author Sam Lantinga <>
Thu, 02 Apr 2009 04:43:36 +0000
changeset 4167 a6f635e5eaa6
parent 471 26dafefeebb2
permissions -rw-r--r--
Fixed bug #611

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

I'm one of the maintainers of, 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
( 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   Patch version 0.9 of SDL(Simple DirectMedia Layer) for Nano-X API
     3   =================================================================
     5   Authors: Hsieh-Fu Tsai,
     6            Greg Haerr,
     8   This patch is against SDL version 1.2.4.
     9   It enhances previous patch 0.8 by providing direct framebuffer
    10   access as well as dynamic hardware pixel type support, not
    11   requiring a compile-time option setting for different framebuffer
    12   modes.
    13   Tested against Microwindows version 0.89pre9.
    15   Older Microwindows versions
    16   ===========================
    17   If running on a version older than Microwindows 0.89pre9,
    18   the following items might need to be patched in Microwindows.
    20   1. Patch src/nanox/client.c::GrClose()
    21   It fixes the client side GrClose(). In the original version, 
    22   GrOpen() can only be called once. When the GrOpen() is called at 
    23   the second time, the program will terminate. In order to prevent
    24   this situation, we need to insert "nxSocket = -1" after 
    25   "close(nxSocket)" in GrClose(). If you do not have this problem,
    26   you may skip this step. 
    28   2. Patch src/nanox/clientfb.c to return absolute x,y coordinates
    29   when using GrGetWindowFBInfo().  Copy the version 0.89pre9
    30   of src/nanox/clientfb.c to your system, or configure
    31   using --disable-nanox-direct-fb.
    33   =============
    34   Quick Install 
    35   =============
    37   1. ./configure --disable-video-x11 --disable-video-fbcon \ 
    38        --enable-video-nanox \ 
    39        --with-nanox-pixel-type=[rgb/0888/888/565/555/332/pal] 
    40   2. make clean 
    41   3. make 
    42   4. make install (as root) 
    44   ============
    45   Nitty-gritty 
    46   ============
    48   --enable-nanox-direct-fb       Use direct framebuffer access
    49   --enable-nanox-debug           Show debug messages 
    50   --enable-nanox-share-memory    Use shared-memory to speed up 
    52   When running multi-threaded applications using SDL, such
    53   as SMPEG, set THREADSAFE=Y in Microwindows' config file,
    54   to enable GrXXX() system call critical section support.
    56   =============================================
    57   Some programs can be used to test this patch. 
    58   =============================================
    60   1. (a tetris-like game) 
    61   2.
    62   3.
    63   4. 
    64   5. 
    65   6: (SMPEG version 0.4.4)
    67   =========
    68   Todo List 
    69   =========
    71   1. Create hardware surface
    72   2. Create YUVOverlay on hardware
    73   3. Use OpenGL
    74   4. Gamma correction
    75   5. Hide/Change mouse pointer
    76   6. Better window movement control with direct fb access
    77   7. Palette handling in 8bpp could be improved
    79   =====================
    80   Supporting Institutes
    81   =====================
    83   Many thanks to go to Setabox Co., Ltd. and CML (Communication and
    84   Multimedia Laboratory, in the 
    85   Department of Computer Science and Information Engineering of 
    86   National Taiwan University for supporting this porting project.
    88   Century Embedded Technologies (
    89   for this patch.
    91   ===================
    92   Contact Information
    93   ===================
    95   Welcome to give me any suggestion and to report bugs.
    96   My e-mail address : or
    97                       or