Input event for gamepad buttons.
Input event type for gamepad buttons. For joysticks see [InputEventJoypadMotion].
http://docs.godotengine.org/en/3.0/learning/features/inputs/inputevent.html
Button identifier. One of the [code]JOY_BUTTON_*[/code] constants from [@global Scope].
If [code]true[/code] the button's state is pressed. If [code]false[/code] the button's state is released.
Represents the pressure the user puts on the button with his finger, if the controller supports it. Ranges from [code]0[/code] to [code]1[/code].