiWindow.h
        src/GuiWindow.cpp
        ../../extern/imgui/imgui_impl_opengl3.cpp
        ../../extern/imgui/imconfig.h
        ../../extern/imgui/imgui_impl_opengl3.h
        ../../extern/imgui/imgui_impl_opengl3_loader.h
        ../../extern/imgui/imgui.h
        ../../extern/imgui/imgui.cpp
        ../../extern/imgui/imgui_impl_glfw.h
        ../../extern/imgui/imgui_impl_glfw.cpp
        ../../extern/imgui/imgui_internal.h

)


#set executable name
set(EXE_FILE Game)

#add the executable target
add_executable(${EXE_FILE} ${SOURCE_FILES})

#require C++ 17 compiler
target_compile_features(${EXE_FILE} PRIVATE cxx_std_17)

#link with dependencies
target_link_libraries(${EXE_FILE} PRIVATE glad glfw glm soloud tinygltf nlohmann_json::nlohmann_json imgui)

target_compile_definitions(${EXE_FILE} PRIVATE ASSET_ROOT=./assets/)

#copy assets to output directory before build
add_custom_command(TARGET ${EXE_FILE} PRE_BUILD
        COMMAND ${CMAKE_COMMAND} -E copy_directory
        ${CMAKE_SOURCE_DIR}/assets $<TARGET_FILE_DIR:${EXE_FILE}>/assets)

And this is my overall CMakeLists.txt:

cmake_minimum_required(VERSION 3.21)
project(gl3_wp18)

set(CMAKE_CXX_STANDARD 17)

add_subdirectory(extern/glad)
add_subdirectory(extern/glfw)
add_subdirectory(extern/glm)
add_subdirectory(extern/soloud)
add_subdirectory(extern/tinygltf)
add_subdirectory(extern/imgui)


set(JSON_BuildTests OFF CACHE INTERNAL "")
add_subdirectory(extern/nlohmann_json)

add_subdirectory(game)

Lastly, here is a snap of my project structure to make it a bit clearer:

I appreciate any input, the guides online are not very helpful or barely existent regarding cmake and imgui, thank you!

EDIT: Somebody was able to give me a helping hand with the CMake, here is how it's supposed to look like, incase somebody has similar issues:

cmake_minimum_required(VERSION 3.18)
project(imgui)

# set glad header files variable
file(GLOB_RECURSE SOURCE_FILES *.h *.cpp)

# add glad as a static library
add_library(imgui STATIC ${SOURCE_FILES})

# require C++ 17 compiler
target_compile_features(imgui PRIVATE cxx_std_17)

target_link_libraries(imgui PRIVATE glfw)

# specify the include directory for this static libray
target_include_directories(imgui PUBLIC .)

[nicolasnoble]

If you are specifying the sources of imgui to compile with your own project files like you're doing in your set(SOURCE_FILES, then there should be no need to specify imgui in target_link_libraries, as it wouldn't be a library: it'd be just part of your main binary itself.

[bensubytes]

I would prefer to have it as an actual library, I added them in the set(SOURCE_FILES as I thought that might help but it didn't. When I remove them it doesn't really change anything.
Here is the full error by the way

[1/1] Linking CXX executable game\Game.exe
FAILED: game/Game.exe 
cmd.exe /C "cmd.exe /C "cd /D C:\Users\Bengisu\Desktop\09-gl3-cetinkaya\code\cmake-build-debug\game && C:\Users\Bengisu\AppData\Local\JetBrains\Toolbox\apps\CLion\ch-0\232.9921.42\bin\cmake\win\x64\bin\cmake.exe -E copy_directory C:/Users/Bengisu/Desktop/09-gl3-cetinkaya/code/assets C:/Users/Bengisu/Desktop/09-gl3-cetinkaya/code/cmake-build-debug/game/assets && cd C:\Users\Bengisu\Desktop\09-gl3-cetinkaya\code\cmake-build-debug" && C:\Users\Bengisu\AppData\Local\JetBrains\Toolbox\apps\CLion\ch-0\232.9921.42\bin\cmake\win\x64\bin\cmake.exe -E vs_link_exe --intdir=game\CMakeFiles\Game.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\mt.exe --manifests  -- C:\PROGRA~1\MICROS~4\2022\COMMUN~1\VC\Tools\MSVC\1438~1.331\bin\Hostx64\x64\link.exe /nologo game\CMakeFiles\Game.dir\src\main.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Shader.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\EBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VAO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Texture.cpp.obj game\CMakeFiles\Game.dir\src\rendering\SpriteRenderer.cpp.obj game\CMakeFiles\Game.dir\src\Game.cpp.obj game\CMakeFiles\Game.dir\src\rendering\ResourceManager.cpp.obj game\CMakeFiles\Game.dir\src\entities\TileColors.cpp.obj game\CMakeFiles\Game.dir\src\GuiWindow.cpp.obj  /out:game\Game.exe /implib:game\Game.lib /pdb:game\Game.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL /subsystem:console  extern\glad\glad.lib  extern\glfw\src\glfw3.lib  extern\soloud\src\soloud.lib  extern\tinygltf\tinygltf.lib  imgui.lib  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
LINK Pass 1: command "C:\PROGRA~1\MICROS~4\2022\COMMUN~1\VC\Tools\MSVC\1438~1.331\bin\Hostx64\x64\link.exe /nologo game\CMakeFiles\Game.dir\src\main.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Shader.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\EBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VAO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Texture.cpp.obj game\CMakeFiles\Game.dir\src\rendering\SpriteRenderer.cpp.obj game\CMakeFiles\Game.dir\src\Game.cpp.obj game\CMakeFiles\Game.dir\src\rendering\ResourceManager.cpp.obj game\CMakeFiles\Game.dir\src\entities\TileColors.cpp.obj game\CMakeFiles\Game.dir\src\GuiWindow.cpp.obj /out:game\Game.exe /implib:game\Game.lib /pdb:game\Game.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL /subsystem:console extern\glad\glad.lib extern\glfw\src\glfw3.lib extern\soloud\src\soloud.lib extern\tinygltf\tinygltf.lib imgui.lib kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTFILE:game\CMakeFiles\Game.dir/intermediate.manifest game\CMakeFiles\Game.dir/manifest.res" failed (exit code 1104) with the following output:
LINK : fatal error LNK1104: File "imgui.lib" cannot be opened.
ninja: build stopped: subcommand failed.

