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annotate docs/html/guidetimeexamples.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 |
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0 | 1 <HTML |
2 ><HEAD | |
3 ><TITLE | |
4 >Time Examples</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="Examples" | |
14 HREF="guideexamples.html"><LINK | |
15 REL="PREVIOUS" | |
16 TITLE="CDROM Examples" | |
17 HREF="guidecdromexamples.html"><LINK | |
18 REL="NEXT" | |
19 TITLE="SDL Reference" | |
20 HREF="reference.html"></HEAD | |
21 ><BODY | |
22 CLASS="SECT1" | |
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="guidecdromexamples.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 >Chapter 4. Examples</TD | |
57 ><TD | |
58 WIDTH="10%" | |
59 ALIGN="right" | |
60 VALIGN="bottom" | |
61 ><A | |
62 HREF="reference.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 ><DIV | |
72 CLASS="SECT1" | |
73 ><H1 | |
74 CLASS="SECT1" | |
75 ><A | |
76 NAME="GUIDETIMEEXAMPLES" | |
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77 ></A |
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78 >Time Examples</H1 |
0 | 79 ><P |
80 ></P | |
81 ><DIV | |
82 CLASS="SECT2" | |
83 ><H2 | |
84 CLASS="SECT2" | |
85 ><A | |
55
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86 NAME="AEN412" |
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87 ></A |
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88 >Time based game loop</H2 |
0 | 89 ><P |
90 ><PRE | |
91 CLASS="PROGRAMLISTING" | |
92 >#define TICK_INTERVAL 30 | |
93 | |
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94 static Uint32 next_time; |
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95 |
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96 Uint32 time_left(void) |
0 | 97 { |
98 Uint32 now; | |
99 | |
100 now = SDL_GetTicks(); | |
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101 if(next_time <= now) |
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102 return 0; |
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103 else |
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104 return next_time - now; |
0 | 105 } |
106 | |
107 | |
181
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108 /* main game loop */ |
0 | 109 |
181
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110 next_time = SDL_GetTicks() + TICK_INTERVAL; |
0 | 111 while ( game_running ) { |
181
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112 update_game_state(); |
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113 SDL_Delay(time_left()); |
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114 next_time += TICK_INTERVAL; |
0 | 115 } </PRE |
116 ></P | |
117 ></DIV | |
118 ></DIV | |
119 ><DIV | |
120 CLASS="NAVFOOTER" | |
121 ><HR | |
122 ALIGN="LEFT" | |
123 WIDTH="100%"><TABLE | |
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124 SUMMARY="Footer navigation table" |
0 | 125 WIDTH="100%" |
126 BORDER="0" | |
127 CELLPADDING="0" | |
128 CELLSPACING="0" | |
129 ><TR | |
130 ><TD | |
131 WIDTH="33%" | |
132 ALIGN="left" | |
133 VALIGN="top" | |
134 ><A | |
135 HREF="guidecdromexamples.html" | |
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136 ACCESSKEY="P" |
0 | 137 >Prev</A |
138 ></TD | |
139 ><TD | |
140 WIDTH="34%" | |
141 ALIGN="center" | |
142 VALIGN="top" | |
143 ><A | |
144 HREF="index.html" | |
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145 ACCESSKEY="H" |
0 | 146 >Home</A |
147 ></TD | |
148 ><TD | |
149 WIDTH="33%" | |
150 ALIGN="right" | |
151 VALIGN="top" | |
152 ><A | |
153 HREF="reference.html" | |
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154 ACCESSKEY="N" |
0 | 155 >Next</A |
156 ></TD | |
157 ></TR | |
158 ><TR | |
159 ><TD | |
160 WIDTH="33%" | |
161 ALIGN="left" | |
162 VALIGN="top" | |
163 >CDROM Examples</TD | |
164 ><TD | |
165 WIDTH="34%" | |
166 ALIGN="center" | |
167 VALIGN="top" | |
168 ><A | |
169 HREF="guideexamples.html" | |
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170 ACCESSKEY="U" |
0 | 171 >Up</A |
172 ></TD | |
173 ><TD | |
174 WIDTH="33%" | |
175 ALIGN="right" | |
176 VALIGN="top" | |
177 >SDL Reference</TD | |
178 ></TR | |
179 ></TABLE | |
180 ></DIV | |
181 ></BODY | |
182 ></HTML | |
183 > |