atomises rooms and corridors

- room sorter
- rounding room corners
- dogleg and bsp corridors
- room exploder

src/map_builders/room_corner_rounding.rs

@@ -0,0 +1,57 @@
+use super::{BuilderMap, MetaMapBuilder, Rect, TileType};
+use rltk::RandomNumberGenerator;
+
+pub struct RoomCornerRounder {}
+
+impl MetaMapBuilder for RoomCornerRounder {
+    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data: &mut BuilderMap) {
+        self.build(rng, build_data);
+    }
+}
+
+impl RoomCornerRounder {
+    #[allow(dead_code)]
+    pub fn new() -> Box<RoomCornerRounder> {
+        return Box::new(RoomCornerRounder {});
+    }
+
+    fn fill_if_corner(&mut self, x: i32, y: i32, build_data: &mut BuilderMap) {
+        let w = build_data.map.width;
+        let h = build_data.map.height;
+        let idx = build_data.map.xy_idx(x, y);
+        let mut neighbour_walls = 0;
+        if x > 0 && build_data.map.tiles[idx - 1] == TileType::Wall {
+            neighbour_walls += 1;
+        }
+        if y > 0 && build_data.map.tiles[idx - w as usize] == TileType::Wall {
+            neighbour_walls += 1;
+        }
+        if x < w - 2 && build_data.map.tiles[idx + 1] == TileType::Wall {
+            neighbour_walls += 1;
+        }
+        if y < h - 2 && build_data.map.tiles[idx + w as usize] == TileType::Wall {
+            neighbour_walls += 1;
+        }
+        if neighbour_walls == 2 {
+            build_data.map.tiles[idx] = TileType::Wall;
+        }
+    }
+
+    fn build(&mut self, _rng: &mut RandomNumberGenerator, build_data: &mut BuilderMap) {
+        let rooms: Vec<Rect>;
+        if let Some(rooms_builder) = &build_data.rooms {
+            rooms = rooms_builder.clone();
+        } else {
+            panic!("RoomCornerRounding requires a builder with rooms.");
+        }
+
+        for room in rooms.iter() {
+            self.fill_if_corner(room.x1 + 1, room.y1 + 1, build_data);
+            self.fill_if_corner(room.x2, room.y1 + 1, build_data);
+            self.fill_if_corner(room.x1 + 1, room.y2, build_data);
+            self.fill_if_corner(room.x2, room.y2, build_data);
+
+            build_data.take_snapshot();
+        }
+    }
+}