improve linux joystick detection #902

allefant · 2018-04-14T03:01:10Z

This correctly identifies X/Y/Z axes as well as common button types.
More work needs to be done but this also adds enough log information
that someone could just send us an allegro.log and we could improve from
that.

My old xbox 360 controller has 100% of axes and buttons correctly
identified with his.

Before the patch all the buttons were just named B and the axes were
mapped completely wrong, mapping triggers as axes and swapping X and Y
axes of the sticks.

This correctly identifies X/Y/Z axes as well as common button types. More work needs to be done but this also adds enough log information that someone could just send us an allegro.log and we could improve from that. My old xbox 360 controller has 100% of axes and buttons correctly identified with his. Before the patch all the buttons were just named B and the axes were mapped completely wrong, mapping triggers as axes and swapping X and Y axes of the sticks.

fatcerberus · 2018-04-14T04:03:52Z

Does this work properly with non-Xbox gamepads? I know we've had issues with Xbox controllers in the past where attempting to fix them breaks things with other devices.

allefant · 2018-04-14T04:18:59Z

I don't know. But if you look at the changes the old code just was wrong - e.g. it simply ignored whether axes are X/Y/Z and just alternated between X and Y. And it completely ignored the button type. So I would say the chance that the new code is any worse than the old is close to zero :)

Still - do you have any more information about those issues you had in the past?

igormorgado

just a readout

igormorgado · 2018-04-14T05:48:04Z

examples/ex_joystick_events.c

-      if (strlen(name) < 4) {
-         al_draw_text(font, fg, x + 13, y + 8, ALLEGRO_ALIGN_CENTRE, name);
+      char name2[4];
+      if (strlen(name) >= 4) {


is this not the case for a strncpy?

strncpy(name2, name, 3);

I don't think so - strncpy will not copy the final 0.

igormorgado · 2018-04-14T05:53:49Z

about the axis auto discovery, I think (cannot test all joysticks in the world) that will probably break something, SDL went to the path to manual configuration instead auto discovery. They probably had a good reason for that.

fatcerberus · 2018-04-14T06:39:33Z

Still - do you have any more information about those issues you had in the past?

They weren't my issues--I just remember there being a good amount of discussion in the past w.r.t. incorrect behavior for Xbox controllers; I'm also pretty sure I remember a fix being reverted because it turned out to break other things.

edit: This was the reverted change I was thinking of: #662
It seems that was a change specifically for macOS, so might not be relevant to this PR after all. Feel free to pretend I didn't say anything 😄

allefant · 2018-04-14T12:43:21Z

Let's see if someone can test it with one or two other joysticks. If something currently has 4 axes and designates them all as X axis, it would still show up as 2 sticks with X/Y axis each right now, since the current code completely ignores the designation. My change would make it show up as 4 sticks with a single X axis each. So yes, I can see cases where something would end up worse than before if evdev returns wrong information to begin with. (With my only test device evdev returns correct information.)

I looked at the SDL axis/button database and it is very easy to use: https://github.com/gabomdq/SDL_GameControllerDB/blob/master/gamecontrollerdb.txt

And it also means the mapping would be identical under Windows and OSX so it would be a big advantage. However it seems SDL is actually using this only in their GameController API - their Joystick API works the same as ours and does not use that database at all, just a direct mapping. So we probably would have to investigate this a bit more and maybe also use an additional API for it.

SiegeLord · 2018-04-21T20:17:35Z

Alright, I tested this with 2 of my joysticks, 3 configurations (F310 has a physical switch between DInput and XInput).

Current code

F310, XInput

11 buttons (sees the center button)
4 2D sticks, triggers and right thumb mixed up between 2 sticks

F310, DInput

12 buttons, (triggers as buttons, no center button)
3 2D sticks

PSX controller in adapter

12 buttons (triggers as buttons, but this is fine as PSX controller has no pressure sensitivity for triggers)
3 2D sticks

New code

F310 XInput

11 buttons (have names, center button detected), side bumpers incorrectly called triggers
2 3D sticks (triggers + thumbs combined)

F310 DInput

12 buttons (triggers as buttons)
1 3D stick, combining left thumb + one axis of right thumb
1 1D stick, other axis of right thumb
1 2D stick, D-pad

PSX controller in adapter

Same as F310 DInput above, screwed up sticks

So... hit and miss. The only concrete improvement are the button names for one of the controllers (although still not usable as is, as it calls side bumpers triggers).

