diff --git a/assets/tiles.json b/assets/tiles.json
index d657b7b..3b6c226 100644
--- a/assets/tiles.json
+++ b/assets/tiles.json
@@ -4,27 +4,31 @@
     "foreground": [40, 15, 125],
     "background": [200, 15, 75],
     "collision": false,
-    "display": 10398
+    "display": 10398,
+    "id": 0
   },
   "WALL_MOSS": {
     "texture": "assets/glowing_moss_wall-256.png",
     "foreground": [230, 20, 30],
     "background": [230, 20, 120],
     "collision": true,
-    "display": 8820
+    "display": 8820,
+    "id": 1
   },
   "WALL_PLAIN": {
     "texture": "assets/wall_texture_test-256.png",
     "foreground": [230, 20, 30],
     "background": [230, 20, 120],
     "collision": true,
-    "display": 9608
+    "display": 9608,
+    "id": 2
   },
   "WALL_VINES": {
     "texture": "assets/wall_with_vines-256.png",
     "foreground": [230, 20, 30],
     "background": [230, 20, 120],
     "collision": false,
-    "display": 35
+    "display": 35,
+    "id": 3
   }
 }
diff --git a/map.cpp b/map.cpp
index d008941..e2dbfc5 100644
--- a/map.cpp
+++ b/map.cpp
@@ -149,6 +149,7 @@ void Map::load_tiles() {
 }
 
 void Map::enclose() {
+  // wraps the outside edge with solid walls
   std::array<Point, 4> starts{{
     {0,0}, {$width-1, 0}, {$width-1, $height-1}, {0, $height-1}
   }};
diff --git a/raycaster.cpp b/raycaster.cpp
index 16b04e4..055f4f6 100644
--- a/raycaster.cpp
+++ b/raycaster.cpp
@@ -383,6 +383,8 @@ void Raycaster::draw_ceiling_floor() {
       int map_y = int(floor_y);
       int light_level = matrix::inbounds(lights, map_x, map_y) ? lights[map_y][map_x] : 30;
 
+      // NOTE: use map_x/y to get the floor, ceiling texture.
+
       // FLOOR
       color = $floor_texture[texture_width * ty + tx];
       $pixels[pixcoord(x, y)] = lighting_calc(color, row_distance, light_level);
diff --git a/tilemap.cpp b/tilemap.cpp
index 94ae667..80b0879 100644
--- a/tilemap.cpp
+++ b/tilemap.cpp
@@ -38,8 +38,8 @@ void TileMap::dump(int show_x, int show_y) {
   std::cout << to_string(show_x, show_y) << std::endl;
 }
 
-void TileMap::set_tile(size_t x, size_t y, string tile_name) {
-  json tile_conf = $config[tile_name];
+void TileMap::set_tile(size_t x, size_t y, const string& tile_name) {
+  json& tile_conf = $config[tile_name];
 
   auto tile = components::convert<Tile>(tile_conf);
   $tile_ids[y][x] = tile.display;
diff --git a/tilemap.hpp b/tilemap.hpp
index e8312c6..b450da4 100644
--- a/tilemap.hpp
+++ b/tilemap.hpp
@@ -28,8 +28,8 @@ public:
   size_t width() { return $width; }
   size_t height() { return $height; }
   void load(matrix::Matrix &walls);
-  const components::Tile &at(size_t x, size_t y);
-  void set_tile(size_t x, size_t y, std::string tile_name);
+  const components::Tile& at(size_t x, size_t y);
+  void set_tile(size_t x, size_t y, const std::string& tile_name);
   std::vector<std::string> tile_names(bool collision);
 
   std::string to_string(int show_x, int show_y);