This page contains information for packagers looking to package Principia for their Linux distro.
Some other metadata information can be found in the Principia metainfo file at packaging/se.principia_web.principia.metainfo.xml.
We use CMake for our build system which you would want to add as a buildtime dependency. Our documentation uses Ninja but using the regular CMake Makefile generator is fine too.
Principia relies on the following runtime dependencies:
None of these libraries are vendored, and the build system uses the versions provided by the system when building. You are welcome! :)
In addition to this Principia uses xdg-open for opening webpages from the game. Whether it can be assumed to exist on the base system or a dependency on xdg-utils should be added is up to you.
If you peek in src/ you may see that there are some more libraries we use that are vendored.
SDL_image and SDL_mixer are vendored to reduce the amount of libraries that are pulled in for our official Windows and Linux builds, as well as being used for the Android version. Devendoring these libraries should not cause any adverse effects and you are free to do so.
Principia has vendored versions of Lua 5.2, Luasocket and Box2D. Do not under any circumstances devendor these libraries, as they have modifications done to them for use with the game. Even if you manage to replace it with system libraries, the physics simulation will be significantly altered breaking existing levels and you will likely expose dangerous functions in the Lua scripting.
We understand the security concerns with vendoring libraries, and we proactively look out for potential vulnerabilities or other bugs that have been patched in upstream. If you are aware of any issues in the vendored libraries then please let us know.
Principia provides the usual metadata files for packaging such as an icon and desktop file, and it should be as easy as doing ninja install with DESTDIR pointed to your packaging system's package directory. It will install everything including the binary and game data in a way that the game can read data as long as the directory structure is kept, and as long as your distro follows the traditional Linux directory structure that should be all you need.
To be more detailed, Principia attempts to load the data folders data-pc and data-shared from the following locations:
./ (data directories are next to the executable)../ (data directories are one directory up relative to the executable)../share/principia/ (for an installed build)So while Principia would usually be installed at /usr/bin/principia and its data in /usr/share/principia/, the binary is relocatable and the prefix could be something completely else than /usr such as e.g. /usr/local or /packagesilo/principia. If your distro doesn't use /usr you probably are already aware of this.
Principia makes connections to principia-web by default. Inform the user of this network connectivity in the metadata of the package, if necessary. The source code for the website is available here licensed under the AGPLv3 license, and also see the Privacy Policy.
Do not patch out any of the game's network connectivity, a large part of the game is the community site where you can play and upload levels.
If you are still required to disable the network connectivity that happens by default, then please only replace the default community domain located in the top of populate_community_host() in src/src/main.cc with localhost or something else. This makes the player still able to play levels from level servers in their web browser and reactivate full network connectivity by putting a domain (e.g. principia-web.se) in community_host.txt in their Principia user folder.
Do not remove the update check. Principia does not automatically update, it simply shows a toast message on the main menu that a new version is available. The player deserves to be able to know if the packaged Principia they have installed is outdated, as it may make it impossible to play new levels made with newer versions when new features are added and the level version is increased.
When you've gotten Principia packaged for your distribution it would be great to hear from you, so the package can be added in a section on the download page.
Any kind of patches to the game that are general enough to be upstreamed to us are very welcome. Either open a pull request on Github or send an email to ROllerozxa linking to the patches and he can take a look at them.
