Rework elevator gameplay around pulse-blocking and per-floor spawning

scenes/node_3d.gd

@@ -0,0 +1,43 @@
+extends Node3D
+
+@export var spawn_position := Vector3(0, 0, -20)
+@export var spawn_spread := 2.0                 
+@export var spawn_interval := 1.5               
+
+var survivor_scene := preload("res://scenes/survivor.tscn")
+var survivors_to_spawn := 0
+var spawn_timer: Timer
+
+func start_spawning(count: int):
+	survivors_to_spawn = count
+	if not spawn_timer:
+		spawn_timer = Timer.new()
+		spawn_timer.one_shot = false
+		spawn_timer.wait_time = spawn_interval
+		spawn_timer.timeout.connect(_spawn_one)
+		add_child(spawn_timer)
+	spawn_timer.start()
+	_spawn_one()  # first one immediately
+
+func stop_spawning():
+	if spawn_timer:
+		spawn_timer.stop()
+	survivors_to_spawn = 0
+
+func _spawn_one():
+	if survivors_to_spawn <= 0:
+		if spawn_timer:
+			spawn_timer.stop()
+		return
+
+	var survivor = survivor_scene.instantiate()
+	var offset_x = randf_range(-spawn_spread, spawn_spread)
+	var xform = Transform3D()
+	xform.origin = spawn_position + Vector3(offset_x, 0, 0)
+	survivors_to_spawn -= 1
+	_deferred_add.call_deferred(survivor, xform)
+
+func _deferred_add(survivor, xform):
+	get_tree().current_scene.add_child(survivor)
+	survivor.owner = get_tree().current_scene
+	survivor.start(xform)