gnubg_web is a port of GNU Backgammon to the web, with nearly all the features of the original.

A Javascript GUI replaces the GTK-based GUI in the original.

Building the source

gnubg_web is built using Emscripten, which compiles the gnubg C source code and the glib libraries used by it, into Javascript and Webassembly. Webassembly is supported by the latest modern browsers.

Instructions for building and testing:

1. Install Emscripten. Then activate the PATH and other environment variables by running source /path/to/emscripten/emsdk_env.sh. For more information on this step, see the Emscripten documentation. The latest version of Emscripten which has been tested to successfully build gnubg_web is 2.0.23.

2. Execute ./build.sh from within the gnubg_web directory.

3. This will generate several files within a build directory. To test the build locally, start a webserver inside the build directory. If you have Python 3 installed, a simple way is to run python -m http.server 8000 from within the build directory. (For Python 2, use python -m SimpleHTTPServer 8000.) Then go to http://localhost:8000/gnubg_web.html from your browser. Note that opening the gnubg_web.html file directly from your browser probably won't work, because of CORS restrictions for local files on the latest browsers. If you really cannot get anything else to work, you can look up how to disable such restrictions in your browser, but this is not recommended.

What has been modified from the original GNU Backgammon code?

The gnubg subdirectory contains the original source code for GNU Backgammon version 1.05.000, with the following changes:

1. Some source files are not needed in the web version, and have been moved to a removed_files subdirectory within gnubg, which doesn't get compiled when building gnubg_web. This includes the GTK-related files (since the GTK GUI has been replaced by a Javascript GUI), openurl (for opening files within a browser) and external (for connecting to an external player).

2. A few modifications to the original source have been made, primarily to interact with the Javascript GUI properly. These changes are marked with #ifdef WEB or #ifndef WEB blocks.

3. The packaged_files subdirectory consists of several data files needed. These are the neural network weights gnubg.wd, the one-sided bearoff database gnubg_os0.bd, all the match equity tables in the met subdirectory, and some startup settings in .gnubg/gnubgrc needed by the web version. Note that due to its size, the two-sided bearoff database gnubg_ts0.bd is currently not packaged. However, it is included in the gnubg subdirectory. If you wish to package it, you can copy this file to the packaged_files subdirectory before building.

4. Sounds have been disabled. Although it probably wouldn't be difficult to get them working using Javascript, it didn't seem worth the increased binary size (which increases the download time when serving the binary over the web).

The glib source code

GNU Backgammon uses the glib libraries extensively. Because Emscripten needs to build everything from scratch, a copy of the glib 2.62.0 source code is included in the subdirectory glib/glib-2.62.0, configured to work with Emscripten. Many of glib's necessary configuration parameters (#defines) have been consolidated into config.h within gnubg.

Not all of glib is needed for compiling gnubg_web, so some of the *.c source files have been renamed as *.c_do_not_compile. If you make some changes that need one of the files, you should rename them back to *.c. However, note that some of the source files -- particularly anything related to Windows, such as gwin32 -- will not work in the Emscripten environment.