Give MultiViewportControllerInstances a pointer to their parent controller, to allow state management

Code/Framework/AzFramework/AzFramework/Viewport/MultiViewportController.h

@@ -48,21 +48,28 @@ namespace AzFramework
     };
 
     //! The interface used by MultiViewportController to manage individual instances.
+    template <class TController>
     class MultiViewportControllerInstanceInterface
     {
     public:
-        explicit MultiViewportControllerInstanceInterface(ViewportId viewport)
+        using ControllerType = TController;
+
+        explicit MultiViewportControllerInstanceInterface(ViewportId viewport, TController* controller)
             : m_viewportId(viewport)
+            , m_controller(controller)
         {
         }
 
         ViewportId GetViewportId() const { return m_viewportId; }
+        TController* GetController() { return m_controller; }
+        const TController* GetController() const { return m_controller; }
 
         virtual bool HandleInputChannelEvent([[maybe_unused]]const ViewportControllerInputEvent& event) { return false; }
         virtual void ResetInputChannels() {}
         virtual void UpdateViewport([[maybe_unused]]const ViewportControllerUpdateEvent& event) {}
 
     private:
+        TController* m_controller;
         ViewportId m_viewportId;
     };
 } //namespace AzFramework

Code/Framework/AzFramework/AzFramework/Viewport/MultiViewportController.inl

@@ -17,8 +17,8 @@ namespace AzFramework
     MultiViewportController<TViewportControllerInstance, Priority>::~MultiViewportController()
     {
         static_assert(
-            AZStd::is_constructible<TViewportControllerInstance, ViewportId>::value,
-            "TViewportControllerInstance must implement a TViewportControllerInstance(ViewportId) constructor"
+            AZStd::is_same<TViewportControllerInstance, decltype(TViewportControllerInstance(0, nullptr))>::value,
+            "TViewportControllerInstance must implement a TViewportControllerInstance(ViewportId, ViewportController) constructor"
         );
     }
 
@@ -50,7 +50,7 @@ namespace AzFramework
     template <class TViewportControllerInstance, ViewportControllerPriority Priority>
     void MultiViewportController<TViewportControllerInstance, Priority>::RegisterViewportContext(ViewportId viewport)
     {
-        m_instances[viewport] = AZStd::make_unique<TViewportControllerInstance>(viewport);
+        m_instances[viewport] = AZStd::make_unique<TViewportControllerInstance>(viewport, static_cast<TViewportControllerInstance::ControllerType*>(this));
     }
 
     template <class TViewportControllerInstance, ViewportControllerPriority Priority>