Mercurial > sdl-ios-xcode
annotate docs/html/guidebasicsinit.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> |
|---|---|
| date | Tue, 11 Oct 2005 18:16:12 +0000 |
| parents | 355632dca928 |
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| rev | line source |
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| 0 | 1 <HTML |
| 2 ><HEAD | |
| 3 ><TITLE | |
| 4 >Initializing SDL</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="The Basics" | |
| 14 HREF="guidethebasics.html"><LINK | |
| 15 REL="PREVIOUS" | |
| 16 TITLE="The Basics" | |
| 17 HREF="guidethebasics.html"><LINK | |
| 18 REL="NEXT" | |
| 19 TITLE="Graphics and Video" | |
| 20 HREF="guidevideo.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="guidethebasics.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 1. The Basics</TD | |
| 57 ><TD | |
| 58 WIDTH="10%" | |
| 59 ALIGN="right" | |
| 60 VALIGN="bottom" | |
| 61 ><A | |
| 62 HREF="guidevideo.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="GUIDEBASICSINIT" | |
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77 ></A |
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78 >Initializing SDL</H1 |
| 0 | 79 ><P |
| 80 >SDL is composed of eight subsystems - Audio, CDROM, Event Handling, File I/O, Joystick Handling, Threading, Timers and Video. Before you can use any of these subsystems they must be initialized by calling <A | |
| 81 HREF="sdlinit.html" | |
| 82 ><TT | |
| 83 CLASS="FUNCTION" | |
| 84 >SDL_Init</TT | |
| 85 ></A | |
| 86 > (or <A | |
| 87 HREF="sdlinitsubsystem.html" | |
| 88 ><TT | |
| 89 CLASS="FUNCTION" | |
| 90 >SDL_InitSubSystem</TT | |
| 91 ></A | |
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92 >). <TT |
| 0 | 93 CLASS="FUNCTION" |
| 94 >SDL_Init</TT | |
| 95 > must be called before any other SDL function. It automatically initializes the Event Handling, File I/O and Threading subsystems and it takes a parameter specifying which other subsystems to initialize. So, to initialize the default subsystems and the Video subsystems you would call: | |
| 96 <PRE | |
| 97 CLASS="PROGRAMLISTING" | |
| 98 > SDL_Init ( SDL_INIT_VIDEO );</PRE | |
| 99 > | |
| 100 To initialize the default subsystems, the Video subsystem and the Timers subsystem you would call: | |
| 101 <PRE | |
| 102 CLASS="PROGRAMLISTING" | |
| 103 > SDL_Init ( SDL_INIT_VIDEO | SDL_INIT_TIMER );</PRE | |
| 104 ></P | |
| 105 ><P | |
| 106 ><TT | |
| 107 CLASS="FUNCTION" | |
| 108 >SDL_Init</TT | |
| 109 > is complemented by <A | |
| 110 HREF="sdlquit.html" | |
| 111 ><TT | |
| 112 CLASS="FUNCTION" | |
| 113 >SDL_Quit</TT | |
| 114 ></A | |
| 115 > (and <A | |
| 116 HREF="sdlquitsubsystem.html" | |
| 117 ><TT | |
| 118 CLASS="FUNCTION" | |
| 119 >SDL_QuitSubSystem</TT | |
| 120 ></A | |
| 121 >). <TT | |
| 122 CLASS="FUNCTION" | |
| 123 >SDL_Quit</TT | |
| 124 > shuts down all subsystems, including the default ones. It should always be called before a SDL application exits.</P | |
| 125 ><P | |
| 126 >With <TT | |
| 127 CLASS="FUNCTION" | |
| 128 >SDL_Init</TT | |
| 129 > and <TT | |
| 130 CLASS="FUNCTION" | |
| 131 >SDL_Quit</TT | |
| 132 > firmly embedded in your programmers toolkit you can write your first and most basic SDL application. However, we must be prepare to handle errors. Many SDL functions return a value and indicates whether the function has succeeded or failed, <TT | |
| 133 CLASS="FUNCTION" | |
| 134 >SDL_Init</TT | |
