SDL_envvars

Name

SDL_envvars -- SDL environment variables

Synopsis

#include "SDL_getenv.h"

...
putenv("name=value") ;
...
const char* myvalue = getenv("name") ;
...

Description

Maps getenv() and putenv() to SDL_getenv() and SDL_putenv() macros respectively (if needed).

Several environment variables are available to modify the behaviour of SDL. Using these variables isn't recommened and the names and presence of these variables aren't guaranteed from one release to the next. However, they can be very useful for debugging purposes.

These routines are intended for debugging/testing features in the SDL environment. They're not meant to (and do not) provide portable access to OS environment variables.

Video

SDL_FBACCEL
If set to 0, disable hardware acceleration in the linux fbcon driver.
SDL_FBDEV
Frame buffer device to use in the linux fbcon driver, instead of /dev/fb0
SDL_FULLSCREEN_UPDATE
In the ps2gs driver, sets the SDL_ASYNCBLIT flag on the display surface.
SDL_VIDEODRIVER
Selects the video driver for SDL to use. Possible values, in the order they are tried if this variable is not set:
SDL_VIDEO_CENTERED

If set, tries to center the SDL window when running in X11 windowed mode, or using the CyberGrafix driver.

SDL_VIDEO_WINDOW_POS

Set window position. The value should be a string on the form: "x,y"

SDL_VIDEO_GL_DRIVER
The openGL driver (shared library) to use for X11. Default is libGL.so.1
SDL_VIDEO_X11_DGAMOUSE
With XFree86, enables use of DGA mouse if set.
SDL_VIDEO_X11_MOUSEACCEL
For X11, sets the mouse acceleration. The value should be a string on the form:

  • "n/d/t"

    where n and d are the acceleration numerator/denumerators (so mouse movement is accelerated by n/d), and t is the threshold above which acceleration applies (counted as number of pixels the mouse moves at once).

SDL_VIDEO_X11_NODIRECTCOLOR

If set, don't attempt to use DirectColor visuals even if they are present. (SDL will use them otherwise for gamma correction). This is needed with older X servers when using the XVideo extension.

SDL_VIDEO_X11_VISUALID
ID of an X11 visual to use, overriding SDL's default visual selection algorithm. It can be in decimal or in hex (prefixed by 0x).
SDL_VIDEO_X11_WMCLASS
The name and class for the X11 window's WM_CLASS property (both use the same value), overriding the default.
SDL_VIDEO_YUV_DIRECT

If set, display YUV overlay directly on the video surface if possible, instead of on the surface passed to SDL_CreateYUVOverlay.

SDL_VIDEO_YUV_HWACCEL
If not set or set to a nonzero value, SDL will attempt to use hardware YUV acceleration for video playback.
SDL_WINDOWID
For X11 or Win32, contains the ID number of the window to be used by SDL instead of creating its own window. Either in decimal or in hex (prefixed by 0x).

Events/Input

SDL_MOUSE_RELATIVE
If set to 0, do not use mouse relative mode in X11. The default is to use it if the mouse is hidden and input is grabbed.
SDL_MOUSEDEV
The mouse device to use for the linux fbcon driver. If not set, SDL first tries to use GPM in repeater mode, then various other devices (/dev/pcaux, /dev/adbmouse, /dev/mouse etc).
SDL_MOUSEDEV_IMPS2
If set, SDL will not try to auto-detect the IMPS/2 protocol of a PS/2 mouse but use it right away. For the fbcon and ps2gs drivers.
SDL_MOUSEDRV
For the linux fbcon driver: if set to ELO, use the ELO touchscreen controller as a pointer device
SDL_NO_RAWKBD
For the libvga driver: If set, do not attempt to put the keyboard in raw mode.
SDL_NOMOUSE
If set, the linux fbcon driver will not use a mouse at all.

