Add a helper scene_base & inherit app from it

libs/app/include/psemek/app/app.hpp

@@ -10,7 +10,7 @@ namespace psemek::app
 {
 
 	struct app
-		: scene
+		: scene_base
 	{
 		app(std::string const & name);
 		app(std::string const & name, int multisampling);
@@ -18,9 +18,9 @@ namespace psemek::app
 
 		virtual bool running() const;
 		virtual void stop();
+		virtual void on_quit();
 
 		void on_resize(int width, int height) override;
-		virtual void on_quit();
 
 		void render() override;
 

libs/app/include/psemek/app/scene.hpp

@@ -1,7 +1,12 @@
 #pragma once
 
+#include <psemek/geom/point.hpp>
+
 #include <SDL2/SDL_keycode.h>
 
+#include <optional>
+#include <set>
+
 namespace psemek::app
 {
 
@@ -34,4 +39,35 @@ namespace psemek::app
 
 	inline scene::~scene() = default;
 
+	struct scene_base
+		: scene
+	{
+		void on_mouse_move(int x, int y, int, int) override { mouse_ = geom::point{x, y}; }
+		void on_left_button_down() override { left_button_down_ = true; }
+		void on_left_button_up() override { left_button_down_ = false; }
+		void on_middle_button_down() override { middle_button_down_ = true; }
+		void on_middle_button_up() override { middle_button_down_ = false; }
+		void on_right_button_down() override { right_button_down_ = true; }
+		void on_right_button_up() override { right_button_down_ = false; }
+		void on_key_down(SDL_Keycode key) override { keys_.insert(key); }
+		void on_key_up(SDL_Keycode key) override { keys_.erase(key); }
+
+		bool is_left_button_down() const { return left_button_down_; }
+		bool is_middle_button_down() const { return middle_button_down_; }
+		bool is_right_button_down() const { return right_button_down_; }
+
+		std::optional<geom::point<int, 2>> mouse() const { return mouse_; }
+
+		bool is_key_down(SDL_Keycode key) const { return keys_.count(key) > 0; }
+
+	private:
+		bool left_button_down_ = false;
+		bool middle_button_down_ = false;
+		bool right_button_down_ = false;
+
+		std::optional<geom::point<int, 2>> mouse_;
+
+		std::set<SDL_Keycode> keys_;
+	};
+
 }