Game Programming with the Simple DirectMedia Layer

Put the library behind Tux Racer and the Linux version of Civilization into your game.

Simple DirectMedia Layer (SDL, www.libsdl.org) is a simple, yet powerful, cross-platform game and multimedia development library. The library was developed by Sam Latinga while he was working for Loki Software, Inc. and was used in their commercial game projects. SDL was developed to meet the needs of game developers working in a multi-OS environment and was used in the Linux versions of Maelstrom, Hopkins FBI, Civilization: Call to Power, Descent 2, MythII: Soulblighter, Railroad Tycoon II, Tux Racer and many more. The SDL web site lists hundreds of games and applications written using SDL.

SDL officially supports Linux, Windows, BeOS, Mac OS, Mac OS X, FreeBSD, OpenBSD, BSD/OS, Solaris and IRIX. SDL also works with Windows CE, AmigaOS, Atari, QNX, NetBSD, AIX, Tru64 UNIX and SymbianOS. However, those OSes are not yet officially supported. This means if you write your application using SDL, you can port it with minimal rework to all those OSes. SDL provides a portable way to write games and multimedia applications on every major OS currently in use.

Installing SDL

If you are using a recent version of Linux, you probably have a complete SDL installation. In fact, a quick check of /usr/bin using ldd on my Red Hat 8.0 system found eight programs that depend on SDL.

The following commands show whether the SDL libraries and C/C++ include files are installed on your system:

locate SDL.h
locate libSDL
locate sdl-config

If all of these commands report the file was found, most likely you have a complete SDL installation, and you need only to make sure it is up to date. The sdl-config program checks the SDL version and acquires compile and link flags for your SDL applications. If sdl-config was found, run:

sdl-config --version
to see which version of SDL you have. If sdl-config reports a version less than 1.2.4, you should install newer libraries. Like most open-source projects, SDL is under constant development, so if you are using SDL for development, check for new versions regularly or join one of the SDL mailing lists to keep track of library updates.

If SDL is not installed, you need to download and install it. Your distribution probably has precompiled SDL packages, so you can check your regular source of packages first. If it's up to date, the easiest way to get started is to install the devel or dev packages for SDL from your distribution.

The file sdl-install.sh included with the source code used in this article is a shell script that downloads and installs version 1.2.5 of SDL and all its add-on libraries. The script must be run as root in the directory where you want the source for SDL. The script downloads the following:

If you don't use sdl-install.sh, visit the web pages listed above, download the files, unpack them and follow the instructions in the appropriate README files to install the libraries. Test your new installation by running:

sdl-config --version
If it doesn't run or gives a version number lower than the version you installed, the installation didn't work. In my experience, this happens when I don't follow the instructions or leave an old version of SDL installed in a different place. If locate sdl-config lists more than one location, either delete the old SDL installation, something I hate to do, or re-install over the old version. The sdl-install.sh file shows how to use ./configure --prefix to install SDL anywhere you want, but it's safest and easiest to install in the default location.

SDL documentation can be found at www.libsdl.org/docs.php. On-line documents are at sdldoc.csn.ul.ie. Support library documentation is either linked from their download pages, included with the source code or embedded in the .h files. Sample programs are included with SDL, and its support libraries are great starting places for your own projects.

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