Adds instructions to readme

[rbdr/super-polarity] / SuperPolarity / ScreenManager.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace SuperPolarity
{
    static class ScreenManager
    {
        static Stack<Screen> Screens;
        static SuperPolarity Game;

        static ScreenManager()
        {
            Screens = new Stack<Screen>();
        }

        static public void Push(Screen screen)
        {
            if (Screens.Count > 0)
            {
                Screens.Peek().Active = false;
            }

            screen.LoadContent();
            screen.Active = true;
            Screens.Push(screen);
        }

        static public void Pop()
        {
            var screen = Screens.Pop();
            screen.Active = false;
            screen.CleanUp();
            Screens.Peek().Active = true;
        }

        static public void Update(GameTime gameTime)
        {
            Screens.Peek().Update(gameTime);
        }

        static public void Draw(SpriteBatch spriteBatch)
        {
            Screens.Peek().Draw(spriteBatch);
        }

        internal static void SetGame(SuperPolarity game)
        {
            Game = game;
        }
    }
}