Bullet rain is denser and its bullets are no longer stopped by anything

Interval dropped from 1.0s +- 0.6 to 0.4s +- 0.25 (about 2.5 bullets per second instead of 1), which measured 13 drops in 6 seconds versus 6 before. bullet.gd gained stop_on_obstacle (default false): the probe raycast is disabled, so rain bullets fall straight through terrain and ropes and are only recycled by their lifetime or by dropping past despawn_y. Verified a bullet falling from y=190 goes through the floor at y=225 and despawns at y=340. Also picks up the editor changes: the rope tiles were removed from level 3 and a few nodes gained unique ids.

scripts/bullet.gd

@@ -1,6 +1,6 @@
 extends Area2D
 
-## 弹幕子弹：直线飞行，碰到玩家扣血，撞到地形或超时消失。
+## 弹幕子弹：直线飞行，碰到玩家扣血。
 ## 贴图是代码生成的实心圆，不需要额外美术素材。
 
 @export var speed: float = 70.0
@@ -8,6 +8,11 @@ extends Area2D
 @export var lifetime: float = 8.0
 @export var radius: int = 3
 @export var bullet_color: Color = Color(1.0, 0.35, 0.7)
+## 撞到地形/绳子之类的障碍就消失。
+## 关掉（默认）的话子弹会**穿过一切**，只靠存活时间和出界来回收
+@export var stop_on_obstacle: bool = false
+## 掉到这个世界 y 以下就自动回收（默认在关卡底部之外）
+@export var despawn_y: float = 340.0
 
 var direction: Vector2 = Vector2.LEFT
 
@@ -48,6 +53,8 @@ func _ready() -> void:
 		circle.radius = float(radius)
 		hit.shape = circle
 	_probe = get_node_or_null("Probe") as RayCast2D
+	if _probe != null:
+		_probe.enabled = stop_on_obstacle
 	body_entered.connect(_on_body_entered)
 
 
@@ -59,12 +66,12 @@ func launch(dir: Vector2, spd: float = -1.0) -> void:
 
 func _physics_process(delta: float) -> void:
 	_age += delta
-	if _age >= lifetime:
+	if _age >= lifetime or global_position.y > despawn_y:
 		queue_free()
 		return
 
 	var step := direction * speed * delta
-	if _probe != null:
+	if stop_on_obstacle and _probe != null:
 		_probe.target_position = step * 1.5
 		_probe.force_raycast_update()
 		if _probe.is_colliding():