2 files changed, 37 insertions, 6 deletions

diff --git a/src/crepe/system/RenderSystem.cpp b/src/crepe/system/RenderSystem.cpp
index 10211a3..718036c 100644
--- a/src/crepe/system/RenderSystem.cpp
+++ b/src/crepe/system/RenderSystem.cpp
@@ -1,3 +1,5 @@
+#include <algorithm>
+#include <cassert>
 #include <functional>
 #include <vector>
 
@@ -6,6 +8,7 @@
 #include "../api/Transform.h"
 #include "../facade/SDLContext.h"
 #include "../util/log.h"
+#include "Asset.h"
 
 #include "RenderSystem.h"
 
@@ -29,7 +32,6 @@ void RenderSystem::present_screen() const {
 }
 void RenderSystem::update_camera() {
 	ComponentManager & mgr = ComponentManager::get_instance();
-
 	std::vector<std::reference_wrapper<Camera>> cameras
 		= mgr.get_components_by_type<Camera>();
 
@@ -38,15 +40,38 @@ void RenderSystem::update_camera() {
 		this->curr_cam = &cam;
 	}
 }
-void RenderSystem::render_sprites() const {
+
+std::vector<std::reference_wrapper<Sprite>>
+RenderSystem::sort(std::vector<std::reference_wrapper<Sprite>> & objs) {
+	if (objs.empty()) return {};
+
+	std::vector<std::reference_wrapper<Sprite>> sorted_objs;
+	sorted_objs.insert(sorted_objs.end(), objs.begin(), objs.end());
+	assert(sorted_objs.size() != objs.size());
+
+	std::sort(sorted_objs.begin(), sorted_objs.end(),
+			  [](const std::reference_wrapper<Sprite> & a,
+				 const std::reference_wrapper<Sprite> & b) {
+				  const Sprite & sprite_a = a.get();
+				  const Sprite & sprite_b = b.get();
+				  if (sprite_a.sorting_in_layer == sprite_b.sorting_in_layer) {
+					  return sprite_a.order_in_layer < sprite_b.order_in_layer;
+				  }
+				  return sprite_a.sorting_in_layer < sprite_b.sorting_in_layer;
+			  });
+	return sorted_objs;
+}
+
+void RenderSystem::render_sprites() {
 
 	ComponentManager & mgr = ComponentManager::get_instance();
 
-	std::vector<std::reference_wrapper<Sprite>> sprites
-		= mgr.get_components_by_type<Sprite>();
+	auto sprites = mgr.get_components_by_type<Sprite>();
 
+	auto sorted_sprites = this->sort(sprites);
+	
 	SDLContext & render = SDLContext::get_instance();
-	for (const Sprite & sprite : sprites) {
+	for (const Sprite & sprite : sorted_sprites) {
 		auto transforms
 			= mgr.get_components_by_id<Transform>(sprite.game_object_id);
 		render.draw(sprite, transforms[0], *curr_cam);
diff --git a/src/crepe/system/RenderSystem.h b/src/crepe/system/RenderSystem.h
index 70db21a..a83633a 100644
--- a/src/crepe/system/RenderSystem.h
+++ b/src/crepe/system/RenderSystem.h
@@ -3,6 +3,9 @@
 #include "api/Camera.h"
 
 #include "System.h"
+#include "api/Sprite.h"
+#include <functional>
+#include <vector>
 
 namespace crepe {
 
@@ -44,7 +47,10 @@ private:
 	void update_camera();
 
 	//! Renders all active sprites to the screen.
-	void render_sprites() const;
+	void render_sprites() ;
+
+	std::vector<std::reference_wrapper<Sprite>>
+	sort(std::vector<std::reference_wrapper<Sprite>> & objs);
 
 	/**
 	 * \todo Include color handling for sprites.