modernize cmake syntax

[mamoll]

This PR mirrors the changes in ompl/ompl#1066.

The pkg-config file ompl.pc that is generated is actually broken. The same is true for the ompl repo. I'm thinking we should just remove the png-config related stuff.

I noticed that in the ompl repo, libompl gets installed in CMAKE_INSTALL_DATAROOTDIR (i.e., /usr/share) rather than CMAKE_INSTALL_LIBDIR (i.e. /usr/lib). That is fixed in this PR for omplapp, but if this is right, we need to make the same change in ompl.

[mamoll]

@Ryanf55 FYSA

[Ryanf55]

Nice improvement!

[Ryanf55]

Do you want to just call target_link_libraries on ompl::ompl?

[Ryanf55]

Will this conflict with the other export if someone installs both libraries into the same folder (a colcon user would share the install folder between multiple repos)? Usually, I've seen ${PROJECT_NAME}Export to prevent conflicts.

[Ryanf55]

Suggested change

	target_link_libraries(ompl_benchmark ${OMPLAPP_LIBRARIES} ompl ompl_app_base Boost::program_options)
	target_link_libraries(ompl_benchmark ompl::omplapp ompl ompl_app_base Boost::program_options)

If you can, try linking to an ALIAS targets for all of these. They don't all exist, but are easily created for the internal ones..

[Ryanf55]

I tried your PR in an isolated environment, and it didn't compile. After cloning and changing directory into the repo:

docker run --net host -v $(pwd):/ws -w /ws -it ubuntu:22.04 bash
apt update
apt install -y \
    build-essential libboost-filesystem-dev libboost-serialization-dev libboost-system-dev libboost-program-options-dev \
    cmake libeigen3-dev libassimp-dev libfcl-dev
cmake -B build/Release
cmake --build build/Release/ --parallel $(nproc)

Results in

[ 87%] Built target demo_MultiLevelPlanningRigidBody2D
[ 88%] Building CXX object src/omplapp/CMakeFiles/ompl_app_base.dir/apps/detail/appUtil.cpp.o
[ 88%] Linking CXX executable ../../bin/demo_MultiLevelPlanningRigidBody3D
[ 88%] Built target demo_MultiLevelPlanningRigidBody3D
[ 88%] Building CXX object src/omplapp/CMakeFiles/ompl_app_base.dir/geometry/RigidBodyGeometry.cpp.o
gmake[2]: *** No rule to make target '/usr/lib/x86_64-linux-gnu/libz.so', needed by 'lib/libompl_app_base.so.1.6.0'.  Stop.
gmake[2]: *** Waiting for unfinished jobs....
[ 88%] Building CXX object src/omplapp/CMakeFiles/ompl_app_base.dir/geometry/detail/assimpUtil.cpp.o
[ 88%] Linking CXX executable ../../bin/demo_Koules
[ 88%] Linking CXX executable ../../bin/demo_MultiLevelPlanningHyperCube
[ 88%] Built target demo_Koules
[ 88%] Built target demo_MultiLevelPlanningHyperCube
[ 89%] Linking CXX executable ../../bin/demo_ConstrainedPlanningKinematicChain
[ 89%] Built target demo_ConstrainedPlanningKinematicChain
[ 89%] Linking CXX executable ../../bin/demo_ConstrainedPlanningSphere
[ 89%] Built target demo_ConstrainedPlanningSphere
[ 90%] Linking CXX executable ../../bin/demo_ConstrainedPlanningTorus
[ 90%] Built target demo_ConstrainedPlanningTorus
[ 90%] Linking CXX executable ../../bin/demo_MultiLevelPlanningKinematicChain
[ 90%] Built target demo_MultiLevelPlanningKinematicChain
[ 90%] Linking CXX executable ../../bin/demo_ConstrainedPlanningImplicitChain
[ 90%] Built target demo_ConstrainedPlanningImplicitChain
[ 90%] Linking CXX executable ../../bin/demo_MultiLevelPlanningHyperCubeBenchmark
[ 90%] Built target demo_MultiLevelPlanningHyperCubeBenchmark
[ 90%] Linking CXX executable ../../bin/demo_ConstrainedPlanningImplicitParallel
[ 90%] Built target demo_ConstrainedPlanningImplicitParallel
gmake[1]: *** [CMakeFiles/Makefile2:1298: src/omplapp/CMakeFiles/ompl_app_base.dir/all] Error 2

Note I use slightly different build instructions rather than calling make directly, but it works much the same, with less typing.

[mamoll]

The docker build error looks to me like libassimp-dev's Debian package is broken and doesn't declare a dependency on zlib1g-dev. Once you install the later, the build succeeds