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     75 >SDL_JoystickGetBall</H1
     76 ><DIV
     77 CLASS="REFNAMEDIV"
     78 ><A
     79 NAME="AEN6433"
     80 ></A
     81 ><H2
     82 >Name</H2
     83 >SDL_JoystickGetBall&nbsp;--&nbsp;Get relative trackball motion</DIV
     84 ><DIV
     85 CLASS="REFSYNOPSISDIV"
     86 ><A
     87 NAME="AEN6436"
     88 ></A
     89 ><H2
     90 >Synopsis</H2
     91 ><DIV
     92 CLASS="FUNCSYNOPSIS"
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     94 NAME="AEN6437"
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     96 ><P
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     98 ><PRE
     99 CLASS="FUNCSYNOPSISINFO"
    100 >#include "SDL.h"</PRE
    101 ><P
    102 ><CODE
    103 ><CODE
    104 CLASS="FUNCDEF"
    105 >int <B
    106 CLASS="FSFUNC"
    107 >SDL_JoystickGetBall</B
    108 ></CODE
    109 >(SDL_Joystick *joystick, int ball, int *dx, int *dy);</CODE
    110 ></P
    111 ><P
    112 ></P
    113 ></DIV
    114 ></DIV
    115 ><DIV
    116 CLASS="REFSECT1"
    117 ><A
    118 NAME="AEN6443"
    119 ></A
    120 ><H2
    121 >Description</H2
    122 ><P
    123 >Get the <TT
    124 CLASS="PARAMETER"
    125 ><I
    126 >ball</I
    127 ></TT
    128 > axis change.</P
    129 ><P
    130 >Trackballs can only return relative motion since the last call to <TT
    131 CLASS="FUNCTION"
    132 >SDL_JoystickGetBall</TT
    133 >, these motion deltas a placed into <TT
    134 CLASS="PARAMETER"
    135 ><I
    136 >dx</I
    137 ></TT
    138 > and <TT
    139 CLASS="PARAMETER"
    140 ><I
    141 >dy</I
    142 ></TT
    143 >.</P
    144 ></DIV
    145 ><DIV
    146 CLASS="REFSECT1"
    147 ><A
    148 NAME="AEN6451"
    149 ></A
    150 ><H2
    151 >Return Value</H2
    152 ><P
    153 >Returns <SPAN
    154 CLASS="RETURNVALUE"
    155 >0</SPAN
    156 > on success or <SPAN
    157 CLASS="RETURNVALUE"
    158 >-1</SPAN
    159 > on failure</P
    160 ></DIV
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    164 NAME="AEN6456"
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    166 ><H2
    167 >Examples</H2
    168 ><P
    169 ><PRE
    170 CLASS="PROGRAMLISTING"
    171 >int delta_x, delta_y;
    172 SDL_Joystick *joy;
    173 .
    174 .
    175 .
    176 SDL_JoystickUpdate();
    177 if(SDL_JoystickGetBall(joy, 0, &#38;delta_x, &#38;delta_y)==-1)
    178   printf("TrackBall Read Error!\n");
    179 printf("Trackball Delta- X:%d, Y:%d\n", delta_x, delta_y);</PRE
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    183 CLASS="REFSECT1"
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    185 NAME="AEN6460"
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    187 ><H2
    188 >See Also</H2
    189 ><P
    190 ><A
    191 HREF="sdljoysticknumballs.html"
    192 ><TT
    193 CLASS="FUNCTION"
    194 >SDL_JoystickNumBalls</TT
    195 ></A
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