Color red entities that would be deleted on placement

interface/ghost/ghost.gd

@@ -57,8 +57,6 @@ func _ready():
 
 ## Update the value of [can_place].
 func update_state():
-	overlap_checker.update_is_overlapping_with()
-	placeable_area_checker.update_is_overlapping_with()
 	# DIRTY HACK: Relies on the placeable area being perfectly surrounded by solid bodies.
 	can_place = overlap_checker.is_overlapping_with == null and placeable_area_checker.is_overlapping_with != null
 
@@ -103,8 +101,31 @@ func materialize() -> Node:
 
 
 func _on_moved(_from, _to):
+	overlap_checker.update_is_overlapping_with()
+	overlap_freer.update_is_overlapping_with()
+	placeable_area_checker.update_is_overlapping_with()
 	update_state()
 
-
 func _on_rotated_radians(_from, _to):
+	overlap_checker.update_is_overlapping_with()
+	overlap_freer.update_is_overlapping_with()
+	placeable_area_checker.update_is_overlapping_with()
+	update_state()
+
+func _on_area_entered(_area):
+	placeable_area_checker.update_is_overlapping_with()
+	update_state()
+
+func _on_area_exited(_area):
+	placeable_area_checker.update_is_overlapping_with()
+	update_state()
+
+func _on_body_entered(_body):
+	overlap_checker.update_is_overlapping_with()
+	overlap_freer.update_is_overlapping_with()
+	update_state()
+
+func _on_body_exited(_body):
+	overlap_checker.update_is_overlapping_with()
+	overlap_freer.update_is_overlapping_with()
 	update_state()

interface/ghost/ghost.tscn

@@ -34,9 +34,9 @@ overlap_mask = 16
 [node name="OverlapFreer" parent="." instance=ExtResource("6_y1rxa")]
 overlap_mask = 4
 
-[connection signal="area_entered" from="." to="PlaceableAreaChecker" method="update_is_overlapping_with"]
+[connection signal="area_entered" from="." to="." method="_on_area_entered"]
-[connection signal="area_exited" from="." to="PlaceableAreaChecker" method="update_is_overlapping_with"]
+[connection signal="area_exited" from="." to="." method="_on_area_exited"]
-[connection signal="body_entered" from="." to="OverlapChecker" method="update_is_overlapping_with"]
+[connection signal="body_entered" from="." to="." method="_on_body_entered"]
-[connection signal="body_exited" from="." to="OverlapChecker" method="update_is_overlapping_with"]
+[connection signal="body_exited" from="." to="." method="_on_body_exited"]
 [connection signal="moved" from="PreciseTouchPlacer" to="." method="_on_moved"]
 [connection signal="rotated_radians" from="PreciseTouchPlacer" to="." method="_on_rotated_radians"]

interface/ghost/overlap_freer.gd

@@ -11,12 +11,30 @@ class_name OverlapFreer
 @export var overlap_with_tilemap: bool = false
 
 
+## Color to restore modulation on objects that wouldn't be deleted anymore.
+@export var valid_color: Color = Color.WHITE
+
+## Color to modulate objects that would be deleted if [area_queue_free] was called right now.
+@export var invalid_color: Color = Color.RED
+
+
+var is_overlapping_with: Array[Node2D] = []:
+	get:
+		return is_overlapping_with
+	set(value):
+		for body in is_overlapping_with:
+			body.modulate = valid_color
+		for body in value:
+			body.modulate = invalid_color
+		is_overlapping_with = value
+
+
 ## The [Area2D] this script should act on.
 @onready var target: Area2D = get_parent()
 
 
 ## Get all bodies overlapping the [target].
-func get_all_overlapping_bodies() -> Array[Node2D]:
+func update_is_overlapping_with() -> void:
 	var bodies: Array[Node2D] = []
 	for body in target.get_overlapping_bodies():
 		if body is TileMap:
@@ -25,9 +43,9 @@ func get_all_overlapping_bodies() -> Array[Node2D]:
 		elif body is PhysicsBody2D:
 			if body.collision_layer & overlap_mask:
 				bodies.append(body)
-	return bodies
+	is_overlapping_with = bodies
 
-## Emitted when a body is about to be [queue_free]d.
+## Emitted when a body is about to be [queue_free]d by [area_queue_free].
 signal queueing_free(body: Node2D)
 
 ## Queue free the passed nodes.
@@ -38,4 +56,4 @@ func mass_queue_free(nodes: Array[Node2D]):
 
 ## Queue free all overlapping bodies.
 func area_queue_free() -> void:
-	mass_queue_free(get_all_overlapping_bodies())
+	mass_queue_free(is_overlapping_with)