From 6bf4635f12de6fd1652acb6dbdc06e0353764a06 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Fri, 1 Aug 2025 17:03:39 +0200
Subject: [PATCH] ru:: bfs

---
 rogueviz/ru/classes.cpp |  3 +++
 rogueviz/ru/room.cpp    | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/rogueviz/ru/classes.cpp b/rogueviz/ru/classes.cpp
index 90392569..b2fbba52 100644
--- a/rogueviz/ru/classes.cpp
+++ b/rogueviz/ru/classes.cpp
@@ -163,6 +163,9 @@ struct room {
   void fov_from(int sx, int sy);
 
   void create_texture();
+
+  using bfs_progress = hr::function<bool(intxy)>;
+  vector<intxy> bfs(intxy start, const bfs_progress& f);
   };
 
 struct xy {
diff --git a/rogueviz/ru/room.cpp b/rogueviz/ru/room.cpp
index ffa8b9c0..779dbb26 100644
--- a/rogueviz/ru/room.cpp
+++ b/rogueviz/ru/room.cpp
@@ -127,6 +127,28 @@ void room::fov_from(int sx, int sy) {
       }
     }
   }
+
+array<array<int, room_x>, room_y> bfs_visited;
+int bfs_id;
+
+vector<intxy> room::bfs(intxy start, const bfs_progress& f) {
+  bfs_id++;
+  vector<intxy> all = { start };
+  for(int i=0; i<isize(all); i++) {
+    auto at = all[i];
+    auto add = [&] (int x, int y) {
+      if(bfs_visited[y][x] == bfs_id) return;
+      bfs_visited[y][x] = bfs_id;
+      intxy v {x, y};
+      if(f(v)) all.push_back(v);
+      };
+    if(at.x > 0) add(at.x-1, at.y);
+    if(at.x < room_x-1) add(at.x+1, at.y);
+    if(at.y > 0) add(at.x, at.y-1);
+    if(at.y < room_y-1) add(at.x, at.y+1);
+    }
+  return all;
+  }
     
 room *get_room_at(cell *c) {
   bool create = !rooms.count(c);