CMake header files not being found in include - c++

Question

I have library, AprilTags, that uses cmake top build it.
I have another project AIV, that uses AprilTags. I want to keep the apriltags library inside of ~/aiv/apriltags but have another file, front_back_camera_demo that uses some of the files inside of AprilTags library.
So the file structure looks like
~/aiv/build/
/apriltags/CMakeLists.txt
/apriltags/AprilTags/TagDetector.h
/apriltags/AprilTags/*.h
/front_back_camera_demo.cpp
/CMakeLists.txt
When I run cmake on the top level CMakeLists.txt, it builds the AprilTags library successfully, but then I get a
front_back_camera_demo.cpp:72:35: fatal error: AprilTags/TagDetector.h: No such file or directory
error on the line where I include AprilTags/TagDetector.h
Here are the two relevant CMakeLists.txt:
Top level:
cmake_minimum_required(VERSION 2.6)
project(AIV)
add_subdirectory(apriltags)
add_executable(front_back_camera_demo front_back_camera_demo.cpp
Serial.cpp)
target_link_libraries(front_back_camera_demo apriltags)
Inside apriltags:
cmake_minimum_required(VERSION 2.6)
project(apriltags)
#add_definitions(-pg) #"-fopenmp)
# pull in the pods macros. See cmake/pods.cmake for documentation
set(POD_NAME apriltags)
include(cmake/pods.cmake)
file(GLOB SOURCE_FILES "src/*.cc")
include_directories(AprilTags . /opt/local/include)
add_library(apriltags ${SOURCE_FILES})
find_package(OpenCV)
include_directories(${OpenCV_INCLUDE_DIRS})
target_link_libraries(apriltags ${OpenCV_LIBS}) #-pg) #-fopenmp)
pods_use_pkg_config_packages(apriltags eigen3)
if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
target_link_libraries(apriltags -L/opt/local/lib/) # MacPorts
special treatment...
else (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
pods_use_pkg_config_packages(apriltags libv4l2)
endif (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
pods_install_libraries(apriltags)
file(GLOB header_files "AprilTags/*.h")
pods_install_headers(${header_files} DESTINATION AprilTags/)
pods_install_pkg_config_file(apriltags
LIBS -lapriltags
REQUIRES eigen3 opencv2
VERSION 1.0.0)
add_subdirectory(example)
What am I doing wrong?

Answer 1

Prefer the target_* commands.
apriltags/CMakeLists.txt:
target_include_directories(apriltags
PUBLIC
"${CMAKE_CURRENT_SOURCE_DIR}"
PRIVATE
"${CMAKE_CURRENT_SOURCE_DIR}/AprilTags"
/opt/local/include)
That says, everything that uses the apriltags target will be able to access any includes in ".", that apriltags can also use "." and only apriltags itself uses content under the "AprilTags" and "/opt/local/include" directories.
If you really know what you are doing, you can get even more fine-grained by using generator expressions, but that is not necessary here to get it working.