[Bug 42137] New: DirectInput needs to join both Xbox shoulder triggers into a single axis (aka half-axis problem)

https://bugs.winehq.org/show_bug.cgi?id=42137

Bug ID: 42137
           Summary: DirectInput needs to join both Xbox shoulder triggers
                    into a single axis (aka half-axis problem)
           Product: Wine
           Version: 1.6.1
          Hardware: x86
                OS: Linux
            Status: NEW
          Keywords: hardware
          Severity: normal
          Priority: P2
         Component: directx-dinput
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail]
      Distribution: ---

When MS introduced the Xbox controller into dinput it had the idea of joining
both Xbox controller shoulder triggers into a single axis. So the left trigger
ranges to the negative side while the right trigger to the positive side of the
same axis.

Wine currently exposes the triggers are separate axes Z and rZ, this affects
some games negatively because the not-pressed default values for the triggers
is the lowest possible, for example if the axis ranges from -100 to +100 Wine
exposes -100 to the application. The effect is that the application thinks the
axis is always pressed and weird things happen, eg auto selecting Z/rZ as every
button when configuring a joystick or wrongly selecting Z/rZ as rX/rY making
FPS players always look up or down.

I don't know if this happens only for Xbox controllers but I believe so. I'll
have the chance to test with a real PS3 controller soon.

If that is MS only, we need to find a way to distinguish the joysticks
(VID/PID?) and merge the axes to mimic MS behavior.

At the same time and in opposite direction the XInput API does not employ this
hack, since XInput was made for Xbox only controllers it will properly report
the values for the axes separately.