I can now create any tiles I want. First version is just one room will have a circular pool in it.

tilemap.cpp

@@ -30,10 +30,7 @@ void TileMap::dump(int show_x, int show_y) {
   }
 }
 
-void TileMap::load(matrix::Matrix &walls) {
-  for(matrix::each_cell it{walls}; it.next();) {
-    string tile_name = walls[it.y][it.x] == SPACE_VALUE ? "FLOOR_TILE" : "WALL_TILE";
-
+void TileMap::set_tile(size_t x, size_t y, string tile_name) {
     std::wstring tile_id = $config.wstring(tile_name, "display");
     json tile_conf = $config[tile_name];
     TileCell tile{
@@ -45,8 +42,14 @@ void TileMap::load(matrix::Matrix &walls) {
         tile_conf["background"][1],
         tile_conf["background"][2]};
 
-    $tile_ids[it.y][it.x] = tile_id[0];
-    $display[it.y][it.x] = tile;
+    $tile_ids[y][x] = tile_id[0];
+    $display[y][x] = tile;
+}
+
+void TileMap::load(matrix::Matrix &walls) {
+  for(matrix::each_cell it{walls}; it.next();) {
+    string tile_name = walls[it.y][it.x] == SPACE_VALUE ? "FLOOR_TILE" : "WALL_TILE";
+    set_tile(it.x, it.y, tile_name);
   }
 }
 

tilemap.hpp

@@ -39,6 +39,7 @@ public:
   size_t height() { return $height; }
   void load(matrix::Matrix &walls);
   const TileCell &at(size_t x, size_t y);
+  void set_tile(size_t x, size_t y, std::string tile_name);
 
   void dump(int show_x=-1, int show_y=-1);
   bool INVARIANT();

worldbuilder.cpp

@@ -139,8 +139,16 @@ void WorldBuilder::generate() {
     $map.$walls[it.y][it.x] = is_wall;
   }
 
-  // BUG: this is so weird
   $map.load_tiles();
+
+  Point center = $map.place_entity(1);
+  for(matrix::circle it{center, 3}; it.next();) {
+    for(int x = it.x0; x < it.x1; x++) {
+      if($map.inmap(x, it.y) && !$map.iswall(x, it.y)) {
+        $map.$tiles.set_tile(x, it.y, "WATER_TILE");
+      }
+    }
+  }
 }
 
 void WorldBuilder::make_room(size_t origin_x, size_t origin_y, size_t w, size_t h) {