create bubble environmental particle

objects/environment/bubble/bubble.gd

@@ -0,0 +1,22 @@
+extends Area2D
+
+export var speed = 16.0
+
+onready var sprite = $Sprite
+
+var lifetime = 0.0
+
+func _ready():
+	sprite.frame_coords.x = randi() % sprite.hframes
+
+func _physics_process(delta):
+	lifetime += delta
+	if speed > 0.0:
+		sprite.position.x = sin(lifetime * 4.0) * 4.0
+	position.y -= speed * delta
+
+func _on_area_entered(area):
+	if area.is_in_group("player") or area.is_in_group("arrow"):
+		sprite.frame_coords.y = 1
+		speed = 0.0
+		get_tree().create_timer(0.5, false).connect("timeout", self, "queue_free")