Simple DirectMedia Layer
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| Simple DirectMedia Layer | |
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<tr><td colspan="2" style="text-align: center;"> | |
| Use: | API
<tr><th>License:</th><td>GNU Lesser General Public License</td></tr> |
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| Website: | libsdl.org |
Simple DirectMedia Layer (SDL) is a cross-platform multimedia library written in C that creates an abstraction over various platforms' graphics, sound, and input APIs, allowing a developer to write a computer game or other multimedia application once and run it on many operating systems including GNU/Linux, Windows and Mac OS X. It manages video, events, digital audio, CD-ROM, sound, threads, shared object loading, networking and timers.
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[edit] History
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 appeared to work with SDL, such as SMPEG and OpenAL.
The SDL library has bindings with almost every programming language there is, from the popular (C++, Perl, Python (through pygame), Pascal etc.) to the less known (such as Euphoria or Pliant). This and the fact that it is open-source and licensed under the LGPL make SDL a common choice for many multimedia applications.
SDL itself is very simple; it merely acts as a thin, cross-platform wrapper, providing support for 2D pixel operations, sound, file access, event handling, timing, threading, and more. OpenGL is often used with SDL to provide fast 3D rendering. It is often thought of as a cross-platform DirectX, although it lacks some of its more advanced functionality. SDL instead has a huge number of third party extensions that make it easy to do more advanced functions.
The library is divided into several subsystems, namely the Video (handles both surface functions and OpenGL), Audio, CD-ROM, Joystick and Timer subsystems. Besides this basic, low-level support, there also are a few separate official libraries that provide some additional functionality. These comprise the "standard library", and are provided on the official website and included in the official documentation:
- SDL_image (provides an easy way to load today's most common image formats),
- SDL_mixer (complex audio functions, mainly for sound mixing)
- SDL_net (networking support)
- SDL_ttf (TrueType Font rendering support)
- SDL_rtf (simple Rich Text Format rendering).
[edit] Architecture
Image:SDL Layers.png SDL has the word "layer" in its title because it is actually a wrapper around operating-system-specific functionality. The chief purpose of SDL is to provide a common framework for accessing this functionality.
Because of the way SDL is designed, much the source code is split into separate modules for each operating system, in order to make calls to the underlying system. When SDL is compiled, the correct modules are selected for the target system.
On Microsoft Windows, SDL actually wraps around DirectX. Older versions used DirectX 5, but SDL 1.2 (the current stable release) requires DirectX 7 by default. Sam Lantinga has stated that he plans to use DirectX 8 in future SDL releases[1].
On X11 platforms, including Linux, SDL uses Xlib to communicate with the X11 system for graphics and events.
[edit] Syntax and subsystems
- Main article: SDL syntax
The syntax of SDL is function-based, all operations done in SDL are done by passing parameters to functions. Special structures are also used to store the specific information SDL needs to handle. There are a few different subsystems SDL categorizes its functions under:
- the Video, events and threads subsystem - this provides functionality for video, multi-threading, and event handling.
- the Audio subsystem - this provides audio functionality.
- the Time subsystem
- the Joystick subsystem
- the CD-ROM subsystem
[edit] Example Code (C)
// Headers
#include "SDL.h"
// Main function
int main( int argc, char* argv[] )
{
// Initialize SDL
if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 )
return( 1 );
// Delay 2 seconds
SDL_Delay( 2000 );
// Quit SDL
SDL_Quit();
// Return
return( 0 );
}
A very basic SDL program. It loads SDL subsystems, pauses for 2 seconds, closes SDL, then exits the program.
[edit] Games using SDL
See List of games using SDL for a more complete list
[edit] Extensions
- SMPEG - SDL MPEG Player Library
- Guichan and ParaGUI - Widget Sets
- GGI - a free cross-platform graphics interface
[edit] See also
</div>- Allegro
- OpenML
- DirectX
- OpenGL
- pygame [2] - a wrapper around SDL for Python
- SDL.NET - a .NET wrapper for SDL written in C#
- CRM32Pro - High level API built around SDL which provide you with all functions needed to develop games
[edit] External links
- SDL website
- SDL.NET homepage
- GameDev - a site dedicated to game development, programming, et cetera. Discussion space can be found here on gamedev.
- The Game Programming Wiki's SDL Tutorials
- The SDL Documentationcs:Simple DirectMedia Layer
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