README.PicoGUI
author Sam Lantinga <slouken@libsdl.org>
Thu, 02 Apr 2009 04:43:36 +0000
branchSDL-1.2
changeset 4167 a6f635e5eaa6
parent 433 706de3956894
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.
     1  ========================
     2   Using SDL with PicoGUI
     3  ========================
     4 
     5 - Originally contributed by Micah Dowty <micahjd@users.sourceforge.net>
     6 
     7 PicoGUI is a scalable GUI system with a unique architecture, primarily focused
     8 on scalability to various embedded systems. You can find more information
     9 including a FAQ at http://picogui.org
    10 
    11 To use the patch:
    12 
    13   1. When compiling, add the "--enable-video-picogui" switch to ./configure
    14 
    15   2. When running your program, ensure that the picogui driver for SDL
    16      is in use by setting the SDL_VIDEODRIVER environment variable 
    17      to "picogui".
    18 
    19   3. The program must also be linked to the C client library for PicoGUI
    20      (libpgui.so). If the program is being compiled with a patched SDL 
    21      installed this should be done automatically. If you want to use an
    22      existing binary with PicoGUI, you can set the LD_PRELOAD environment
    23      variable to the path of your libpgui.so file.
    24 
    25 Capabilities:
    26 
    27   So far only basic functionality is provided on true color (linear16/24/32)
    28   devices. Accessing a memory mapped bitmap, updating the display, and handling
    29   mouse/keyboard input. This functionality has been tested with several
    30   applications, including mplayer, Xine, sldroids, and Abuse.
    31 
    32 TODO list:
    33 
    34   - YUV overlays will be helpful for watching video on set top boxes or other
    35     embedded devices that have some graphics acceleration hardware
    36 
    37   - Account for rotated bitmap storage in pgserver
    38 
    39   - Support for hiding or changing the cursor
    40 
    41   - The display should be centered when the SDL application is smaller
    42     than the PicoGUI panel
    43 
    44   - Fullscreen or any other special modes
    45 
    46   - Support for indexed and grayscale modes
    47 
    48   - Probably much more...
    49 
    50 --- The End ---