How to build without the ROS build tools

How to build without the ROS build tools#

In the installation instruction, we make use of two build tools from the ROS. Here we explain their role and how to build navground without them.

Colcon#

Colcon is a tool to build a collection of package. It takes care of building them in separate directories to avoid conflicts and in the correct order to avoid missing dependencies. It handles C++ packages using CMake and Python packages using setuptools. It merges all builds in a single install directory together with scripts like install/setup.bash to setup the environment (i.e., PYTHONPATH, PATH, and so on).

Once navground is built using colcon, there are no runtime dependencies, except for the need to setup the environment: the install directory can be moved where we like and running navground does not require colcon to be installed.

Using colcon is typical in ROS 2 development. Even without ROS, it facilitates handling collection of packages. We recommend using it to users that want to extend navground, in particular if using C++. Yet, it is not needed to build navground.

Building navground without colcon#

To build navground without colcon, we just need to call the (native) build system.

C++ packages#

We can manually compile and install all the packages

cwd=$PWD
build=$cwd/build
CMAKE_INSTALL_PREFIX=$cwd/install
packages="
argparse
eigen3
yaml-cpp
geos
HighFive
hdf5
pybind11
navground/navground_core
navground/navground_sim
navground/navground_examples
navground/navground_examples_yaml
navground/navground_core_py
navground/navground_sim_py"
for package in ${packages}; do
  echo "----------- building $package -----------"
  mkdir -p $build/$package
  cd $build/$package
  cmake $cwd/src/$package -DBUILD_TESTING=OFF -DCMAKE_BUILD_TYPE=Release
  cmake --build . -j10
  cmake --install . --prefix $CMAKE_INSTALL_PREFIX
  cd $cwd
  echo "------------ built $package -------------"
done

Then, export the plugin and the library path

$ export DYLD_FALLBACK_LIBRARY_PATH=`pwd`/lib
$ export NAVGROUND_PLUGINS_PREFIX=`pwd`:$NAVGROUND_PLUGINS_PREFIX

Python packages#

We recommend using a virtual environment. Then, call

$ pip install <path_to_the_python_package> --prefix install

for any Pure Python package you want to install to install, like

$ pip install src/navground/navground_examples_py --prefix install

Then, export the Python path

$ export PYTHONPATH=`pwd`/install/lib/python3.<XX>/site-packages

Ament#

Ament provides packages to simplify the management of collection of packages. For navground, we make use of three ament packages if available:

  • ament_cmake is a collection of cmake modules which implement common functionalities like exporting targets;

  • ament_index_cpp is a c++ library to interact with the ament resource index, which is a way for packages to share resources (like navground plugins);

  • ament_package is a Python package to keep track of installed packages and is needed by ament_cmake.

Like for colcon, using ament is expected in ROS 2 but it is not necessary to build navground. In fact, you don’t need to change anything to build without ament, just don’t install it or specify the option -DWITH_AMENT=OFF when building navground_core.

When ament is not used, navground plugins are registered on a ad-hoc index. This is the reason why, when not using colcon, we need to export the index location:

$ export NAVGROUND_PLUGINS_PREFIX=`pwd`:$NAVGROUND_PLUGINS_PREFIX
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