find_package (OpenGL QUIET)

if (OPENGL_gl_LIBRARY)
    if (IMGUI_IMPL_OPENGL2)
        add_library (imgui-opengl2 OBJECT
            "${CMAKE_CURRENT_LIST_DIR}/imgui_impl_opengl2.cpp"
        )

        target_link_libraries (imgui-opengl2 PUBLIC
            imgui
            "${OPENGL_gl_LIBRARY}"
        )

        target_include_directories (imgui-opengl2 PUBLIC "${CMAKE_CURRENT_LIST_DIR}")
        target_include_directories (imgui-opengl2 SYSTEM PUBLIC "${OPENGL_INCLUDE_DIR}")
    endif ()

    if (IMGUI_IMPL_OPENGL)
        find_package (GLEW)

        if (GLEW_DIR)
            add_library (imgui-opengl OBJECT
                "${CMAKE_CURRENT_LIST_DIR}/imgui_impl_opengl3.cpp"
            )

            target_link_libraries (imgui-opengl PUBLIC
                imgui
                "${OPENGL_gl_LIBRARY}"
                glew
            )

            target_include_directories (imgui-opengl PUBLIC "${CMAKE_CURRENT_LIST_DIR}")
            target_include_directories (imgui-opengl SYSTEM PUBLIC "${OPENGL_INCLUDE_DIR}")
        else ()
            message (WARNING "IMGUI_IMPL_OPENGL set to ON but GLEW could not be found")
        endif ()
    endif ()
else ()
    message (WARNING "IMGUI_IMPL_OPENGL and/or IMGUI_IMPL_OPENGL2 set to ON but OpenGL could not be found")
endif ()