2 files changed, 56 insertions, 19 deletions

diff --git a/src/crepe/system/RenderSystem.cpp b/src/crepe/system/RenderSystem.cpp
index fa3d0de..96c5f27 100644
--- a/src/crepe/system/RenderSystem.cpp
+++ b/src/crepe/system/RenderSystem.cpp
@@ -1,38 +1,59 @@
+#include <algorithm>
+#include <cassert>
 #include <functional>
+#include <stdexcept>
 #include <vector>
 
 #include "../ComponentManager.h"
 #include "../api/Sprite.h"
 #include "../api/Transform.h"
 #include "../facade/SDLContext.h"
-#include "../util/Log.h"
 
 #include "RenderSystem.h"
 
 using namespace crepe;
+using namespace std;
 
-void RenderSystem::clear_screen() const { SDLContext::get_instance().clear_screen(); }
+void RenderSystem::clear_screen() { this->context.clear_screen(); }
 
-void RenderSystem::present_screen() const { SDLContext::get_instance().present_screen(); }
+void RenderSystem::present_screen() { this->context.present_screen(); }
 void RenderSystem::update_camera() {
 	ComponentManager & mgr = this->component_manager;
 
 	std::vector<std::reference_wrapper<Camera>> cameras = mgr.get_components_by_type<Camera>();
 
+	if (cameras.size() == 0) throw std::runtime_error("No cameras in current scene");
+
 	for (Camera & cam : cameras) {
-		SDLContext::get_instance().camera(cam);
-		this->curr_cam = &cam;
+		this->context.camera(cam);
+		this->curr_cam_ref = &cam;
 	}
 }
-void RenderSystem::render_sprites() const {
-	ComponentManager & mgr = this->component_manager;
 
-	std::vector<std::reference_wrapper<Sprite>> sprites = mgr.get_components_by_type<Sprite>();
+bool sorting_comparison(const Sprite & a, const Sprite & b) {
+	if (a.sorting_in_layer < b.sorting_in_layer) return true;
+	if (a.sorting_in_layer == b.sorting_in_layer) return a.order_in_layer < b.order_in_layer;
+
+	return false;
+}
+
+std::vector<std::reference_wrapper<Sprite>>
+RenderSystem::sort(std::vector<std::reference_wrapper<Sprite>> & objs) {
+
+	std::vector<std::reference_wrapper<Sprite>> sorted_objs(objs);
+	std::sort(sorted_objs.begin(), sorted_objs.end(), sorting_comparison);
+
+	return sorted_objs;
+}
+
+void RenderSystem::render_sprites() {
+	ComponentManager & mgr = this->component_manager;
+	vector<reference_wrapper<Sprite>> sprites = mgr.get_components_by_type<Sprite>();
+	vector<reference_wrapper<Sprite>> 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);
+		this->context.draw(sprite, transforms[0], *this->curr_cam_ref);
 	}
 }
 
diff --git a/src/crepe/system/RenderSystem.h b/src/crepe/system/RenderSystem.h
index 87ec494..57b9c73 100644
--- a/src/crepe/system/RenderSystem.h
+++ b/src/crepe/system/RenderSystem.h
@@ -1,18 +1,23 @@
 #pragma once
 
-#include "api/Camera.h"
+#include <functional>
+#include <vector>
+
+#include "facade/SDLContext.h"
 
 #include "System.h"
 
 namespace crepe {
 
+class Camera;
+class Sprite;
+
 /**
  * \class RenderSystem
  * \brief Manages rendering operations for all game objects.
  *
- * RenderSystem is responsible for rendering sprites, clearing and presenting the screen, and
- * managing the active camera. It functions as a singleton, providing centralized rendering
- * services for the application.
+ * RenderSystem is responsible for rendering, clearing and presenting the screen, and
+ * managing the active camera. 
  */
 class RenderSystem : public System {
 public:
@@ -25,16 +30,25 @@ public:
 
 private:
 	//! Clears the screen in preparation for rendering.
-	void clear_screen() const;
+	void clear_screen();
 
 	//! Presents the rendered frame to the display.
-	void present_screen() const;
+	void present_screen();
 
 	//! Updates the active camera used for rendering.
 	void update_camera();
 
 	//! Renders all active sprites to the screen.
-	void render_sprites() const;
+	void render_sprites();
+
+	/**
+	 * \brief sort a vector sprite objects with
+	 *
+	 * \param objs the vector that will do a sorting algorithm on 
+	 * \return returns a sorted reference vector
+	 */
+	std::vector<std::reference_wrapper<Sprite>>
+	sort(std::vector<std::reference_wrapper<Sprite>> & objs);
 
 	/**
 	 * \todo Include color handling for sprites.
@@ -48,8 +62,10 @@ private:
 
 private:
 	//! Pointer to the current active camera for rendering
-	Camera * curr_cam = nullptr;
+	Camera * curr_cam_ref = nullptr;
 	// TODO: needs a better solution
+
+	SDLContext & context = SDLContext::get_instance();
 };
 
 } // namespace crepe