public void AddScreen(GameScreen screen)
 {
     transition = true;
     newScreen = screen;
     fade.IsActive = true;
     fade.Alpha = 0.0f;
     fade.ActivateValue = 1.0f;
 }
        private void Transition(GameTime gameTime)
        {
            fade.Update(gameTime);
            if(fade.Alpha == 1.0f && fade.Timer.TotalSeconds == 1.0f)
            {
                screenStack.Push(newScreen);
                currentScreen.UnloadContent();
                currentScreen = newScreen;
                currentScreen.LoadContent(content);

            }
            else if (fade.Alpha == 0.0f)
            {
                transition = false;
                fade.IsActive = false;
            }
        }
 public void Initialize()
 {
     currentScreen = new SplashScreen();
     fade = new FadeAnimation();
 }