User Interface

Enabling HUDs

The current stack manager does not allow for Heads-Up-Display overlays yet, as each time a new state is pushed to the stack, the previous state is paused. We therefor have to add the possibilty to overlay states over each other:

The Stack

Overlaying States

To add a new overlay, we simply push the new state to the stack:

util::Expected<void> DirectXApp::overlayGameState(GameState* const gameState)
{
	// push new game state
	gameStates.push_back(gameState);
	if (!(*gameStates.rbegin())->initialize().wasSuccessful())
		return std::runtime_error("Critical error: Unable to shut the game state down!");

	// return success
	return { };
}

Pushing States

Now when pushing a new state to the stack, we have to pause all underlying states:

util::Expected<void> DirectXApp::pushGameState(GameState* const gameState)
{
	// pause the current state
	for (std::deque<GameState*>::reverse_iterator it = gameStates.rbegin(); it != gameStates.rend(); it++)
		if (!(*it)->pause().wasSuccessful())
			return std::runtime_error("Critical error: Unable to resume the game state");

	// push and initialize the new game state
	gameStates.push_back(gameState);
	if (!(*gameStates.rbegin())->initialize().wasSuccessful())
		return std::runtime_error("Critical error: Unable to initialize the game state!");

	// return success
	return { };
}

Popping States

When popping a state from the stack, we have to resume all underlying states:

util::Expected<void> DirectXApp::popGameState()
{
	// shut the current state down
	if (!gameStates.empty()) 
	{
		if (!(*gameStates.rbegin())->shutdown().wasSuccessful())
			return std::runtime_error("Critical error: Unable to shut the game state down!");
		gameStates.pop_back();
	}

	// resume previous states
	for (std::deque<GameState*>::reverse_iterator it = gameStates.rbegin(); it != gameStates.rend(); it++)
		if (!(*it)->resume().wasSuccessful())
			return std::runtime_error("Critical error: Unable to resume the game state");

	// return success
	return { };
}

A Barebone HUD

I created a blank HUD state that simply writes its name to the bottom of the screen. The main playState then initializes its own HUD:

util::Expected<void> PlayState::initialize()
{
    ...
    
    // initialize the game overlay
	dxApp->overlayGameState(&UI::HeadsUpDisplayState::createInstance(dxApp, L"HUD"));

	...
}

And that's it. Our Stack Manager now supports HUDs.

HUD