Developing on the codebase

Developing on the codebase#

The easiest way to work on the codebase is using the superbuild CMakeList.txt checked into fgmeta. If you are already familiar with CMake superbuilds, you can simply open the fgmeta as a workspace in your favourite smart editor (eg, Visual Studio Code), customize CMakeUserPresets.json to submit your local setup, and code, build and debug as normal. The steps below explain this process in more detail.

  1. Clone fgmeta, then git submodule init fgdata flightgear simgear. If you’re on Windows, also git submodule init windows-3rd-party. We’re explicitly listing the submodules here since some submodules don’t make sense for most people, and clutter up the build folder.

  2. Update the submodules; this takes some time since initial cloning of FGData is slow: git submodule update --remote

  3. Clone our forked OpenSceneGraph from https://gitlab.com/flightgear/openscenegraph (pick a location outside fgmeta)

  4. Build OpenSceneGraph and install into a suitable local prefix outside fgmeta; for example specify ~/FGFS/osg-build as the build directory and ~/FGFS/osg-dist as the CMAKE_INSTALL_PREFIX. (Again make sure you don’t use the system install prefix of /usr for installation, that will cause problems or overwrite your distro OpenSceneGraph)

  5. Open the fgmeta directory as a workspace in your favourite C++ IDE : VS Code, CLion, etc.

  6. Copy CMakeUserPreset-example.json to CMakeUserPresets.json and modify to suit. Notably, you should set CMAKE_PREFIX_PATH to include the prefix you used for OpenSceneGraph. You will probably also need to include the path to your Qt installation, if you want to use the launcher, but this is optional and often not needed for development work.

  • on macOS, you are recommended to download the most recent macos-3rd-party archive from GitLab, eg from: https://gitlab.com/flightgear/macos-3rd-party/-/artifacts : pass the location of the extracted files to CMAKE_PREFIX_PATH alongside any other paths. This is the easiest way to get the dependencies which are not available via Homebrew, such as PLIB and OpenAL-soft.

  1. Modern IDEs will detect updates to the CMake presets file and re-run the CMake configuration step, e.g., if you have installed the VS Code CMake integration plugin.

  2. Build the code: the super-build will build both SimGear and FlightGear

Day-to-day development#

  • code-indexing should work across both SimGear and FlightGear

  • no need to run any installation steps, the super-build handles dependencies correctly, eg if you edit a SimGear file the correct FlightGear pieces will rebuild

  • set breakpoints in the code as needed

  • update the flightgear and simgear modules as needed : note that fgmeta’s next branch does not receive commits to track the submodules, we assume developers track the HEAD of next for simgear and flightgear repositories.

  • create e.g., launch.json entries as needed (if using VS Code) to facilitate debugging

Invoking CMake manually#

If you use an editor that doesn’t detect CMake projects automatically, you can manually invoke CMake to create the build, and use cmake --build to build.

For example: cmake -S fgmeta -B build-fgmeta --preset MyPreset (assuming you named your preset MyPreset, of course)