From 8f64c95dbd4b69cbb85313e2e514cf068f376b20 Mon Sep 17 00:00:00 2001
From: Derek Christ <christ.derek@gmail.com>
Date: Sat, 24 May 2025 21:25:48 +0200
Subject: [PATCH] Draw background as sprite

---
 main.cpp   | 52 ++++++++++++++++++++++++++++------------------------
 sprite.hpp |  2 ++
 util.hpp   |  6 ++++++
 3 files changed, 36 insertions(+), 24 deletions(-)
 create mode 100644 util.hpp

diff --git a/main.cpp b/main.cpp
index dd6edb9..c54724e 100644
--- a/main.cpp
+++ b/main.cpp
@@ -46,6 +46,13 @@ int main() {
   init_assets(world);
   auto *texture_assets = world.get<TextureAssets>();
 
+  world.entity("Background")
+      .set<Position>(Position{.x = 0, .y = 0})
+      .set<Sprite>(
+          Sprite{.texture = &texture_assets->background,
+                 .texture_atlas_index = 0,
+                 .custom_size = Vec2{.x = WINDOW_WIDTH, .y = WINDOW_HEIGHT}});
+
   world.entity("Sprite1")
       .set<Position>(Position{.x = 0, .y = 0})
       .set<Sprite>(
@@ -56,30 +63,29 @@ int main() {
       .set<Sprite>(
           Sprite{.texture = &texture_assets->fruits, .texture_atlas_index = 5});
 
-  flecs::system sys =
-      world
-          .system<SdlHandles const, Position const, Sprite const>(
-              "RenderSprites")
-          .term_at(0)
-          .singleton()
-          .each([](flecs::entity e, SdlHandles const &sdl_handles,
-                   Position const &pos, Sprite const &sprite) {
-            TextureAtlasLayout layout = sprite.texture->texture_atlas_layout;
-            uint8_t row = sprite.texture_atlas_index / layout.columns;
-            uint8_t column = sprite.texture_atlas_index % layout.columns;
-            SDL_FRect srcrect{static_cast<float>(column * layout.width),
-                              static_cast<float>(row * layout.height),
-                              static_cast<float>(layout.width),
-                              static_cast<float>(layout.height)};
+  world.system<SdlHandles const, Position const, Sprite const>("RenderSprites")
+      .term_at(0)
+      .singleton()
+      .each([](flecs::entity e, SdlHandles const &sdl_handles,
+               Position const &pos, Sprite const &sprite) {
+        TextureAtlasLayout layout = sprite.texture->texture_atlas_layout;
+        uint8_t row = sprite.texture_atlas_index / layout.columns;
+        uint8_t column = sprite.texture_atlas_index % layout.columns;
+        SDL_FRect srcrect{static_cast<float>(column * layout.width),
+                          static_cast<float>(row * layout.height),
+                          static_cast<float>(layout.width),
+                          static_cast<float>(layout.height)};
 
-            SDL_FRect dstrect{static_cast<float>(pos.x),
-                              static_cast<float>(pos.y),
-                              static_cast<float>(layout.width),
-                              static_cast<float>(layout.height)};
+        Vec2 size = sprite.custom_size.value_or(
+            {.x = layout.width, .y = layout.height});
 
-            SDL_RenderTexture(sdl_handles.renderer, sprite.texture->sdl_texture,
-                              &srcrect, &dstrect);
-          });
+        SDL_FRect dstrect{static_cast<float>(pos.x), static_cast<float>(pos.y),
+                          static_cast<float>(size.x),
+                          static_cast<float>(size.y)};
+
+        SDL_RenderTexture(sdl_handles.renderer, sprite.texture->sdl_texture,
+                          &srcrect, &dstrect);
+      });
 
   bool exit_gameloop = false;
   while (!exit_gameloop) {
@@ -121,8 +127,6 @@ int main() {
 
     // Render
     SDL_RenderClear(renderer);
-    SDL_RenderTexture(renderer, texture_assets->background.sdl_texture, nullptr,
-                      nullptr);
     world.progress();
     SDL_RenderPresent(renderer);
   }
diff --git a/sprite.hpp b/sprite.hpp
index 1ef7dfd..46ec70d 100644
--- a/sprite.hpp
+++ b/sprite.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "assets.hpp"
+#include "util.hpp"
 
 #include <SDL3/SDL.h>
 #include <cstdint>
@@ -9,4 +10,5 @@
 struct Sprite {
   Texture const *texture;
   uint16_t texture_atlas_index;
+  std::optional<Vec2> custom_size;
 };
diff --git a/util.hpp b/util.hpp
new file mode 100644
index 0000000..1bff1bd
--- /dev/null
+++ b/util.hpp
@@ -0,0 +1,6 @@
+#pragma once
+
+struct Vec2 {
+  int x;
+  int y;
+};