How do I configure cmake to link to prebuilt shared libraries?

Question

I have a project that includes a prebuilt version of opencv in a subdirectory. For example:

MyProject
* CMakeLists.txt
* src
* third_party
** CMakeLists.txt
** opencv
**** include
**** lib

I would like to link against the version of opencv located in the third_party directory. My question is, how do I inform CMake to link to the prebuilt dylib files in lib, and include the headers in the relevant opencv directory?

cmake_minimum_required(VERSION 2.8.9)
project (myproject)

include_directories(${CMAKE_SOURCE_DIR}/third_party/opencv/include)
link_directories(${CMAKE_SOURCE_DIR}/third_party/opencv/lib)

file(GLOB SOURCES "*.cpp")

add_executable(myproject ${SOURCES})
target_link_libraries(myproject opencv_calib3d opencv_contrib opencv_core opencv_highgui opencv_features2d opencv_highgui opencv_imgproc)

Answer 1

I've given your example a try with CMake 3.3.2 on OS X 10.11 having XCode 7.0.1.

Using the link_directories() and target_link_libraries() approach suggested by @Tsyvarev seems to work without raising any linker warnings or errors (it finds the .dylib libraries I placed in the third_party directory).

Just a view hints, that hopefully could get you a start why it's not working on your Mac.

• With your code I get the following command line linker file (inside CMake's binary output directory):

  CMakeFiles/myproject.dir/src/link.txt

  /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++    
  -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk 
  -Wl,-search_paths_first 
  -Wl,-headerpad_max_install_names  
  CMakeFiles/myproject.dir/src/main.cpp.o  -o myproject  
  -L[...CMAKE_SOURCE_DIR...]/third_party/opencv/lib  
  -lopencv_calib3d -lopencv_contrib -lopencv_core -lopencv_highgui -lopencv_features2d -lopencv_highgui -lopencv_imgproc -lopencv_features2d -lopencv_imgproc 
  -Wl,-rpath,[...CMAKE_SOURCE_DIR...]/third_party/opencv/lib 
  

• You can try to give full library paths, because those are additionally checked by CMake itself and it gets more obvious what I link against. Here is a modified version of your example:

  CMakeLists.txt

  cmake_minimum_required(VERSION 2.8.9)
  project (myproject)
  
  include_directories(${CMAKE_SOURCE_DIR}/third_party/opencv/include)
  
  file(GLOB SOURCES "src/*.cpp")
  file(GLOB LIBRARIES "third_party/opencv/lib/*.dylib")
  message("LIBRARIES = ${LIBRARIES}")
  
  add_executable(myproject ${SOURCES})
  target_link_libraries(myproject ${LIBRARIES})  
  

  With this CMake just adds fully qualified paths (relative to my binary output directory) into the linker file. The -L and -l options are gone and you get "lines" like:

  ../third_party/opencv/lib/libopencv_calib3d.dylib 
  

Additional Q/A References

• OpenCV installation on Mac OS X
• How to use dylib file in application?
• CMake link_directories from library
• Force CMake to use the full library path