Mercurial > sdl-ios-xcode
annotate docs/html/sdljoystickgetaxis.html @ 896:b56dc586a5ef
Date: Tue, 16 Mar 2004 12:40:33 +0000
From: Alan Swanson
Subject: [SDL] [PATCH] Linux joystick evdev axis count fix
The event device configuration under Linux does not check the returned
ioctl value when reading the axis information. This means extra
undefined axes are returned.
Note, in EV_HandleEvents, the default for case EV_ABS is to return any
axis information which is fine as we have already checked for all valid
absolute axes. No new axes should be returned after opening the device.
(Unless, of course, the evdev allows closing and reassigning a new
device while in use and I can't believe that happens.)
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 16 May 2004 22:48:06 +0000 |
| parents | 355632dca928 |
| children |
| rev | line source |
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| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >SDL_JoystickGetAxis</TITLE | |
| 5 ><META | |
| 6 NAME="GENERATOR" | |
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
| 0 | 8 "><LINK |
| 9 REL="HOME" | |
| 10 TITLE="SDL Library Documentation" | |
| 11 HREF="index.html"><LINK | |
| 12 REL="UP" | |
| 13 TITLE="Joystick" | |
| 14 HREF="joystick.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="SDL_JoystickUpdate" | |
| 17 HREF="sdljoystickupdate.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="SDL_JoystickGetHat" | |
| 20 HREF="sdljoystickgethat.html"></HEAD | |
| 21 ><BODY | |
| 22 CLASS="REFENTRY" | |
| 23 BGCOLOR="#FFF8DC" | |
| 24 TEXT="#000000" | |
| 25 LINK="#0000ee" | |
| 26 VLINK="#551a8b" | |
| 27 ALINK="#ff0000" | |
| 28 ><DIV | |
| 29 CLASS="NAVHEADER" | |
| 30 ><TABLE | |
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31 SUMMARY="Header navigation table" |
| 0 | 32 WIDTH="100%" |
| 33 BORDER="0" | |
| 34 CELLPADDING="0" | |
| 35 CELLSPACING="0" | |
| 36 ><TR | |
| 37 ><TH | |
| 38 COLSPAN="3" | |
| 39 ALIGN="center" | |
| 40 >SDL Library Documentation</TH | |
| 41 ></TR | |
| 42 ><TR | |
| 43 ><TD | |
| 44 WIDTH="10%" | |
| 45 ALIGN="left" | |
| 46 VALIGN="bottom" | |
| 47 ><A | |
| 48 HREF="sdljoystickupdate.html" | |
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49 ACCESSKEY="P" |
| 0 | 50 >Prev</A |
| 51 ></TD | |
| 52 ><TD | |
| 53 WIDTH="80%" | |
| 54 ALIGN="center" | |
| 55 VALIGN="bottom" | |
| 56 ></TD | |
| 57 ><TD | |
| 58 WIDTH="10%" | |
| 59 ALIGN="right" | |
| 60 VALIGN="bottom" | |
| 61 ><A | |
| 62 HREF="sdljoystickgethat.html" | |
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63 ACCESSKEY="N" |
| 0 | 64 >Next</A |
| 65 ></TD | |
| 66 ></TR | |
| 67 ></TABLE | |
| 68 ><HR | |
| 69 ALIGN="LEFT" | |
| 70 WIDTH="100%"></DIV | |
| 71 ><H1 | |
| 72 ><A | |
| 73 NAME="SDLJOYSTICKGETAXIS" | |
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74 ></A |
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75 >SDL_JoystickGetAxis</H1 |
| 0 | 76 ><DIV |
| 77 CLASS="REFNAMEDIV" | |
| 78 ><A | |
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79 NAME="AEN6320" |
| 0 | 80 ></A |
| 81 ><H2 | |
| 82 >Name</H2 | |
| 83 >SDL_JoystickGetAxis -- Get the current state of an axis</DIV | |
| 84 ><DIV | |
| 85 CLASS="REFSYNOPSISDIV" | |
| 86 ><A | |
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87 NAME="AEN6323" |
| 0 | 88 ></A |
| 89 ><H2 | |
| 90 >Synopsis</H2 | |
| 91 ><DIV | |
| 92 CLASS="FUNCSYNOPSIS" | |
| 93 ><A | |
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94 NAME="AEN6324" |
| 0 | 95 ></A |
| 96 ><P | |
| 97 ></P | |
| 98 ><PRE | |
| 99 CLASS="FUNCSYNOPSISINFO" | |
| 100 >#include "SDL.h"</PRE | |
| 101 ><P | |
| 102 ><CODE | |
| 103 ><CODE | |
| 104 CLASS="FUNCDEF" | |
| 105 >Sint16 <B | |
| 106 CLASS="FSFUNC" | |
| 107 >SDL_JoystickGetAxis</B | |
| 108 ></CODE | |
| 109 >(SDL_Joystick *joystick, int axis);</CODE | |
| 110 ></P | |
| 111 ><P | |
| 112 ></P | |
| 113 ></DIV | |
| 114 ></DIV | |
| 115 ><DIV | |
| 116 CLASS="REFSECT1" | |
| 117 ><A | |
