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annotate docs/html/guidetimeexamples.html @ 1157:baf35853ad54
Date: Mon, 10 Oct 2005 13:09:32 +0300
From: Tommi Kyntola <tommi.kyntola@ray.fi>
To: sdl@libsdl.org
Subject: [SDL] [RFC] get_ticks broken on linux
It uses gettimeofday to calculate the timedifference.
Gettimeofday returns current time which is seldom monotonous.
This breaks SDL timer subsystem. (time callbacks and all that
get borked when the time difference ms is suddenly ~ 2^32)
I posted a message about this earlier but got no response.
Some thoughts on this matter would be appreciated.
(Or even an explanation for the lack of interest.)
A patch below would use the posix timers that have been around
since posix 93 and do provide a good source of monotonous time
on linux boxes (and on few others too).
The following patch is also availabe at:
http://www.hut.fi/u/tkyntola/SDL-1.2.9-clockfix.patch
It's against 1.2.9, but I can easily rediffit against
the cvs branch is needed.
cheers,
Tommi Kyntola tommi.kyntola@ray.fi
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Tue, 11 Oct 2005 18:16:12 +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 | |
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108 /* main game loop */ |
0 | 109 |
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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 > |