Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

sdl_joystickgetaxis(3) [opensolaris man page]

SDL_JoystickGetAxis(3)						 SDL API Reference					    SDL_JoystickGetAxis(3)

NAME
SDL_JoystickGetAxis - Get the current state of an axis SYNOPSIS
#include "SDL.h" Sint16 SDL_JoystickGetAxis(SDL_Joystick *joystick, int axis); DESCRIPTION
SDL_JoystickGetAxis returns the current state of the given axis on the given joystick. On most modern joysticks the X axis is usually represented by axis 0 and the Y axis by axis 1. The value returned by SDL_JoystickGetAxis is a signed integer (-32768 to 32768) representing the current position of the axis, it maybe necessary to impose certain tolerances on these values to account for jitter. It is worth noting that some joysticks use axes 2 and 3 for extra buttons. RETURN VALUE
Returns a 16-bit signed integer representing the current position of the axis. EXAMPLES
Sint16 x_move, y_move; SDL_Joystick *joy1; . . x_move=SDL_JoystickGetAxis(joy1, 0); y_move=SDL_JoystickGetAxis(joy1, 1); SEE ALSO
SDL_JoystickNumAxes SDL
Tue 11 Sep 2001, 23:00 SDL_JoystickGetAxis(3)

Check Out this Related Man Page

jscal(1)						      General Commands Manual							  jscal(1)

NAME
jscal - joystick calibration and remapping program SYNOPSIS
jscal [options] <device-name> DESCRIPTION
jscal calibrates joysticks and maps joystick axes and buttons. Calibrating a joystick ensures the positions on the various axes are cor- rectly interpreted. Mapping axes and buttons allows the meanings of the joystick's axes and buttons to be redefined. On Debian systems the calibration settings can be stored and later applied automatically using the jscal-store command. OPTIONS
-c, --calibrate Calibrate the joystick. -h, --help Print out a summary of available options. -s, --set-correction <nb_axes,type,precision,coefficients,...> Sets correction to specified values. For each axis, specify the correction type (0 for none, 1 for "broken line"), the precision, and if necessary the correction coefficients ("broken line" corrections take four coefficients). -u, --set-mappings <nb_axes,axmap1,axmap2,...,nb_buttons,btnmap1,btnmap2,...> Sets axis and button mappings. n_of_buttons can be set to 0 to remap axes only. -t, --test-center Tests if the joystick is correctly calibrated. Returns 2 if the axes are not calibrated, 3 if buttons were pressed, 1 if there was any other error, and 0 on success. -V, --version Prints the version numbers of the running joystick driver and that which jscal was compiled for. -p, --print-correction Prints the current correction settings. The format of the output is a jscal command line. -q, --print-mappings Prints the current axis and button mappings. The format of the output is a jscal command line. CALIBRATION
Using the Linux input system, joysticks are expected to produce values between -32767 and 32767 for axes, with 0 meaning the joystick is centred. Thus, full-left should produce -32767 on the X axis, full-right 32767 on the X axis, full-forward -32767 on the Y axis, and so on. Many joysticks and gamepads (especially older ones) are slightly mis-aligned; as a result they may not use the full range of values (for the extremes of the axes), or more annoyingly they may not give 0 when centred. Calibrating a joystick provides the kernel with informa- tion on a joystick's real behaviour, which allows the kernel to correct various joysticks' deficiencies and produce consistent output as far as joystick-using software is concerned. jstest(1) is useful to determine whether a joystick is calibrated: when run, it should produce all 0s when the joystick is at rest, and each axis should be able to produce the values -32767 and 32767. Analog joysticks should produce values in between 0 and the extremes, but this is not necessary; digital directional pads work fine with only the three values. SEE ALSO
ffset(1), jstest(1), jscal-store(1). AUTHORS
jscal was written by Vojtech Pavlik and improved by many others; see the linuxconsole tools documentation for details. This manual page was written by Stephen Kitt <steve@sk2.org>, for the Debian GNU/Linux system (but may be used by others). jscal Jul 11, 2010 jscal(1)
Man Page