I have the overlay display the low health blood using the gui system.

guecs.cpp

@@ -15,10 +15,18 @@ namespace guecs {
   }
 
   DinkyECS::Entity UI::entity(std::string name) {
+    if($name_ents.contains(name)) {
+      // already exists so just return it
+      return $name_ents.at(name);
+    } else {
       auto entity = $world.entity();
+      // this lets you look up an entity by name
+      $name_ents.insert_or_assign(name, entity);
+      // this makes it easier to get the name during querying
       $world.set<CellName>(entity, {name});
       return entity;
     }
+  }
 
   void UI::init(TexturePack& textures) {
     if($world.has_the<Background>()) {

guecs.hpp

@@ -126,6 +126,7 @@ namespace guecs {
   class UI {
     public:
       DinkyECS::World $world;
+      std::unordered_map<std::string, DinkyECS::Entity> $name_ents;
       shared_ptr<sf::Font> $font = nullptr;
       lel::Parser $parser;
       std::string $grid = "";
@@ -147,6 +148,20 @@ namespace guecs {
       void init(TexturePack& textures);
       void render(sf::RenderWindow& window);
       void mouse(float x, float y);
+
+      template <typename Comp>
+      void set(DinkyECS::Entity ent, Comp val) {
+        $world.set<Comp>(ent, val);
+      }
+
+      lel::Cell& cell_for(DinkyECS::Entity entity) {
+        return $world.get<lel::Cell>(entity);
+      }
+
+    template <typename Comp>
+      void remove(DinkyECS::Entity ent) {
+        $world.remove<Comp>(ent);
+      }
   };
 
   Clickable make_action(DinkyECS::World& target, Events::GUI event);

gui.cpp

@@ -18,7 +18,7 @@ namespace gui {
     $map_view($level),
     $combat_view($level),
     $status_view($level),
-    $overlay_view($level),
+    $overlay_view($level, $textures),
     $font{FONT_FILE_NAME},
     $text{$font},
     $rayview($textures, RAY_VIEW_WIDTH, RAY_VIEW_HEIGHT)
@@ -54,7 +54,7 @@ namespace gui {
     $rayview.position_camera($player.x + 0.5, $player.y + 0.5);
 
     $combat_view.render($textures);
-    $overlay_view.render($textures);
+    $overlay_view.render();
     $status_view.render($textures);
     $status_view.log("Welcome to the game!");
 
@@ -301,10 +301,7 @@ namespace gui {
     auto player = $level.world->get_the<Player>();
     auto player_combat = $level.world->get<Combat>(player.entity);
 
-    if(float(player_combat.hp) / float(player_combat.max_hp) < 0.5) {
-      $overlay_view.set<guecs::Sprite>("middle", {"blood_splatter"});
-      $overlay_view.$gui.init($textures);
-    }
+    $overlay_view.show_damage(float(player_combat.hp) / float(player_combat.max_hp) < 0.5);
   }
 
   void FSM::draw_gui() {

overlay_ui.cpp

@@ -6,8 +6,9 @@
 namespace gui {
   using namespace guecs;
 
-  OverlayUI::OverlayUI(GameLevel level) :
-    $level(level)
+  OverlayUI::OverlayUI(GameLevel level, TexturePack& textures) :
+    $level(level),
+    $textures(textures)
   {
     $gui.position(RAY_VIEW_X, RAY_VIEW_Y, RAY_VIEW_WIDTH, RAY_VIEW_HEIGHT);
     $gui.layout(
@@ -19,18 +20,29 @@ namespace gui {
         );
   }
 
-  void OverlayUI::render(TexturePack &textures) {
+  void OverlayUI::render() {
     auto &world = $gui.world();
     for(auto &[name, cell] : $gui.cells()) {
       auto region = $gui.entity(name);
-      $name_ents.insert_or_assign(name, region);
       world.set<lel::Cell>(region, cell);
     }
-    $gui.init(textures);
+    $gui.init($textures);
   }
 
   void OverlayUI::draw(sf::RenderWindow& window) {
     $gui.render(window);
   }
 
+  void OverlayUI::show_damage(bool show) {
+    auto middle = $gui.entity("middle");
+
+    if(show) {
+      Sprite blood{"blood_splatter"};
+      auto& cell = $gui.cell_for(middle);
+      blood.init(cell, $textures);
+      $gui.set<guecs::Sprite>(middle, blood);
+    } else {
+      $gui.remove<guecs::Sprite>(middle);
+    }
+  }
 }

overlay_ui.hpp

@@ -9,19 +9,13 @@ namespace gui {
     public:
       guecs::UI $gui;
       GameLevel $level;
-      std::unordered_map<std::string, DinkyECS::Entity> $name_ents;
+      TexturePack& $textures;
 
-      OverlayUI(GameLevel level);
+      OverlayUI(GameLevel level, TexturePack& $textures);
 
-      void render(TexturePack& texture);
+      void render();
       void draw(sf::RenderWindow& window);
       void click(int x, int y);
-
-    template <typename Comp>
-      // this should be in the GUECS really
-      void set(std::string name, Comp val) {
-        auto ent = $name_ents.at(name);
-        $level.world->set<Comp>(ent, val);
-      }
+      void show_damage(bool show);
   };
 }