For Bubs

player.gd

extends CharacterBody2D

# ... variables
@onready var anim = $AnimationPlayer
@onready var sprite = $Sprite2D # Both assume you have an AnimationPlayer node as a child, and Sprite2D

var current_animation = "idle"

func _physics_process(delta: float) -> void:
  current_animation = "idle"
  var input = Input.get_vector("ui_left", "ui_right", "ui_up", "ui_down")
  if input.x > 0 and sprite.scale.x != 1:
    sprite.scale.x = 1
    current_animation = "run"
  elif input.x < 0 and sprite.scale.x != -1:
    sprite.scale.x = -1 # Make sure that, in the editor, you break the "chain" next to the sprite's scale by clicking the link icon
    current_animation = "run"
    
  if input.y < 0: # check for jump
    current_animation = "jump"
    velocity.y = -JUMP_STRENGTH # Whatever strength you define this to be
  
  if velocity.y > 0:
    current_animation = "fall"
  
  velocity.y += gravity * delta
  velocity.x = input.x
  
  if anim.current_animation != current_animation:
    anim.play(current_animation)