Mercurial > sdl-ios-xcode
annotate docs/html/sdljoystickgetball.html @ 968:4675910b0b7b
Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST)
From: Hannu Savolainen
Subject: Re: SDL uses obsolete OSS features
I did some work on getting OSS to work better with SDL. There have been
some problems with select which should be fixed now.
I'm having some problems in understanding what is the purpose of the
DSP_WaitAudio() routine. I added a return to the very beginning of this
routine and commendted out the define for USE_BLOCKING_WRITES. At least
lbreakout2 seems to work as well as earlier. The latencies are the same.
An ordinary blocking write does exactly the same thing than DSP_WaitAudio
does. So I would recommend using the USE_BLOCKING_WRITES approach and
removing everything from the DSP_WaitAudio routine. Also enabling
USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because
you don't need to handle the partial writes (the do-while loop).
Attached is a patch against SDL-1.2.7. After these changes SDL will use
OSS as it's designed to be used (make it as simple as possible). This code
should work with all OSS implementations because it uses only the very
fundamental features that have been there since the jurassic times.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Fri, 12 Nov 2004 21:39:04 +0000 |
parents | 355632dca928 |
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rev | line source |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >SDL_JoystickGetBall</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_JoystickGetButton" | |
17 HREF="sdljoystickgetbutton.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL_JoystickClose" | |
20 HREF="sdljoystickclose.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="sdljoystickgetbutton.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="sdljoystickclose.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="SDLJOYSTICKGETBALL" | |
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74 ></A |
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75 >SDL_JoystickGetBall</H1 |
0 | 76 ><DIV |
77 CLASS="REFNAMEDIV" | |
78 ><A | |
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79 NAME="AEN6433" |
0 | 80 ></A |
81 ><H2 | |
82 >Name</H2 | |
83 >SDL_JoystickGetBall -- Get relative trackball motion</DIV | |
84 ><DIV | |
85 CLASS="REFSYNOPSISDIV" | |
86 ><A | |
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87 NAME="AEN6436" |
0 | 88 ></A |
89 ><H2 | |
90 >Synopsis</H2 | |
91 ><DIV | |
92 CLASS="FUNCSYNOPSIS" | |
93 ><A | |
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94 NAME="AEN6437" |
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 >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 | |
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118 NAME="AEN6443" |
0 | 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 | |
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148 NAME="AEN6451" |
0 | 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 | |
161 ><DIV | |
162 CLASS="REFSECT1" | |
163 ><A | |
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164 NAME="AEN6456" |
0 | 165 ></A |
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, &delta_x, &delta_y)==-1) | |
178 printf("TrackBall Read Error!\n"); | |
179 printf("Trackball Delta- X:%d, Y:%d\n", delta_x, delta_y);</PRE | |
180 ></P | |
181 ></DIV | |
182 ><DIV | |
183 CLASS="REFSECT1" | |
184 ><A | |
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185 NAME="AEN6460" |
0 | 186 ></A |
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 | |
196 ></P | |
197 ></DIV | |
198 ><DIV | |
199 CLASS="NAVFOOTER" | |
200 ><HR | |
201 ALIGN="LEFT" | |
202 WIDTH="100%"><TABLE | |
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203 SUMMARY="Footer navigation table" |
0 | 204 WIDTH="100%" |
205 BORDER="0" | |
206 CELLPADDING="0" | |
207 CELLSPACING="0" | |
208 ><TR | |
209 ><TD | |
210 WIDTH="33%" | |
211 ALIGN="left" | |
212 VALIGN="top" | |
213 ><A | |
214 HREF="sdljoystickgetbutton.html" | |
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215 ACCESSKEY="P" |
0 | 216 >Prev</A |
217 ></TD | |
218 ><TD | |
219 WIDTH="34%" | |
220 ALIGN="center" | |
221 VALIGN="top" | |
222 ><A | |
223 HREF="index.html" | |
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224 ACCESSKEY="H" |
0 | 225 >Home</A |
226 ></TD | |
227 ><TD | |
228 WIDTH="33%" | |
229 ALIGN="right" | |
230 VALIGN="top" | |
231 ><A | |
232 HREF="sdljoystickclose.html" | |
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233 ACCESSKEY="N" |
0 | 234 >Next</A |
235 ></TD | |
236 ></TR | |
237 ><TR | |
238 ><TD | |
239 WIDTH="33%" | |
240 ALIGN="left" | |
241 VALIGN="top" | |
242 >SDL_JoystickGetButton</TD | |
243 ><TD | |
244 WIDTH="34%" | |
245 ALIGN="center" | |
246 VALIGN="top" | |
247 ><A | |
248 HREF="joystick.html" | |
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249 ACCESSKEY="U" |
0 | 250 >Up</A |
251 ></TD | |
252 ><TD | |
253 WIDTH="33%" | |
254 ALIGN="right" | |
255 VALIGN="top" | |
256 >SDL_JoystickClose</TD | |
257 ></TR | |
258 ></TABLE | |
259 ></DIV | |
260 ></BODY | |
261 ></HTML | |
262 > |