Audio

AUDIODEV
The audio device to use, if SDL_PATH_DSP isn't set.
SDL_AUDIODRIVER
Selects the audio driver for SDL to use. Possible values, in the order they are tried if this variable is not set:

  • openbsd

    (OpenBSD)

    dsp

    OSS /dev/dsp (no DMA): Linux, Solaris, BSD etc)

    dma

    OSS /dev/dsp (DMA): Linux, Solaris, BSD etc)

    alsa

    ALSA (Linux)

    pulse

    PulseAudio (POSIX, Win32)

    qsa-nto

    QNX6 QSA-NTO audio (QNX)

    audio

    Unix style /dev/audio: (SunOS, Solaris etc)

    AL

    Irix DMedia audio (Irix)

    artsc

    aRts (Analog Realtime Synthesizer)

    esd

    Enlightenment Sound Daemon

    nas

    Network Audio System (POSIX)

    dsound

    DirectSound (Win32)

    waveout

    Windows WaveOut (Win32)

    paud

    Paudio (AIX)

    baudio

    BSoundPlayer (BeOS)

    coreaudio

    MacOS X CoreAudio (MacOS X)

    sndmgr

    MacOS SoundManager 3.0 (old MacOS)

    mint_gsxb

    MiNT GSXB audio driver

    mint_mcsn

    MiNT MCSN audio driver

    mint_stfa

    MiNT STFA audio driver

    mint_xbios

    MiNT XBIOS audio driver

    mint_dma8

    MiNT DMA 8 bits audio driver

    disk

    output to file (all platforms)

    dummy

    dummy driver (no output)

    dcaudio

    Dreamcast AICA audio

    nds

    Nintendo DS audio

    waveout

    Tru64 MME WaveOut

    dart

    OS/2 Direct Audio RouTines (DART)

    epoc

    EPOC streaming audio
SDL_DISKAUDIOFILE
The name of the output file for the "disk" audio driver. If not set, the name sdlaudio.raw is used.
SDL_DISKAUDIODELAY
For the "disk" audio driver, how long to wait (in ms) before writing a full sound buffer. The default is 150 ms.
SDL_DSP_NOSELECT

For some audio drivers (alsa, paud, dma and dsp), don't use select() but a timed method instead. May cure some audio problems, or cause others.

SDL_PATH_DSP
The audio device to use. If not set, SDL tries AUDIODEV and then a platform-dependent default value (/dev/audio on Solaris, /dev/dsp on Linux etc).

CD-ROM

SDL_CDROM
A colon-separated list of CD-ROM devices to use, in addition to the standard devices (typically /dev/cdrom, platform-dependent).

Debugging

SDL_DEBUG

If set, causes every call to SDL_SetError (that is, every time SDL signals an error) to also print an error message on stderr.

Joystick

SDL_JOYSTICK_DEVICE
Joystick device to use in the linux joystick driver, in addition to the usual: /dev/js*, /dev/input/event*, /dev/input/js*
SDL_LINUX_JOYSTICK
Special joystick configuration string for linux. The format is:
  • "name numaxes numhats numballs"

    where name is the name string of the joystick (possibly in single quotes), and the rest are the number of axes, hats and balls respectively.

Comments

Windows version strangeness

Don't know if this is common to all platforms but apparently on Windows these routines (getenv, putenv) operate on an internal environment maintained by SDL - not based on the windows environment vars. Question related to this came up on #SDL (irc.freenode.net) about SDL_VIDEO_CENTERED appearing not to work. I confirmed that it does work but you have to set it before creating your window using putenv. (I set it before SDL_Init in my test.) That worked on WinXP Pro.
-- cid 2005-01-09 01:22:50

SDL_VIDEODRIVER=dummy

If you need an event queue but don't want a real window, try putenv("SDL_VIDEODRIVER=dummy") before you call SDL_SetVideoMode. I find this useful in apps that use SDL facilities, but don't need a real video output device. Oh, and apparently you can use a 0x0 resolution to avoid to much memory from making the dummy window. Of course, the dummy driver can also be used for offscreen rendering like for an image converter and such.
-- LIM 2005-02-12 07:22:50

CategorySDLGeneral

SDL_envvars (last edited 2010-05-08 17:42:29 by cpe-066-026-236-130)