README.Qtopia
author Sam Lantinga <slouken@libsdl.org>
Thu, 02 Apr 2009 04:43:36 +0000
branchSDL-1.2
changeset 4167 a6f635e5eaa6
parent 386 2c5d4c22a2ac
permissions -rw-r--r--
Fixed bug #611

From Tim Angus 2008-08-12 11:18:06

I'm one of the maintainers of ioquake3.org, an updated version of the
Quake 3 engine. Relatively recently, we moved ioq3 to use SDL as a
replacement for 95% of the platform specific code that was there. On the
whole it's doing a great job but unfortunately since the move we've been
getting complaints about the quality of the mouse input on the Windows
platform to the point where for many the game is unplayable. Put in
other terms, the current stable SDL 1.2 is basically not fit for purpose
if you need high quality mouse input as you do in a first person shooter.

Over the weekend I decided to pull my finger out and actually figure out
what's going on. There are basically two major problems. Firstly, when
using the "windib" driver, mouse input is gathered via the WM_MOUSEMOVE
message. Googling for this indicates that often this is known to result
in "spurious" and/or "missing" mouse movement events; this is the
primary cause of the poor mouse input. The second problem is that the
"directx" driver does not work at all in combination with OpenGL meaning
that you can't use DirectInput if your application also uses OpenGL. In
other words you're locked into using the "windib" driver and its poor
mouse input.

In order to address these problems I've done the following:

* Remove WM_MOUSEMOVE based motion event generation and replace with
calls to GetCursorPos which seems much more reliable. In order to
achieve this I've moved mouse motion out into a separate function that
is called once per DIB_PumpEvents.

* Remove the restriction on the "directx" driver being inoperable in
combination with OpenGL. There is a bug for this issues that I've
hijacked to a certain extent
(http://bugzilla.libsdl.org/show_bug.cgi?id=265). I'm the first to admit
I don't really understand why this restriction is there in the first
place. The commit message for the bug fix that introduced this
restriction (r581) isn't very elaborate and I couldn't see any other bug
tracking the issue. If anyone has more information on the bug that was
avoided by r581 it would be helpful as I/someone could then look into
addressing the problem without disabling the "directx" driver.

* I've also removed the restriction on not being allowed to use
DirectInput in windowed mode. I couldn't see any reason for this, at
least not from our perspective. I have my suspicions that it'll be
something like matching up the cursor with the mouse coordinates...

* I bumped up the DirectInput API used to version 7 in order to get
access to mouse buttons 4-7. I've had to inject a little bit of the DX7
headers into SDL there as the MinGW ones aren't up to date in this respect.
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==============================================================================
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Using the Simple DirectMedia Layer with Qtopia/OPIE
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==============================================================================
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==============================================================================
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I.  Setting up the Qtopia development environment.
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  This document will not explain how to setup the Qtopia development
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  environment. That is outside the scope of the document. You can read
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  more on this subject in this excellent howto:
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	http://www.zauruszone.com/howtos/linux_compiler_setup_howto.html
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==============================================================================
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II.  Building the Simple DirectMedia Layer libraries using the arm
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     cross-compiler
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  This is somewhat tricky since the name of the compiler binaries
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  differ from the standard. Also you should disable features not
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  needed. The command below works for me. Note that it's all one
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  line. You can also set the NM, LD etc environment variables
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  separately.
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	NM=arm-linux-nm LD=arm-linux-ld CC=arm-linux-gcc CXX=arm-linux-g++ RANLIB=arm-linux-ranlib AR=arm-linux-ar ./configure --enable-video-qtopia --disable-video-dummy --disable-video-fbcon  --disable-video-dga --disable-arts --disable-esd --disable-alsa --disable-cdrom --disable-video-x11 --disable-nasm --prefix=/opt/Qtopia/sharp/ arm-unknown-linux-gnu
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  One thing to note is that the above configure will include joystick
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  support, even though you can't have joysticks on the Zaurus. The
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  reason for this is to avoid link / compile / runtime errors with
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  applications that have joystick support.
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==============================================================================
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III.  Building the Simple DirectMedia Layer test programs:
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  After installing, making sure the correct sdl-config is in your
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  path, run configure like this:
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	NM=arm-linux-nm LD=arm-linux-ld CC=arm-linux-gcc CXX=arm-linux-g++ AR=arm-linux-ar ./configure arm-unknown-linux-gnu
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==============================================================================
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IV.  Application porting notes
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  One thing I have noticed is that applications sometimes don't exit
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  correctly. Their icon remains in the taskbar and they tend to
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  relaunch themselves automatically. I believe this problem doesn't
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  occur if you exit your application using the exit() method. However,
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  if you end main() with 'return 0;' or so, this seems to happen.
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  Also note that when running in landscape mode - i.e requesting a
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  window that is HEIGHT pixels wide and WIDTH pixels high, where WIDTH
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  and HEIGHT normally is 240 and 320 - the image is blitted so that
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  the hardware buttons are on the left side of the display. This might
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  not always be desirable but such is the code today.
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==============================================================================
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V.  Enjoy! :)
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  If you have a project you'd like me to know about, or want to ask questions,
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  go ahead and join the SDL developer's mailing list by sending e-mail to:
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	sdl-request@libsdl.org
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  and put "subscribe" into the subject of the message. Or alternatively you
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  can use the web interface:
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	http://www.libsdl.org/mailman/listinfo/sdl
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==============================================================================
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VI.  What is supported:
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Keyboard (Sharp Zaurus)
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Hardware buttons
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Stylus input (mouse)
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Video. Allows fullscreen both in portrait mode (up to WIDTHxHEIGHT
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size window) and in landscape mode (up to HEIGHTxWIDTH). 
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All other SDL functionality works like a normal Linux system (threads,
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audio etc).
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-- 
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David Hedbor <david@hedbor.org>
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http://david.hedbor.org/ 	http://eongames.com/
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