Split UserInput into multiple traits

[alice-i-cecile]

I had previously considered splitting it into different input kinds: Button, Axis, DualAxis, etc.; and there are corresponding data types for each. Then, modify the ActionState API, something like this:

if let ButtonState(state) = action_state.get(ButtonAction) {
   let pressed = state.pressed;
   let pressure = state.pressure; // Gamepad buttons are ranging from 0 to 1, and others are 0 or 1
}
if let AxisValue(value: f32) = action_state.get(AxisAction) {
}

Originally posted by @Shute052 in #490 (comment)

[alice-i-cecile]

The basic design I'm going to go with is a core UserInput trait with the bare minimum of functionality.

Then, three other traits that imply UserInput: ButtonlikeInput, SingleAxisInput, DualAxisInput.

[Shute052]

I was thinking of having an InputData enum for buttons, single-axis inputs, and dual-axis ones.
However, there's an issue with Chord in that context. It can consist of multiple single-axis inputs and multiple dual-axis inputs (but only considers the first dual-axis data).

[alice-i-cecile]

Yeah, I think that we need to restrict chords to only contain buttonlike inputs, and then make sure there's general-purpose ways to turn axislikes into buttonlikes.

I'll tackle this and ping you for review :)

[Shute052]

I think that we need to restrict chords to only contain buttonlike inputs

But in some cases, Chord with single-/dual-axis inputs can be really useful. For instance, in my project, I've implemented mouse drag using a Chord.

Perhaps we could consider making a Chord consist of either only buttons, only buttons with single-axis inputs, or only buttons with dual-axis inputs?

[alice-i-cecile]

Hmm 🤔 Okay, I'll leave it for now and chew on it.