[AD] Problems with gamepad on MacOS X and general thoughts

[Max Savenkov <max.savenkov@xxxxxxxxxx>]

First, MacOS X gamepad code assumes that number of sticks on device is 
equivalent to number of X axes. This is not always true: for my gamepad, 
there are 1 reported X axis, 1 Y axis and 2 Z axis. Currently, the extra 
Z axis gets lost for Allegro :) I think this piece of code needs to be 
rewritten not to assume number of sticks in this way.

MaxOS X gamepad code also can't handle d-pad on my gamepad. It has usage 
== kHIDUsage_GD_Hatswitch and needs special handling, because its 
element represents both axes at once (or maybe it should be mapped to 
four buttons?).

I think I can fix those two problems myself, but first I'd like to talk 
about a more general thing: I see that Allegro's idea of separate 
"sticks" fails on so many platforms it seems to be useless. Time and 
time again I get sticks with 3 axes for my gamepad. Mostly, X-axis of my 
right sticks gets reported as Z-axis of the left stick. I think this is 
a problem with drivers, but it's a problem Allegro can't correct, and it 
leads to confusion. I know that would be a backward compatibility 
breaking change, but maybe we should consider abandoning the idea of 
sticks, and return to a set of independent axes instead, as with SDL? 
The current setup gives end-user false sense of security, he might think 
that 0th axis of a stick always will be horizontal, and 1st axis will be 
vertical, and there can be no 2nd axis on a standard gamepad. But this 
is not true :)

As an alternative, we may retain the current setup, but finally give 
users controller database, so they might treat sticks and axes reported 
by joystick events as "magic", opaque values, from which the REAL 
controls might be obtained by querying controller DB (i.e., for my 
gamepad, stick 0 axis 3 will map to stick 1 axis 0). This keeps backward 
compatibility, but will multiply user confusion. Moving away from sticks 
would allow to simplify joystick drivers for all platforms somewhat, and 
give us a bit more compatibility with SDL.