| 135 >, for instance, returns -1 if it could not initialize a subsystem. SDL provides a useful facility that allows you to determine exactly what the problem was, every time an error occurs within SDL an error message is stored which can be retrieved using <TT | |
| 136 CLASS="FUNCTION" | |
| 137 >SDL_GetError</TT | |
| 138 >. Use this often, you can never know too much about an error.</P | |
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139 ><DIV |
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140 CLASS="EXAMPLE" |
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141 ><A |
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142 NAME="AEN60" |
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143 ></A |
| 0 | 144 ><P |
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145 ><B |
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146 >Example 1-1. Initializing SDL</B |
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147 ></P |
| 0 | 148 ><PRE |
| 149 CLASS="PROGRAMLISTING" | |
| 150 >#include "SDL.h" /* All SDL App's need this */ | |
| 151 #include <stdio.h> | |
| 152 | |
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153 int main(int argc, char *argv[]) { |
| 0 | 154 |
| 155 printf("Initializing SDL.\n"); | |
| 156 | |
| 157 /* Initialize defaults, Video and Audio */ | |
| 158 if((SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO)==-1)) { | |
| 159 printf("Could not initialize SDL: %s.\n", SDL_GetError()); | |
| 160 exit(-1); | |
| 161 } | |
| 162 | |
| 163 printf("SDL initialized.\n"); | |
| 164 | |
| 165 printf("Quiting SDL.\n"); | |
| 166 | |
| 167 /* Shutdown all subsystems */ | |
| 168 SDL_Quit(); | |
| 169 | |
| 170 printf("Quiting....\n"); | |
| 171 | |
| 172 exit(0); | |
| 173 } </PRE | |
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174 ></DIV |
| 0 | 175 ></DIV |
| 176 ><DIV | |
| 177 CLASS="NAVFOOTER" | |
| 178 ><HR | |
| 179 ALIGN="LEFT" | |
| 180 WIDTH="100%"><TABLE | |
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181 SUMMARY="Footer navigation table" |
| 0 | 182 WIDTH="100%" |
| 183 BORDER="0" | |
| 184 CELLPADDING="0" | |
| 185 CELLSPACING="0" | |
| 186 ><TR | |
| 187 ><TD | |
| 188 WIDTH="33%" | |
| 189 ALIGN="left" | |
| 190 VALIGN="top" | |
| 191 ><A | |
| 192 HREF="guidethebasics.html" | |
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193 ACCESSKEY="P" |
| 0 | 194 >Prev</A |
| 195 ></TD | |
| 196 ><TD | |
| 197 WIDTH="34%" | |
| 198 ALIGN="center" | |
| 199 VALIGN="top" | |
| 200 ><A | |
| 201 HREF="index.html" | |
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202 ACCESSKEY="H" |
| 0 | 203 >Home</A |
| 204 ></TD | |
| 205 ><TD | |
| 206 WIDTH="33%" | |
| 207 ALIGN="right" | |
| 208 VALIGN="top" | |
| 209 ><A | |
| 210 HREF="guidevideo.html" | |
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211 ACCESSKEY="N" |
| 0 | 212 >Next</A |
| 213 ></TD | |
| 214 ></TR | |
| 215 ><TR | |
| 216 ><TD | |
| 217 WIDTH="33%" | |
| 218 ALIGN="left" | |
| 219 VALIGN="top" | |
| 220 >The Basics</TD | |
| 221 ><TD | |
| 222 WIDTH="34%" | |
| 223 ALIGN="center" | |
| 224 VALIGN="top" | |
| 225 ><A | |
| 226 HREF="guidethebasics.html" | |
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227 ACCESSKEY="U" |
| 0 | 228 >Up</A |
| 229 ></TD | |
| 230 ><TD | |
| 231 WIDTH="33%" | |
| 232 ALIGN="right" | |
| 233 VALIGN="top" | |
| 234 >Graphics and Video</TD | |
| 235 ></TR | |
| 236 ></TABLE | |
| 237 ></DIV | |
| 238 ></BODY | |
| 239 ></HTML | |
| 240 > |