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te: Thu, 17 Apr 2003 11:25:26 -0700 From: "Jim" Subject: [SDL] Frame buffer patches... Would seem that GCC 3.2.2 promotes all signed values to unsigned if any single vlaue is unsigned in an expression... for instance when calculating an elo touch position....evertyhign is an (int) except for cach_vinfo.xres which is unsigned. THerefore if y ou reverse the SDL_ELO_MIN_X and SDL_ELO_MAX_X values the resulging negative value pegs the expression to it's max. Attached it the accumu lated patch to typecast the unsigned values to (int) - *dx = (cache_vinfo.xres - (cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); + *dx = ((int)cache_vinfo.xres - ((int)cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); and also to provide quite failure to operations which have the screen currently locked... The touch screen I'm using the original values were exactly opposite of any position I touched on the screen - evaluating the math the expr ession SHOULD have handled reversing the min and max values - and after casting the unsigned .xres and .yres to a signed int - worked well. .. Jim
author Sam Lantinga <slouken@libsdl.org>
date Tue, 24 Jan 2006 06:36:43 +0000
parents 74212992fb08
children 14717b52abc0
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<HTML
><HEAD
><TITLE
>Introduction</TITLE
>
</HEAD
><BODY
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TEXT="#000000"
LINK="#0000ee"
VLINK="#551a8b"
ALINK="#ff0000"
><DIV
CLASS="NAVHEADER"
>
<HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="PREFACE"
><H1
><A
NAME="AEN8"
>Introduction</A
></H1
><P
>This library is designed to make it easy to write games that run on Linux,
Win32 and BeOS using the various native high-performance media interfaces,
(for video, audio, etc) and presenting a single source-code level API to
your application.  This is a fairly low level API, but using this, completely
portable applications can be written with a great deal of flexibility.</P
><P
>The library is loaded as a dynamically linked library on its native
platform, and is currently compiled natively for Linux, compiled for
Win32 using a Linux hosted GCC
<A
HREF="http://www.libsdl.org/Xmingw32/"
TARGET="_top"
>cross-compilation</A
>
environment, and compiled using the EGCS C++ compiler under BeOS.</P
><P
>An introduction to SDL can be found online at:
<A
HREF="http://www.libsdl.org/intro/toc.html"
TARGET="_top"
>http://www.libsdl.org/intro/</A
>&#13;</P
><P
>There are code examples on each of the main library pages, and there are
fully fleshed example C++ classes and programs in the examples archive,
available on the
<A
HREF="http://www.libsdl.org/download.html"
TARGET="_top"
>SDL download page</A
>.</P
><P
>For an introduction to basic multi-media programming concepts, you might try
some of the following links:
<P
></P
><UL
><LI
><P
><A
HREF="http://www.ziron.com/links/"
TARGET="_top"
>Game Programming Links</A
></P
></LI
><LI
><P
><A
HREF="http://developer.dungeon-crawl.com/"
TARGET="_top"
>Game Developer Search Engine</A
></P
></LI
></UL
></P
><P
>Enjoy!</P
><P
>&nbsp;&nbsp;&nbsp; Sam Lantinga
<TT
CLASS="EMAIL"
>&#60;<A
HREF="mailto:slouken@libsdl.org"
><A
HREF="mailto:slouken@libsdl.org"
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>slouken@libsdl.org</A
></A
>&#62;</TT
></P
>
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<H1>Table of Contents</H1>
<UL>
<LI><A HREF="html/index.html">Full Table of Contents</A></LI>
<LI><A HREF="html/guide.html">The SDL Guide</A></LI>
<LI><A HREF="html/reference.html">The SDL Reference</A></LI>
<UL>
<LI><A HREF="html/general.html">Initialization</A></LI>
<LI><A HREF="html/video.html">Video</A></LI>
<LI><A HREF="html/wm.html">Window Manager</A></LI>
<LI><A HREF="html/event.html">Event Handling</A></LI>
<LI><A HREF="html/joystick.html">Joystick</A></LI>
<LI><A HREF="html/audio.html">Audio</A></LI>
<LI><A HREF="html/cdrom.html">CDROM</A></LI>
<LI><A HREF="html/thread.html">Threads</A></LI>
<LI><A HREF="html/time.html">Timers</A></LI>
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