Input and games.

[Pekka Paalanen]

On Sat, 27 Apr 2013 15:02:59 -0400
Todd Showalter <todd at electronjump.com> wrote:

> On Sat, Apr 27, 2013 at 10:23 AM, nerdopolis
> <bluescreen_avenger at verizon.net> wrote:
> 
> > What about rumblepads? How would the protocol control the rumblepad
> > in some controllers?
> 
>     I think rumble is beyond the scope of the proposed gamepad
> protocol.  The problem is that (at least in my experience) whereas
> many controllers have some form of rumble, the actual physical rumble
> hardware has very little in common between devices.  Some things have
> linear motors, some have rotary motors.  Some have both.  Or multiples
> of one or the other.  Some (like the wiimote, IIRC) aren't actually
> rumble per se, and are actually a speaker you stream sound to at low
> bit rates.
> 
>     The other problem (at least to me) is that rumble flows in the
> opposite direction from input; in the gamepad protocol I'm proposing,
> all the data is flowing from the hardware through the server to the
> application.  Rumble runs the other way.  Rumble in general is far
> more akin to sound playback than it is to input; you're basically
> feeding a control stream to an actuator.
> 
>     Beyond that, at least with some gamepads, the rumble hardware is
> subject to restrictions; in particular, at least one bit of kit I've
> worked with that's still in circulation doesn't get enough power over
> the controller cable to run all of the rumble motors at the same time,
> and if you turn too much on the board-level logic in the gamepad can
> start acting wonky.
> 
>     So, the short version of my answer is (1) I think rumble is a
> totally different problem domain that wants its own protocol, and (2)
> I'm not sure there's enough commonality or sanity in rumble hardware
> to build a useful protocol.

Sounds like this should definitely be punted to the evdev file
descriptor passing interface. There the game needs to know (via a
library or by itself) how to drive the particular controller, anyway.
And the display server will not be in the way for relaying rumble
commands.


Thanks,
pq