Bullet field: pierce-through and damaging, rings spaced 3 cells apart

Solid bullets were blocking the patrolling enemies, so the field now defaults to solid = false: each bullet is a plain StaticBody2D with no collision layer, plus an Area2D that only detects the player, so nothing is physically obstructed while contact still costs a heart. Ring radii changed from [5, 10, 15] to [3, 6, 9]. Damage is now applied every frame to whatever is overlapping, not only on body_entered, so standing inside a bullet keeps hurting instead of only the first touch. Also picks up the editor change that removed Walker_03.

scripts/bullet_field.gd

@@ -1,14 +1,18 @@
 extends Node2D
 
 ## 静态弹幕障碍：以自己为圆心，一圈一圈地摆上**固定不动、不会发射**的子弹。
-## 默认只是纯障碍（实心，撞得到、能踩上去），把 damage 调大于 0 就变成碰到扣血。
-## 落在实心地砖里的子弹会自动跳过（不然会埋在地里）。
+##
+## 两种形态：
+##  - solid = true ：实心障碍，挡路、能踩上去（注意：会连小怪一起挡住）
+##  - solid = false：可以穿透，只做伤害判定 —— 配合 damage > 0 就是普通弹幕
+##
+## 落在实心地砖里、或跑出关卡范围的子弹会自动跳过。
 
 const BULLET_SCRIPT := preload("res://scripts/bullet.gd")
 
 @export var enabled: bool = true
-## 每一圈的半径（单位：格）。默认 5 格、10 格、15 格
-@export var radii_cells: Array[int] = [5, 10, 15]
+## 每一圈的半径（单位：格）。默认 3 格、6 格、9 格
+@export var radii_cells: Array[int] = [3, 6, 9]
 ## 每圈摆几颗
 @export var per_ring: int = 20
 ## 一格多少像素（图块是 18）
@@ -18,10 +22,10 @@ const BULLET_SCRIPT := preload("res://scripts/bullet.gd")
 ## 子弹半径
 @export var bullet_radius: int = 3
 @export var bullet_color: Color = Color(1.0, 0.45, 0.85)
-## 实心障碍：玩家撞得到、也能踩上去
-@export var solid: bool = true
-## 碰到扣几颗心。0 = 只是障碍不扣血
-@export var damage: int = 0
+## 实心障碍：挡路、能踩上去。关掉的话就是可以穿透的纯弹幕
+@export var solid: bool = false
+## 碰到扣几颗心。0 = 不扣血
+@export var damage: int = 1
 ## 超出这个范围的子弹不生成（默认整个关卡 468x270）
 @export var bounds: Rect2 = Rect2(0, 0, 468, 270)
 ## 最多铺几圈
@@ -33,6 +37,8 @@ var made: int = 0
 var skipped_out: int = 0
 var skipped_ground: int = 0
 
+var _hurt_areas: Array = []
+
 
 func _ready() -> void:
 	if not enabled:
@@ -47,6 +53,7 @@ func _build() -> void:
 	made = 0
 	skipped_out = 0
 	skipped_ground = 0
+	_hurt_areas.clear()
 	for i in mini(radii_cells.size(), max_rings):
 		var radius: float = float(radii_cells[i]) * cell_size
 		for k in per_ring:
@@ -62,6 +69,19 @@ func _build() -> void:
 			made += 1
 
 
+## 每帧检查一次：站在子弹里也会持续扣血
+## （不能只靠 body_entered —— 玩家本来就在子弹里的话不会触发）
+func _physics_process(_delta: float) -> void:
+	if damage <= 0 or _hurt_areas.is_empty():
+		return
+	for area in _hurt_areas:
+		if not is_instance_valid(area):
+			continue
+		for body in area.get_overlapping_bodies():
+			if body.has_method("hurt"):
+				body.hurt(damage)
+
+
 func _tile_layers() -> Array:
 	var root: Node = owner if owner != null else get_tree().current_scene
 	if root == null:
@@ -91,6 +111,7 @@ func _make(pos: Vector2, tex: Texture2D) -> void:
 		body.collision_layer = 1
 		body.collision_mask = 1
 	else:
+		# 不实心：谁都挡不住，只靠下面的伤害区域起作用
 		body.collision_layer = 0
 		body.collision_mask = 0
 	add_child(body)
@@ -118,9 +139,4 @@ func _make(pos: Vector2, tex: Texture2D) -> void:
 		hit.shape = circle2
 		area.add_child(hit)
 		body.add_child(area)
-		area.body_entered.connect(_on_hit)
-
-
-func _on_hit(body: Node2D) -> void:
-	if body.has_method("hurt"):
-		body.hurt(damage)
+		_hurt_areas.append(area)