Simple DirectMedia Layer

Sam Lantinga created the library, first releasing it in early 1998, while working for Loki Software. He got the idea while porting a Windows application to Macintosh. He then used SDL to port Doom to BeOS (see Doom source ports). Several other free libraries were developed to work alongside SDL, such as SMPEG and OpenAL. He also founded Galaxy Gameworks in 2008 to help commercially support SDL, although the company plans are currently on hold due to time constraints.[10]

Soon after putting Galaxy Gameworks on hold, Lantinga announced that SDL 1.3 (which would then later become SDL 2.0) would be licensed under the zlib License.[11] Lantinga announced SDL 2.0 on 14 July 2012, at the same time announcing that he was joining Valve, the first version of which was announced the same day he joined the company.[12] Lantinga announced the stable release of SDL 2.0.0 on 13 August 2013.[13]

SDL 2.0 is a major update to the SDL 1.2 codebase with a different, not backwards-compatible[14] API. It replaces several parts of the 1.2 API with more general support for multiple input and output options. Some feature additions include multiple window support, hardware-accelerated 2D graphics, and better Unicode support.[15]

Support for Mir and Wayland was added in SDL 2.0.2[16] and enabled by default in SDL 2.0.4.[17] Version 2.0.4 also provided better support for Android.[18]

SDL is a wrapper around the operating-system-specific functions that the game needs to access. The only purpose of SDL is to provide a common framework for accessing these functions for multiple operating systems (cross-platform).[19] SDL provides support for 2D pixel operations, sound, file access, event handling, timing and threading. It is often used to complement OpenGL by setting up the graphical output and providing mouse and keyboard input, since OpenGL comprises only rendering.

A game using the Simple DirectMedia Layer will not automatically run on every operating system; further adaptations must be applied. These are reduced to the minimum, since SDL also contains a few abstraction APIs for frequent functions offered by an operating system.

The syntax of SDL is function-based: all operations done in SDL are done by passing parameters to subroutines (functions). Special structures are also used to store the specific information SDL needs to handle. SDL functions are categorized under several different subsystems.

Supported back-ends

Abstraction layers of several SDL platforms

Because of the way SDL is designed, much of its source code is split into separate modules for each operating system, to make calls to the underlying system. When SDL is compiled, the appropriate modules are selected for the target system. The following back-ends are available:[3]

• GDI back-end for Microsoft Windows.
• DirectX back-end; older SDL 1.2 uses DirectX 7 by default, while 2.0 defaults to DirectX 9 and can access up to DirectX 11.
• Quartz back-end for macOS (dropped in 2.0).
• Metal back-end for macOS / iOS / tvOS since 2.0.8; older versions use OpenGL by default.[41][42]
• Xlib back-end for X11-based windowing system on various operating systems.[43]
• OpenGL contexts on various platforms.[44]
• EGL back-end when used in conjunction with Wayland-based windowing system.,[45] Raspberry Pi[46] and other systems.
• Vulkan contexts on platforms that support it.[6]
• sceGu back-end, a Sony OpenGL-like backend native to the PSP.

SDL 1.2 has support for RISC OS (dropped in 2.0).

An unofficial Sixel back-end is available for SDL 1.2.[47]

The Rockbox MP3 player firmware also distributes a version of SDL 1.2, which is used to run games such as Quake.[48]

Workshop on SDL, University of Cádiz

Over the years SDL was used for many commercial and non-commercial video game projects. For instance, MobyGames listed 120 games using SDL in 2013,[49] and the SDL website itself listed around 700 games in 2012.[50] Important commercial examples are Angry Birds,[51] Unreal Tournament, and games developed using Valve's Source Engine, which uses SDL extensively for cross-platform compatibility; ones from the open-source domain are OpenTTD,[52] The Battle for Wesnoth[53] or Freeciv.[54]

The cross-platform game releases of the popular Humble Indie Bundles for Linux, Mac and Android are often SDL-based.

SDL is also often used for later ports on new platforms with legacy code. For instance, the PC game Homeworld was ported to the Pandora handheld[55] and Jagged Alliance 2 for Android[56] via SDL.

Also, several non video game programs use SDL; examples are the emulators, such as DOSBox, FUSE ZX Spectrum emulator and VisualBoyAdvance.

There were several books written for development with SDL (see further readings).

SDL is used in university courses teaching multimedia and computer science, for instance, in a workshop about game programming using libSDL at the University of Cadiz in 2010, or a Game Design discipline at UTFPR (Ponta Grossa campus) in 2015.

• Alberto García Serrano: Programación de videojuegos en SDL, Ediversitas, ISBN 84-95836-08-4 (Spanish)
• Ernest Pazera: Focus On SDL, Muska & Lipman/Premier-Trade, ISBN 1-59200-030-4
• Ron Penton: Data Structures for Game Programmers, Muska & Lipman/Premier-Trade, ISBN 1-931841-94-2 (game programming examples with SDL)
• John R. Hall: Programming Linux Games, No Starch, ISBN 1-886411-49-2 (First SDL book, by Loki Games, archived online version: PDF at the Wayback Machine (archived 22 January 2003), LaTex sources at the Wayback Machine (archived 14 February 2003))

• Official website