Godot 4 modular sway component to bounce the y position of a parent, up and down.

sway_component.gd

class_name SwayComponent extends Node

@export var sway_distance: float = 32
@export var sway_duration: float = 2

@onready var start_y: float = y

var y: float:
	set(value):
		var parent := get_parent()
		if !parent:
			return
		
		parent.set_indexed("position:y", value)
	get:
		var parent := get_parent()
		if !parent:
			return 0
		
		var value = parent.get_indexed("position:y")
		if value == null:
			value = 0
		return value

func _process(_delta: float) -> void:
	y = start_y + sin(TAU * Time.get_ticks_msec() / 1000.0 / sway_duration) * sway_distance