From 6b79201d217b4be54bb02ea4622bfa30a606afa6 Mon Sep 17 00:00:00 2001
From: Dustin Carlino <dabreegster@gmail.com>
Date: Sat, 15 Jan 2022 18:00:11 +0000
Subject: [PATCH] Fix an edge case for cell connectivity

---
 game/src/ltn/auto.rs |  4 ++--
 game/src/ltn/mod.rs  | 15 +++++++++------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/game/src/ltn/auto.rs b/game/src/ltn/auto.rs
index 574310337b..9c70173c0b 100644
--- a/game/src/ltn/auto.rs
+++ b/game/src/ltn/auto.rs
@@ -139,14 +139,14 @@ fn only_one_border(app: &mut App, neighborhood: &Neighborhood) {
                             .modal_filters
                             .roads
                             .insert(road.id, 0.1 * road.length());
+                        break;
                     } else if road.dst_i == *i {
                         app.session
                             .modal_filters
                             .roads
                             .insert(road.id, 0.9 * road.length());
+                        break;
                     }
-                    // Sometimes a cell has multiple roads connecing to the same border, so don't
-                    // stop looking even once we add one filter
                 }
             }
         }
diff --git a/game/src/ltn/mod.rs b/game/src/ltn/mod.rs
index a5280f66e9..8df0568b68 100644
--- a/game/src/ltn/mod.rs
+++ b/game/src/ltn/mod.rs
@@ -270,14 +270,17 @@ fn floodfill(
             },
         );
         for i in [current.src_i, current.dst_i] {
+            // It's possible for one border intersection to have two roads in the interior of the
+            // neighborhood. Don't consider a turn between those roads through this intersection as
+            // counting as connectivity -- we're right at the boundary road, so it's like leaving
+            // and re-entering the neighborhood.
+            if neighborhood_borders.contains(&i) {
+                cell_borders.insert(i);
+                continue;
+            }
+
             for next in &map.get_i(i).roads {
                 let next_road = map.get_r(*next);
-                if !perimeter.interior.contains(next) {
-                    if neighborhood_borders.contains(&i) {
-                        cell_borders.insert(i);
-                    }
-                    continue;
-                }
                 if let Some(filter) = modal_filters.intersections.get(&i) {
                     if !filter.allows_turn(current.id, *next) {
                         continue;