First, this completely smashes joystick input: it will not work (though it
doesn't crash). This is because there is, as of yet, no means to configure
the system.
Each joystick axis has:
- per-axis amplification (both pre and post).
- per-axis offset (offset applied after pre-amp but before post amp)
- selectable destination:
- linear delta: position and angles (as before)
- axis button: if the value crosses the threshold, the given key is
pressed or released as appropriate.
The axis amplification still uses joy_amp and joy_pre_amp (and
in_amp/in_pre_amp), but now also has the per-axis settings.
The per-axis offset is most useful for axis buttons. For example, the xbox
360 controller triggers are analong but go "all the way to negative on 0
state". Offsetting the input keeps axis button thresholds simple.
Amplification and offset is applied before anything is done with the axis
value. The formula is:
joy_amp * in_amp * axis-amp *
(offset + value * joy_pre_amp * in_pre_amp * axis-pre_amp)
Axis button thresholds are very simple: if the sign of the value is the
same as the sign of the threshold and abs(value) >= abs(threshold), the
button is pressed. While multiple thresholds and keys can be placed on an
axis, only one can be pressed at a time. The threshold furthest from 0
wins.
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