layer transition with temporary testing code until the event system is implemented

SakuraCore/src/Application.h

@@ -99,4 +99,6 @@ private:
     SakuraVNE::ImGuiInit *m_ImGui;
 
     static Application *s_Instance;
+
+    friend class SakuraVNE::Layer;
 };

SakuraCore/src/Layer.cpp

@@ -1,6 +1,19 @@
 #include "Layer.h"
+#include "Application.h"
+#include <memory>
 #include <string>
 
 namespace SakuraVNE {
 Layer::Layer(const std::string &name, bool isActive) : m_LayerName(name), m_isActive(isActive) {}
+
+void Layer::QueueTransition(std::unique_ptr<Layer> toLayer) {
+    // TODO: redo this based on the event video
+    auto &layerStack = Application::Get().m_LayerStack;
+    for (auto &layer : layerStack) {
+        if (layer.get() == this) {
+            layer = std::move(toLayer);
+            return;
+        }
+    }
+}
 } // namespace SakuraVNE

SakuraCore/src/Layer.h

@@ -1,6 +1,8 @@
 #pragma once
 
 #include "SDL3/SDL_stdinc.h"
+#include <concepts>
+#include <memory>
 #include <string>
 
 namespace SakuraVNE {
@@ -14,14 +16,18 @@ public:
     virtual void OnAttach() {}
     virtual void OnDetach() {}
     virtual void OnImGuiRender() {}
-    virtual void TransitionTo() {}
-    virtual void Suspend() {}
-    virtual void Activate() {}
+    virtual void Suspend() { m_isActive = false; }
+    virtual void Activate() { m_isActive = true; }
+
+    template <std::derived_from<Layer> T, typename... Args> void TransitionTo(Args &&...args) { QueueTransition(std::move(std::make_unique<T>(std::forward<Args>(args)...))); }
 
     const std::string &GetName() const { return m_LayerName; }
 
 protected:
     std::string m_LayerName;
     bool m_isActive = true;
+
+private:
+    void QueueTransition(std::unique_ptr<Layer> layer);
 };
 } // namespace SakuraVNE