chore: modifiers are aware of parent terrain

modules/terrain/terrain.cpp

@@ -9,16 +9,27 @@ void Terrain::_bind_methods() {
 	BIND_PROPERTY(Variant::INT, thread_count);
 }
 
-void Terrain::ready() {
-	construct_chunk_grid();
+void Terrain::child_order_changed() {
+	this->modifiers.clear();
+	for (Variant var : get_children()) {
+		if (TerrainModifier * mod{ cast_to<TerrainModifier>(var) }) {
+			mod->set_terrain(this);
+			this->modifiers.push_back(mod);
+		}
+	}
 }
 
 void Terrain::_notification(int what) {
 	switch (what) {
 		default:
 			return;
+		case NOTIFICATION_ENTER_TREE:
+			if (!is_ready()) {
+				connect("child_order_changed", callable_mp(this, &self_type::child_order_changed));
+			}
+			return;
 		case NOTIFICATION_READY:
-			ready();
+			construct_chunk_grid();
 			return;
 		case NOTIFICATION_EXIT_TREE:
 			this->workload_lock.lock();