CODEWITHSUNDEEP
c++cmake
DocRobson
DocRobson

Reputation: 125

CMake does not set variables for g2o

On macOS 11.0, I downloaded and built g2o (https://github.com/RainerKuemmerle/g2o) and installed it using cmake --install . I then tried to include it in my own project via CMake like this (CMakeLists.txt):

cmake_minimum_required (VERSION 3.14)
project (MY-PROJECT)

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# PkgConfig to find other packages easily
find_package(PkgConfig REQUIRED) 

# find required modules
pkg_check_modules(OpenCV REQUIRED opencv4)
find_package(Eigen3 REQUIRED)
find_package(OpenGL REQUIRED)
find_package(G2O REQUIRED)

message(STATUS "G2O FOUND: ")
message(STATUS ${G2O_FOUND}) # prints 1

message(STATUS "G2O INCLUDE DIRS: ")
message(STATUS ${G2O_INCLUDE_DIRS}) # prints nothing

message(STATUS "G2O Link Libraries: ")
message(STATUS ${G2O_LINK_LIBRARIES}) # prints nothing

message(STATUS "EIGEN3 INCLUDE DIRS: ")
message(STATUS ${EIGEN3_INCLUDE_DIRS}) # prints /usr/local/include/eigen3

CMake sets G2O_FOUND to 1, indicating that it successfully found g2o. However, the other two variables are not set, so the include- and library-files are not found. I solved this by adding

set(G2O_INCLUDE_DIRS
/usr/local/include)

set(G2O_LIBS
/usr/local/lib/libg2o_core.dylib
/usr/local/lib/libg2o_types_slam3d.dylib
#...
)

include_directories(
G2O_INCLUDE_DIRS  
)

target_link_libraries(
    MY-PROJECT
    ${G2O_LIBS}
)

to CMakeLists.txt, but I am still curious why CMake did find g2o but not set the variables accordingly.

Upvotes: 0

Views: 1289

Answers (1)

KamilCuk
KamilCuk

Reputation: 141688

why CMake did find g2o but not set the variables accordingly.

FindG2O.cmake does not set these variables, so they are not set. The variables checked for G2O_FOUND to be set are G2O_STUFF_LIBRARY AND G2O_CORE_LIBRARY AND G2O_INCLUDE_DIR AND G2O_SOLVERS_FOUND.

There is no rule that find_package has to set _LIBRARIES or _INCLUDE_DIRS variables - every package is a little different, consult that particular package. If writing FindXXX file, use interface or imported libraries instead of variables.

Upvotes: 1

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