SceneManager.h

#pragma once
 
#include "Assert.h"
#include "Lua/MyLua.h"
 
#include <memory>
#include <typeindex>
#include <unordered_map>
 
class Scene
{
public:
 
    virtual ~Scene()
    {
    }
 
    virtual void Update(const float deltaT) = 0;
 
    virtual void Draw() = 0;
 
    virtual void OnEnter() = 0;
 
    virtual void OnExit() = 0;
};
 
class SceneManager
{
public:
 
    void Update(const float deltaT);
 
    void Draw();
 
    template <typename T, typename... Args>
        requires std::is_base_of_v<Scene, T>
    void AddScene(Args&&... args)
    {
        auto ptr = std::make_unique<T>(std::forward<Args>(args)...);
 
        m_scenes.emplace(typeid(T), std::move(ptr));
    }
 
    template <typename T>
        requires std::is_base_of_v<Scene, T>
    void RemoveScene()
    {
        auto it = m_scenes.find(typeid(T));
        if (it != m_scenes.end())
        {
            Assert(it->second.get() != m_currentScene, "Cannot delete the current scene");
 
            m_scenes.erase(it);
        }
    }
 
    template <typename T>
        requires std::is_base_of_v<Scene, T>
    void ChangeScene()
    {
        auto it = m_scenes.find(typeid(T));
        Assert(it != m_scenes.end(), "Scene ", Demangle<T>().c_str(), " does not exist");
        Assert(it->second.get() != m_currentScene, "Cannot change to the current scene");
 
        m_nextSceneType = typeid(T);
        m_changeScene = true;
    }
 
    void ClearScenes();
 
private:
 
    void CheckForChange();
 
    Scene* m_currentScene = nullptr;
 
    bool m_changeScene = false;
    std::type_index m_nextSceneType = typeid(void);
 
    std::unordered_map<std::type_index, std::unique_ptr<Scene>> m_scenes;
};