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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 355632dca928
children
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<HTML
><HEAD
><TITLE
>Joystick</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
"><LINK
REL="HOME"
TITLE="SDL Library Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="SDL Reference"
HREF="reference.html"><LINK
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TITLE="SDL_JoystickEventState"
HREF="sdljoystickeventstate.html"><LINK
REL="NEXT"
TITLE="SDL_NumJoysticks"
HREF="sdlnumjoysticks.html"><META
NAME="KEYWORD"
CONTENT="joystick"><META
NAME="KEYWORD"
CONTENT="function"></HEAD
><BODY
CLASS="CHAPTER"
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><HR
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><DIV
CLASS="CHAPTER"
><H1
><A
NAME="JOYSTICK"
></A
>Chapter 9. Joystick</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="sdlnumjoysticks.html"
>SDL_NumJoysticks</A
>&nbsp;--&nbsp;Count available joysticks.</DT
><DT
><A
HREF="sdljoystickname.html"
>SDL_JoystickName</A
>&nbsp;--&nbsp;Get joystick name.</DT
><DT
><A
HREF="sdljoystickopen.html"
>SDL_JoystickOpen</A
>&nbsp;--&nbsp;Opens a joystick for use.</DT
><DT
><A
HREF="sdljoystickopened.html"
>SDL_JoystickOpened</A
>&nbsp;--&nbsp;Determine if a joystick has been opened</DT
><DT
><A
HREF="sdljoystickindex.html"
>SDL_JoystickIndex</A
>&nbsp;--&nbsp;Get the index of an SDL_Joystick.</DT
><DT
><A
HREF="sdljoysticknumaxes.html"
>SDL_JoystickNumAxes</A
>&nbsp;--&nbsp;Get the number of joystick axes</DT
><DT
><A
HREF="sdljoysticknumballs.html"
>SDL_JoystickNumBalls</A
>&nbsp;--&nbsp;Get the number of joystick trackballs</DT
><DT
><A
HREF="sdljoysticknumhats.html"
>SDL_JoystickNumHats</A
>&nbsp;--&nbsp;Get the number of joystick hats</DT
><DT
><A
HREF="sdljoysticknumbuttons.html"
>SDL_JoystickNumButtons</A
>&nbsp;--&nbsp;Get the number of joysitck buttons</DT
><DT
><A
HREF="sdljoystickupdate.html"
>SDL_JoystickUpdate</A
>&nbsp;--&nbsp;Updates the state of all joysticks</DT
><DT
><A
HREF="sdljoystickgetaxis.html"
>SDL_JoystickGetAxis</A
>&nbsp;--&nbsp;Get the current state of an axis</DT
><DT
><A
HREF="sdljoystickgethat.html"
>SDL_JoystickGetHat</A
>&nbsp;--&nbsp;Get the current state of a joystick hat</DT
><DT
><A
HREF="sdljoystickgetbutton.html"
>SDL_JoystickGetButton</A
>&nbsp;--&nbsp;Get the current state of a given button on a given joystick</DT
><DT
><A
HREF="sdljoystickgetball.html"
>SDL_JoystickGetBall</A
>&nbsp;--&nbsp;Get relative trackball motion</DT
><DT
><A
HREF="sdljoystickclose.html"
>SDL_JoystickClose</A
>&nbsp;--&nbsp;Closes a previously opened joystick</DT
></DL
></DIV
><P
>Joysticks, and other similar input devices, have a very strong role in game playing and SDL provides comprehensive support for them. Axes, Buttons, POV Hats and trackballs are all supported.</P
><P
>Joystick support is initialized by passed the <TT
CLASS="LITERAL"
>SDL_INIT_JOYSTICK</TT
> flag to <A
HREF="sdlinit.html"
><TT
CLASS="FUNCTION"
>SDL_Init</TT
></A
>. Once initilized joysticks must be opened using <A
HREF="sdljoystickopen.html"
><TT
CLASS="FUNCTION"
>SDL_JoystickOpen</TT
></A
>.</P
><P
>While using the functions describe in this secton may seem like the best way to access and read from joysticks, in most cases they aren't. Ideally joysticks should be read using the <A
HREF="event.html"
>event</A
> system. To enable this, you must set the joystick event processing state with <A
HREF="sdljoystickeventstate.html"
><TT
CLASS="FUNCTION"
>SDL_JoystickEventState</TT
></A
>. Joysticks must be <A
HREF="sdljoystickopen.html"
>opened</A
> before they can be used of course.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>If you are <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not</I
></SPAN
> handling the joystick via the event queue then you must explicitly request a joystick update by calling <A
HREF="sdljoystickupdate.html"
><TT
CLASS="FUNCTION"
>SDL_JoystickUpdate</TT
></A
>.</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>Force Feedback is not yet support. Sam (slouken@libsdl.org) is soliciting suggestions from people with force-feedback experience on the best wat to desgin the API.</P
></BLOCKQUOTE
></DIV
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