Portals - fix autolinking to internal rooms

Portal autolinking was previously agnostic to room priorities, which meant that portals would link to the first room they found (often outside rooms). This PR fixes this by making the autolinking priority aware, and will preferentially link to internal rooms.

scene/3d/room_manager.cpp

@@ -971,6 +971,9 @@ void RoomManager::_autolink_portals(Spatial *p_roomlist, LocalVector<Portal *> &
 
 			Vector3 test_pos = portal->_pt_center_world + (dist * portal->_plane.normal);
 
+			int best_priority = -1000;
+			int best_room = -1;
+
 			for (int r = 0; r < _rooms.size(); r++) {
 				Room *room = _rooms[r];
 				if (room->_room_ID == portal->_linkedroom_ID[0]) {
@@ -993,25 +996,37 @@ void RoomManager::_autolink_portals(Spatial *p_roomlist, LocalVector<Portal *> &
 				} // for through planes
 
 				if (!outside) {
-					// great, we found a linked room!
-					convert_log("\t\tAUTOLINK OK from " + source_room->get_name() + " to " + room->get_name(), 1);
-					portal->_linkedroom_ID[1] = r;
+					// we found a suitable room, but we want the highest priority in
+					// case there are internal rooms...
+					if (room->_room_priority > best_priority) {
+						best_priority = room->_room_priority;
+						best_room = r;
+					}
+				}
 
-					// add the portal to the portals list for the receiving room
-					room->_portals.push_back(n);
+			} // for through rooms
 
-					// send complete link to visual server so the portal will be active in the visual server room system
-					VisualServer::get_singleton()->portal_link(portal->_portal_rid, source_room->_room_rid, room->_room_rid, portal->_settings_two_way);
+			// found a suitable link room
+			if (best_room != -1) {
+				Room *room = _rooms[best_room];
 
-					// make the portal internal if necessary
-					// (this prevents the portal plane clipping the room bound)
-					portal->_internal = source_room->_room_priority > room->_room_priority;
+				// great, we found a linked room!
+				convert_log("\t\tAUTOLINK OK from " + source_room->get_name() + " to " + room->get_name(), 1);
+				portal->_linkedroom_ID[1] = best_room;
 
-					autolink_found = true;
-					break;
-				}
+				// add the portal to the portals list for the receiving room
+				room->_portals.push_back(n);
 
-			} // for through rooms
+				// send complete link to visual server so the portal will be active in the visual server room system
+				VisualServer::get_singleton()->portal_link(portal->_portal_rid, source_room->_room_rid, room->_room_rid, portal->_settings_two_way);
+
+				// make the portal internal if necessary
+				// (this prevents the portal plane clipping the room bound)
+				portal->_internal = source_room->_room_priority > room->_room_priority;
+
+				autolink_found = true;
+				break;
+			}
 
 		} // for attempt