MyGUI and Game States

The game I am working on has several different "states" (as part of a Finite State Automaton). Transitions between states are controlled via a Game Manager whose internal structure is simply a stack. For example, pressing "Play" in the MenuState would pop a PlayState on the stack. Anyway, I am having trouble integrating MyGUI into this architecture.

When I was using QuickGUI, I basically created a new QuickGUIManager in each state I wanted to display GUI components. However, this idea doesn't work well with MyGUI.

In my MenuState, this is how I initialize GUI:
mPlatform = new MyGUI::OgrePlatform();
mPlatform->initialise(mRoot->getAutoCreatedWindow(), mSceneMgr, "General", getWriteDir()+"\\MyGUI.log");
mGUI = new MyGUI::Gui();
mGUI->initialise("core.xml",getWriteDir()+"\\MyGUI.log");

Adding the above code to the PlayState does not work. I have tried this approach for PlayState:
MyGUI::OgreRenderManager * renderManager = MyGUI::OgreRenderManager::getInstancePtr();
renderManager->setRenderWindow(mWindow);
renderManager->setSceneManager(mSceneMgr);

How can I integrate MyGUI so I can have different GUI layouts loaded and displayed depending on the state? I do not want to do any manual hiding of windows. I just want to have something equivalent to having different GUI managers working so each can display its own thing whenever in its state.

Maybe you can make a Panel widget as the parent of other widgets for each gamestate , you can just hide the Panel when you change a gamestate and show the next gamestate's panel...

Maybe you can make a Panel widget as the parent of other widgets for each gamestate , you can just hide the Panel when you change a gamestate and show the next gamestate's panel...

Each game state has its own camera and viewport. Namely, the game states are truly independent from each other. I cannot simply use a MyGUI singleton unless I can change all the necessary info which I tried in my second solution above, but that doesn't work. Thanks for the suggestion though.

You should just load layouts and assign the scene manager to mygui on state creation and when changing unload the layout.
I do something like this
[Intro State]
@Startup
* tell mygui which scene manager to use (MyGUI::OgreRenderManager::getInstance().setSceneManager())
* load a layout (MyGUI::LayoutManager::getInstance().load())
* update/handle the layout as wanted while state is running

@Shutdown of the state:
* Either assign the new scene manager to mygui or temporarily set another "fake" scene manager (otherwise it may crash)
* unload the layout (MyGUI::LayoutManager::getInstance().unloadLayout())
* If there were widgets created in runtime, remove them as well
* Start the new state and do the same @Startup as with the [Intro State]

I'm sure there are better ways to handle this (I'm a bloody noob), but I hope this helps.

You should just load layouts and assign the scene manager to mygui on state creation and when changing unload the layout.
I do something like this
[Intro State]
@Startup
* tell mygui which scene manager to use (MyGUI::OgreRenderManager::getInstance().setSceneManager())
* load a layout (MyGUI::LayoutManager::getInstance().load())
* update/handle the layout as wanted while state is running

@Shutdown of the state:
* Either assign the new scene manager to mygui or temporarily set another "fake" scene manager (otherwise it may crash)
* unload the layout (MyGUI::LayoutManager::getInstance().unloadLayout())
* If there were widgets created in runtime, remove them as well
* Start the new state and do the same @Startup as with the [Intro State]

I'm sure there are better ways to handle this (I'm a bloody noob), but I hope this helps.

Shmafoozius,

Many thanks for that! Your solution works well. However, like you said, a temporary scene manager must be set or else it crashes. Is there a way to get around that? The way it is being handled right now, the MainMenuState is never destroyed and its SceneManager is publicly available as a temporary placeholder between states. However, this looks bad and I would like to avoid it.

How do I create a "fake" scene manager which lives even after a state is destroyed but before the other state sets its own scene manager?

You can use nullptr instead of fake scene manager, so set no scene manager.
MyGUI::OgreRenderManager::getInstance().setSceneManager(nullprt);