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Bug 920

Summary: Haptic directions messed up on Linux
Product: SDL Reporter: elboato
Component: joystickAssignee: elboato
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: HG 2.0   
Hardware: All   
OS: Linux   
Attachments: linux specific file for haptic
SDL_syshaptic.c for Linux

Description elboato 2009-12-30 13:55:08 UTC 
Hey everybody!

I made further tests for my Java Joystick driver (http://sourceforge.net/projects/ffjoystick4java/) and I found out that the directions seem to be totally messed up on Linux.

note: directions mean the direction where the force comes from (e.g. force from south means that the stick moves away from the user).

I tested 5 directions with polar directions. "should be" is what I actually set as values, "is" is how the joystick behaved on Linux. On Windows it all worked fine.

should be  #         is
--------------------------------
northwest  # southeast --- WRONG
north      # south --- WRONG
south      # south --- CORRECT
east       # east --- CORRECT
west       # southeast --- WRONG

Then I changed the directions from polar to spherical. Again, on Windows everything worked as it should. On Linux the result is again weird, but also a little different compared to the previous one: west and east seem to be switched.

should be  #         is
--------------------------------
northwest  # southeast --- WRONG
north      # south --- WRONG
south      # south --- CORRECT
east       # southeast --- WRONG
west       # east --- WRONG

I looked at SDL_SYS_ToDirection in SDL_syshaptic.c in the linux directory of haptic, but I could not identify the problem yet. There's a comment: /* Linux directions are inverted. */

Maybe there's something wrong with that inversion " * 0xFFFF "?
Or maybe the values should be in another range, not from 0 to 36000?

All the best,

elboato
Comment 1 elboato 2010-01-07 05:53:30 UTC 
Created attachment 478 [details]
linux specific file for haptic
Comment 2 elboato 2010-01-07 06:03:51 UTC 
Alright... I corrected SDL_SYS_ToDirection in SDL_syshaptic.c in the linux directory of haptic. Now in all 3 cases the same value is returned, at least. Therefore now it should behave the same way as on Windows.

I added some comments and corrected the cases SDL_HAPTIC_CARTESIAN and SDL_HAPTIC_SPHERICAL.

Could you upload the file I attached to the SVN, please? see http://bugzilla.libsdl.org/attachment.cgi?id=478


So now I still have another problem: my Joystick (Logitech Force 3D Pro) does only work correctly for the directions south, east and south-east. (values for directions on driver/system level: 0, 49151 (0xC000) and 57343 (0xE000). Well so far I only tried the 8 default directions. I'll take a closer look. I have no clue what might be the problem. Maybe it's the driver itself... Any ideas?

All the best

elboato
Comment 3 elboato 2010-01-07 08:17:49 UTC 
(In reply to comment #2)
> So now I still have another problem: my joystick (Logitech Force 3D Pro) does
> only work correctly for the directions south, east and south-east. (values for
> directions on driver/system level: 0, 49151 (0xC000) and 57343 (0xE000). Well
> so far I only tried the 8 default directions. I'll take a closer look. I have
> no clue what might be the problem. Maybe it's the driver itself...

As I supposed: in SDL_SYS_HapticUpdateEffect the effect is uploaded with ioctl(haptic->hwdata->fd, EVIOCSFF, &linux_effect) and there the values in the struct linux_effect are okay. So the problem seems to be the driver for my joystick Logitech Force 3D Pro.

Can anybody confirm that? If I'm right, I guess this bug is resolved with the file I attached before....

And can anybody suggest a joystick that works on linux? Which joysticks/gamepads were used/tested during the implementation of haptic for SDL?

Thx in advance!

elboato
Comment 4 elboato 2010-01-18 01:37:49 UTC 
Created attachment 481 [details]
SDL_syshaptic.c for Linux

I added even more comments on the corrected conversion to Linux directions. This was tested on my Logitech Force 3D Pro Joystick and it should definitely work.
Comment 5 Sam Lantinga 2010-01-18 06:57:16 UTC 
Your changes are in subversion, thanks!