using cmake to make header files descendants of the project's source directory

Question

As in Google C++ Style Guide is mentioned all of a project's header files should be listed as descendants of the project's source directory without use of UNIX directory shortcuts . (the current directory) or .. (the parent directory). How can I do that in my project that is shortly described below.

My project directory hierarchy is like this:

• GraphicsEngine
  • header_files.h
  • source_files.cc
  • CMakeLists.txt (1)
  • Light
    • CMakeLists.txt (2)
    • header_files.h
    • source_files.cc
  • Camera
    • CMakeLists.txt (3)
    • header_files.h
    • source_files.cc
  • Core
    • CMakeLists.txt (4)
    • header_files.h
    • source_files.cc

These are contents of CMakeLists.txt files:

CMakeLists.txt (1)

add_library(GraphicsEngineLib source_files.cc)
target_link_libraries(GraphicsEngineLib LightLib CameraLib CoreLib)
add_subdirectory(Light)
add_subdirectory(Camera)
add_subdirectory(Core)

CMakeLists.txt (2)

add_library(LightLib source_files.cc)

CMakeLists.txt (3)

add_library(CameraLib source_files.cc)

CMakeLists.txt (4)

add_library(CoreLib source_files.cc)

Now when for example I want to include header files from Camera folder in to files in Core folder, I have to use ../Camera/header_file.h but I want to use GraphicsEngine/Camera/header_file.h. How can I do this?

Answer 1

What I have done in the past is to set this in the top level CMakeLists.txt (which should be in your GraphicsEngine directory):

SET(PROJECT_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/..")

INCLUDE_DIRECTORIES(
  ${PROJECT_ROOT}
)

where according to this , CMAKE_CURRENT_SOURCE_DIR is

this is the directory where the currently processed CMakeLists.txt is located in

Note that by defining Project_Root in this way, your GraphicsEngine project can also #include headers from sister projects to GraphicsEngine .

Hope this helps.