Exit vaults, level type

lib/world/level.dart

@@ -1,3 +1,23 @@
+import 'package:dartterm/bitmap.dart';
+import 'package:dartterm/algorithms/geometry.dart' as geo;
+
 class Level {
-  Set<(int, int)> openCells = {};
+  Bitmap<LevelTile> tiles;
+  geo.Offset spawn;
+
+  geo.Size get size => tiles.size;
+
+  Level(this.tiles, this.spawn) {
+    assert(tiles.rect.containsPoint(spawn));
+  }
+}
+
+enum LevelTile {
+  exit,
+
+  floor,
+  wall,
+
+  closedDoor,
+  openDoor,
 }