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118 NAME="AEN6330" |
| 0 | 119 ></A |
| 120 ><H2 | |
| 121 >Description</H2 | |
| 122 ><P | |
| 123 ><TT | |
| 124 CLASS="FUNCTION" | |
| 125 >SDL_JoystickGetAxis</TT | |
| 126 > returns the current state of the given <TT | |
| 127 CLASS="PARAMETER" | |
| 128 ><I | |
| 129 >axis</I | |
| 130 ></TT | |
| 131 > on the given <TT | |
| 132 CLASS="PARAMETER" | |
| 133 ><I | |
| 134 >joystick</I | |
| 135 ></TT | |
| 136 >.</P | |
| 137 ><P | |
| 138 >On most modern joysticks the X axis is usually represented by <TT | |
| 139 CLASS="PARAMETER" | |
| 140 ><I | |
| 141 >axis</I | |
| 142 ></TT | |
| 143 > 0 and the Y axis by <TT | |
| 144 CLASS="PARAMETER" | |
| 145 ><I | |
| 146 >axis</I | |
| 147 ></TT | |
| 148 > 1. The value returned by <TT | |
| 149 CLASS="FUNCTION" | |
| 150 >SDL_JoystickGetAxis</TT | |
| 151 > is a signed integer (-32768 to 32768) representing the current position of the <TT | |
| 152 CLASS="PARAMETER" | |
| 153 ><I | |
| 154 >axis</I | |
| 155 ></TT | |
| 156 >, 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.</P | |
| 157 ></DIV | |
| 158 ><DIV | |
| 159 CLASS="REFSECT1" | |
| 160 ><A | |
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161 NAME="AEN6341" |
| 0 | 162 ></A |
| 163 ><H2 | |
| 164 >Return Value</H2 | |
| 165 ><P | |
| 166 >Returns a 16-bit signed integer representing the current position of the <TT | |
| 167 CLASS="PARAMETER" | |
| 168 ><I | |
| 169 >axis</I | |
| 170 ></TT | |
| 171 >.</P | |
| 172 ></DIV | |
| 173 ><DIV | |
| 174 CLASS="REFSECT1" | |
| 175 ><A | |
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176 NAME="AEN6345" |
| 0 | 177 ></A |
| 178 ><H2 | |
| 179 >Examples</H2 | |
| 180 ><P | |
| 181 ><PRE | |
| 182 CLASS="PROGRAMLISTING" | |
| 183 >Sint16 x_move, y_move; | |
| 184 SDL_Joystick *joy1; | |
| 185 . | |
| 186 . | |
| 187 x_move=SDL_JoystickGetAxis(joy1, 0); | |
| 188 y_move=SDL_JoystickGetAxis(joy1, 1);</PRE | |
| 189 ></P | |
| 190 ></DIV | |
| 191 ><DIV | |
| 192 CLASS="REFSECT1" | |
| 193 ><A | |
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194 NAME="AEN6349" |
| 0 | 195 ></A |
| 196 ><H2 | |
| 197 >See Also</H2 | |
| 198 ><P | |
| 199 ><A | |
| 200 HREF="sdljoysticknumaxes.html" | |
| 201 ><TT | |
| 202 CLASS="FUNCTION" | |
| 203 >SDL_JoystickNumAxes</TT | |
| 204 ></A | |
| 205 ></P | |
| 206 ></DIV | |
| 207 ><DIV | |
| 208 CLASS="NAVFOOTER" | |
| 209 ><HR | |
| 210 ALIGN="LEFT" | |
| 211 WIDTH="100%"><TABLE | |
|
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212 SUMMARY="Footer navigation table" |
| 0 | 213 WIDTH="100%" |
| 214 BORDER="0" | |
| 215 CELLPADDING="0" | |
| 216 CELLSPACING="0" | |
| 217 ><TR | |
| 218 ><TD | |
| 219 WIDTH="33%" | |
| 220 ALIGN="left" | |
| 221 VALIGN="top" | |
| 222 ><A | |
| 223 HREF="sdljoystickupdate.html" | |
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224 ACCESSKEY="P" |
| 0 | 225 >Prev</A |
| 226 ></TD | |
| 227 ><TD | |
| 228 WIDTH="34%" | |
| 229 ALIGN="center" | |
| 230 VALIGN="top" | |
| 231 ><A | |
| 232 HREF="index.html" | |
|
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233 ACCESSKEY="H" |
| 0 | 234 >Home</A |
| 235 ></TD | |
| 236 ><TD | |
| 237 WIDTH="33%" | |
| 238 ALIGN="right" | |
| 239 VALIGN="top" | |
| 240 ><A | |
| 241 HREF="sdljoystickgethat.html" | |
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242 ACCESSKEY="N" |
| 0 | 243 >Next</A |
| 244 ></TD | |
| 245 ></TR | |
| 246 ><TR | |
| 247 ><TD | |
| 248 WIDTH="33%" | |
| 249 ALIGN="left" | |
| 250 VALIGN="top" | |
| 251 >SDL_JoystickUpdate</TD | |
| 252 ><TD | |
| 253 WIDTH="34%" | |
| 254 ALIGN="center" | |
| 255 VALIGN="top" | |
| 256 ><A | |
| 257 HREF="joystick.html" | |
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258 ACCESSKEY="U" |
| 0 | 259 >Up</A |
| 260 ></TD | |
| 261 ><TD | |
| 262 WIDTH="33%" | |
| 263 ALIGN="right" | |
| 264 VALIGN="top" | |
| 265 >SDL_JoystickGetHat</TD | |
| 266 ></TR | |
| 267 ></TABLE | |
| 268 ></DIV | |
| 269 ></BODY | |
| 270 ></HTML | |
| 271 > |