beoran · 2018-04-22T06:43:06Z

I found this Linux kernel doc on joypads that may be helpful. The problem is that what the linux driver reports and what the button, trigger or axis really is may not always be easy to map. Nevertheless this doc suggests a way of doing it which we don't implement. Perhaps we should try what the doc suggests. https://www.kernel.org/doc/html/latest/input/gamepad.html

…

On Sat, 21 Apr 2018, 22:17 SiegeLord, ***@***.***> wrote: Alright, I tested this with 2 of my joysticks, 3 configurations (F310 has a physical switch between DInput and XInput). Current code FX310, XInput - 11 buttons (sees the center button) - 4 2D sticks, triggers and right thumb mixed up between 2 sticks FX310, DInput - 12 buttons, (triggers as buttons, no center button) - 3 2D sticks PSX controller in adapter - 12 buttons (triggers as buttons, but this is fine as PSX controller has no pressure sensitivity for triggers) - 3 2D sticks New code F310 XInput - 11 buttons (have names, center button detected), side bumpers incorrectly called triggers - 2 3D sticks (triggers + thumbs combined) F310 DInput - 12 buttons (triggers as buttons) - 1 3D stick, combining left thumb + one axis of right thumb - 1 1D stick, other axis of right thumb - 1 2D stick, D-pad PSX + adapter - Same as F310 DInput above, screwed up sticks So... hit and miss. The only concrete improvement are the button names for one of the controllers (although still not usable as is, as it calls side buttons triggers). — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#902 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAEWecn_bEN6TwLa_g2-Or1uUD10BZR5ks5tq5PfgaJpZM4TU5p5> .

allefant · 2018-04-22T12:36:19Z

Are we still not doing this with the PR? (except for the part about legacy drivers which is in fact keeping a custom database for those yourself)

beoran · 2018-04-23T03:52:04Z

No, not quite. For game pads there seems to be a definite mapping for the axes of the sticks and the triggers that neither the old code nor this pr implements.

…

On Sun, 22 Apr 2018, 14:36 allefant, ***@***.***> wrote: Are we still not doing this with the PR? (except for the part about legacy drivers which is in fact keeping a custom database for those yourself) — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#902 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAEWeUBV4soxLDa84aTHQJlHbdKK6hiOks5trHlDgaJpZM4TU5p5> .

elias-pschernig · 2018-04-23T16:43:48Z

I re-read it, I feel that's exactly what the PR does, maybe minus some smaller things. But the main problem is it seems two of SiegeLord's joystick simply do not follow the new Linux kernel guidelines at all, likely using some kind of legacy driver from before those gamepad specifications were written. The only way to make those work seems to be (as that document admits) to keep a database of device uuids and hardcode a mapping for them.

beoran · 2018-04-23T18:33:06Z

Well, Allegro already used Allegro.cfg for configuring and dealing with all sorts of hardware problems. I guess introducing some more settings for Linux Joysticks is pretty much inevitable if we want all devices to work well.

…

On Mon, 23 Apr 2018, 18:43 elias-pschernig, ***@***.***> wrote: I re-read it, I feel that's exactly what the PR does, maybe minus some smaller things. But the main problem is it seems two of SiegeLord's joystick simply do not follow the new Linux kernel guidelines at all, likely using some kind of legacy driver from before those gamepad specifications were written. The only way to make those work seems to be (as that document admits) to keep a database of device uuids and hardcode a mapping for them. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#902 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAEWeVUq5M7KNhbhgfPMXlepN38GFQWsks5trgTEgaJpZM4TU5p5> .

SiegeLord · 2018-04-28T16:50:52Z

I'd argue that none of my controllers are mapped correctly. The correct mapping for F310 (and the XBox controller it is emulating) is 11 butons, 2 1D axes for the triggers and 2 2D axes for the analog sticks. I think we should hold off on merging this code until we got a remapping setup in place.

fatcerberus · 2018-04-28T16:54:55Z

2 1D axes for the triggers

I note for the record that Windows itself seems to treat Xbox controllers as having a single 1D axis which is the sum of both triggers. Kind of weird. No idea if this is the same for other platforms.

SiegeLord · 2018-04-28T17:54:13Z

Hmm... well, for me on Windows Allegro does treat F310's triggers as 2 1D sticks (interestingly, it treats the D-pad as separate 4 buttons, and doesn't detect the center button). Notable, F310 in DInput mode is not detected at all!

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improve linux joystick detection #902

improve linux joystick detection #902

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improve linux joystick detection #902

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Current code

F310, XInput

F310, DInput

PSX controller in adapter

New code

F310 XInput

F310 DInput

PSX controller in adapter

beoran commented Apr 22, 2018 via email

allefant commented Apr 22, 2018

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