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4>SDL_JoystickGetBall</TITLE
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71><H1
72><A
73NAME="SDLJOYSTICKGETBALL"
74></A
75>SDL_JoystickGetBall</H1
76><DIV
77CLASS="REFNAMEDIV"
78><A
79NAME="AEN6433"
80></A
81><H2
82>Name</H2
83>SDL_JoystickGetBall&nbsp;--&nbsp;Get relative trackball motion</DIV
84><DIV
85CLASS="REFSYNOPSISDIV"
86><A
87NAME="AEN6436"
88></A
89><H2
90>Synopsis</H2
91><DIV
92CLASS="FUNCSYNOPSIS"
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94NAME="AEN6437"
95></A
96><P
97></P
98><PRE
99CLASS="FUNCSYNOPSISINFO"
100>#include "SDL.h"</PRE
101><P
102><CODE
103><CODE
104CLASS="FUNCDEF"
105>int <B
106CLASS="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
116CLASS="REFSECT1"
117><A
118NAME="AEN6443"
119></A
120><H2
121>Description</H2
122><P
123>Get the <TT
124CLASS="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
131CLASS="FUNCTION"
132>SDL_JoystickGetBall</TT
133>, these motion deltas a placed into <TT
134CLASS="PARAMETER"
135><I
136>dx</I
137></TT
138> and <TT
139CLASS="PARAMETER"
140><I
141>dy</I
142></TT
143>.</P
144></DIV
145><DIV
146CLASS="REFSECT1"
147><A
148NAME="AEN6451"
149></A
150><H2
151>Return Value</H2
152><P
153>Returns <SPAN
154CLASS="RETURNVALUE"
155>0</SPAN
156> on success or <SPAN
157CLASS="RETURNVALUE"
158>-1</SPAN
159> on failure</P
160></DIV
161><DIV
162CLASS="REFSECT1"
163><A
164NAME="AEN6456"
165></A
166><H2
167>Examples</H2
168><P
169><PRE
170CLASS="PROGRAMLISTING"
171>int delta_x, delta_y;
172SDL_Joystick *joy;
173.
174.
175.
176SDL_JoystickUpdate();
177if(SDL_JoystickGetBall(joy, 0, &#38;delta_x, &#38;delta_y)==-1)
178  printf("TrackBall Read Error!\n");
179printf("Trackball Delta- X:%d, Y:%d\n", delta_x, delta_y);</PRE
180></P
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183CLASS="REFSECT1"
184><A
185NAME="AEN6460"
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187><H2
188>See Also</H2
189><P
190><A
191HREF="sdljoysticknumballs.html"
192><TT
193CLASS="FUNCTION"
194>SDL_JoystickNumBalls</TT
195></A
196></P
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