Add a page about gamepad/controller support in Godot

[Calinou]

This is a first pass at documenting controller support in Godot. Feel free to suggest additional things to document.

@aaronfranke I know that you worked on getting input actions on multiple directions for 3.2.4, and I remember this being useful to implement proper deadzone calculations for 2D top-down movement. Could you explain this a little? I don't really know how to document it, but it would be good to have the documentation page explain how to handle dead zones properly in this situation.

[aaronfranke]

This article is missing information about the most important part: What code should people use? It only mentions that the code paths are the same between keyboard input and controller input, but not what those code paths are.

• For joysticks and WASD etc when you have two axes, want both axes to behave as one input, and for input to be in the form of a Vector2 such as for movement or looking, starting with Godot 4.0, Input.get_vector should be used.

• For other types of axis input, such as if you want to handle joystick axes individually, or you have a device where an axis is by itself (such as the throttle on a flight stick), starting with Godot 4.0, Input.get_axis should be used.

• For other types of analog input, such as if you are handling a trigger, or only care about one direction on a joystick, or want to handle one direction at a time, starting with Godot 3.1, Input.get_action_strength should be used.

• For binary input, if you only want a true or false value, or if the input is inherently binary such as mouse buttons, controller face buttons/start/select/joystick clicks/bumpers, and keyboard keys (except for keys handled as vectors/axes), in pretty much any Godot version, Input.is_action_pressed should be used.

[aaronfranke]

Looks good to me now. I made a few fixes and tweaks and added C# example code, let me know what you think @Calinou.

[aaronfranke]

Note: This is technically not true just yet, but godotengine/godot-demo-projects#575 was merged, so this sentence will be true the next time I make a release of the demos on the Godot Asset Library.

[Calinou]

@aaronfranke Changes look good to me 🙂

[groud]

This is false in fact. One of the advantages of the using get_vector over this is the handling of the deadzone.
With this solution the deazone end up square instead of circular.

I'm ok with mentionning that they are similar but it's false to say they are equivalent.

[Calinou]

PR opened: #4651

[akien-mga]

Cherry-picked for 3.3.