SDL_envvars

Name

SDL_envvars -- SDL environment variables

Description

Not a function, set using setenv()

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.

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

Selectes the video driver for SDL to use. Possible values, in the order they are tried if this variable is not set:

x11

dga

(the XFree86 DGA2)

nanox

(Linux)

fbcon

(Linux)

directfb

(Linux)

ps2gs

(Playstation 2)

ggi

vgl

(BSD)

svgalib

(Linux)

aalib

directx

(Win32)

windib

(Win32)

bwindow

(BeOS)

toolbox

(MacOS Classic)

DSp

(MacOS Classic)

Quartz

(Mac OS X)

CGX

(Amiga)

photon

(QNX)

dummy

SDL_VIDEO_CENTERED

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

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_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.

SDL_NO_LOCK_KEYS

Disable CAPS-LOCK and NUM-LOCK suppression of down+up key events, suitable for games where the player needs these keys to do more than just toggle. A value of 1 will effect both CAPS-LOCK and NUM-LOCK. A value of 2 will effect only CAPS-LOCK. A value of 3 will effect only NUM-LOCK. All other values have no effect.

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: Linux, Solaris, BSD etc)

alsa

(Linux)

pulse

(PulseAudio daemon)

audio

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

AL

(Irix)

artsc

(ARTS audio daemon)

esd

(esound audio daemon)

nas

(NAS audio daemon)

dma

(OSS /dev/dsp, using DMA)

dsound

(Win32 DirectX)

waveout

(Win32 WaveOut)

baudio

(BeOS)

sndmgr

(MacOS SoundManager)

paud

(AIX)

AHI

(Amiga)

disk

(all; output to file)

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.