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view docs/html/sdljoystickgetball.html @ 3958:85b6fb6a5e3c SDL-1.2

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Actually, this is a better fix...clear the error state once if everything we need loaded; it's more efficient, and works even if the last unnecessary xrandr symbol failed to load. Otherwise, leave the original loadso error, so the end user can find out what symbol failed.
author Ryan C. Gordon <icculus@icculus.org>
date Wed, 13 Jun 2007 08:00:10 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_JoystickGetBall</TITLE
><META
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
"><LINK
REL="HOME"
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><HR
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><H1
><A
NAME="SDLJOYSTICKGETBALL"
></A
>SDL_JoystickGetBall</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN6433"
></A
><H2
>Name</H2
>SDL_JoystickGetBall&nbsp;--&nbsp;Get relative trackball motion</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN6436"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN6437"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_JoystickGetBall</B
></CODE
>(SDL_Joystick *joystick, int ball, int *dx, int *dy);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6443"
></A
><H2
>Description</H2
><P
>Get the <TT
CLASS="PARAMETER"
><I
>ball</I
></TT
> axis change.</P
><P
>Trackballs can only return relative motion since the last call to <TT
CLASS="FUNCTION"
>SDL_JoystickGetBall</TT
>, these motion deltas a placed into <TT
CLASS="PARAMETER"
><I
>dx</I
></TT
> and <TT
CLASS="PARAMETER"
><I
>dy</I
></TT
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6451"
></A
><H2
>Return Value</H2
><P
>Returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> on success or <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> on failure</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6456"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>int delta_x, delta_y;
SDL_Joystick *joy;
.
.
.
SDL_JoystickUpdate();
if(SDL_JoystickGetBall(joy, 0, &#38;delta_x, &#38;delta_y)==-1)
  printf("TrackBall Read Error!\n");
printf("Trackball Delta- X:%d, Y:%d\n", delta_x, delta_y);</PRE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6460"
></A
><H2
>See Also</H2
><P
><A
HREF="sdljoysticknumballs.html"
><TT
CLASS="FUNCTION"
>SDL_JoystickNumBalls</TT
></A
></P
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