[ocornut]

Then you have to create the library but that’s entirely a cmake logic/syntax problem, not really an imgui problem. As nicolas pointed out, you way you are currently setup is requesting to link with a library but not creating the library.

Please note this is a problem you are creating yourself here. Although it’s perfectly fine to face it to increase your understanding of cmake, it’s not required.

I myself don’t know how to use cmake so I cannot help much.

[bensubytes]

Thank you for your help, maybe somebody else will know what's missing in the CMakeFile for imgui. If not I will use it just via set(SOURCE_FILES thank you both!

[ocornut]

You are not actually specifying what your link error is, but 99.9% of the time the link error tells you the files you forgot to link. If you see the Getting Started guide it tells to compile and link all cpp files into the root directly and you are not doing.

[ocornut]

As Nicolas mentioned there’s an issue with your lib setup but i believe it’s find if you don’t make it a lib and just compile it as part of your project. However you do need all the cpp files, not only imgui.cpp and backend files.

[bensubytes]

This is the full error:

[1/1] Linking CXX executable game\Game.exe
FAILED: game/Game.exe 
cmd.exe /C "cmd.exe /C "cd /D C:\Users\Bengisu\Desktop\09-gl3-cetinkaya\code\cmake-build-debug\game && C:\Users\Bengisu\AppData\Local\JetBrains\Toolbox\apps\CLion\ch-0\232.9921.42\bin\cmake\win\x64\bin\cmake.exe -E copy_directory C:/Users/Bengisu/Desktop/09-gl3-cetinkaya/code/assets C:/Users/Bengisu/Desktop/09-gl3-cetinkaya/code/cmake-build-debug/game/assets && cd C:\Users\Bengisu\Desktop\09-gl3-cetinkaya\code\cmake-build-debug" && C:\Users\Bengisu\AppData\Local\JetBrains\Toolbox\apps\CLion\ch-0\232.9921.42\bin\cmake\win\x64\bin\cmake.exe -E vs_link_exe --intdir=game\CMakeFiles\Game.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\100226~1.0\x64\mt.exe --manifests  -- C:\PROGRA~1\MICROS~4\2022\COMMUN~1\VC\Tools\MSVC\1438~1.331\bin\Hostx64\x64\link.exe /nologo game\CMakeFiles\Game.dir\src\main.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Shader.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\EBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VAO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Texture.cpp.obj game\CMakeFiles\Game.dir\src\rendering\SpriteRenderer.cpp.obj game\CMakeFiles\Game.dir\src\Game.cpp.obj game\CMakeFiles\Game.dir\src\rendering\ResourceManager.cpp.obj game\CMakeFiles\Game.dir\src\entities\TileColors.cpp.obj game\CMakeFiles\Game.dir\src\GuiWindow.cpp.obj  /out:game\Game.exe /implib:game\Game.lib /pdb:game\Game.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL /subsystem:console  extern\glad\glad.lib  extern\glfw\src\glfw3.lib  extern\soloud\src\soloud.lib  extern\tinygltf\tinygltf.lib  imgui.lib  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
LINK Pass 1: command "C:\PROGRA~1\MICROS~4\2022\COMMUN~1\VC\Tools\MSVC\1438~1.331\bin\Hostx64\x64\link.exe /nologo game\CMakeFiles\Game.dir\src\main.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Shader.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\EBO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\VAO.cpp.obj game\CMakeFiles\Game.dir\src\rendering\Texture.cpp.obj game\CMakeFiles\Game.dir\src\rendering\SpriteRenderer.cpp.obj game\CMakeFiles\Game.dir\src\Game.cpp.obj game\CMakeFiles\Game.dir\src\rendering\ResourceManager.cpp.obj game\CMakeFiles\Game.dir\src\entities\TileColors.cpp.obj game\CMakeFiles\Game.dir\src\GuiWindow.cpp.obj /out:game\Game.exe /implib:game\Game.lib /pdb:game\Game.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL /subsystem:console extern\glad\glad.lib extern\glfw\src\glfw3.lib extern\soloud\src\soloud.lib extern\tinygltf\tinygltf.lib imgui.lib kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTFILE:game\CMakeFiles\Game.dir/intermediate.manifest game\CMakeFiles\Game.dir/manifest.res" failed (exit code 1104) with the following output:
LINK : fatal error LNK1104: File "imgui.lib" cannot be opened.
ninja: build stopped: subcommand failed.

Do you mean the imgui.tables, widgets files and so on which are in the master directory or do I need more? Even if I add those I get this error, the only difference is that it doesn't happen at [1/1] but at the second step like so:

[1/2] Building CXX object game\CMakeFiles\Game.dir\src\main.cpp.obj
[2/2] Linking CXX executable game\Game.exe
FAILED: game/Game.exe 

and the rest is the same.

[ocornut]

Do you mean the imgui.tables, widgets files and so on which are in the master directory

Yes, as this is what is stated in the getting started guide.
If you still have a problem the remaining problem is elsewhere.