/MonocleEngine/Engine.cs

using System;

using System.Collections.Generic;

using System.Linq;

using Microsoft.Xna.Framework;

using Microsoft.Xna.Framework.Audio;

using Microsoft.Xna.Framework.Content;

using Microsoft.Xna.Framework.GamerServices;

using Microsoft.Xna.Framework.Graphics;

using Microsoft.Xna.Framework.Input;

using Microsoft.Xna.Framework.Media;



namespace Monocle

{

    public enum GameTags { Player = 0, Corpse, Solid, Actor, Arrow, Target, PlayerCollider, Coin, Orb, LightSource, Enemy, Pickup, Climbable, HUD, OWLocation };



    public class Engine : Game

    {

        static public Engine Instance { get; private set; }

        static internal int TagAmount = Enum.GetNames(typeof(GameTags)).Length;



        public GraphicsDeviceManager Graphics { get; private set; }

        public Screen Screen { get; private set; }

        public float DeltaTime { get; private set; }



        private Scene scene;

        private Scene nextScene;

        private string windowTitle;

        private float framesPerSecond;

        private float changeFPSTo;

        private int fpsChangeDelay;



#if DEBUG

        public Commands Commands { get; private set; }

        private TimeSpan counterElapsed = TimeSpan.Zero;

        private int counterFrames = 0;

#endif



        public Engine(int width, int height, float framesPerSecond, string windowTitle)

        {

            this.windowTitle = windowTitle;



            Instance = this;

            Graphics = new GraphicsDeviceManager(this);

            Content.RootDirectory = "Content";

            IsMouseVisible = true;

            Screen = new Screen(this, width, height);



            IsFixedTimeStep = true;

            FramesPerSecond = framesPerSecond;

        }



        public float FramesPerSecond

        {

            get { return framesPerSecond; }

            set

            {

                if (framesPerSecond != value)

                {

                    framesPerSecond = value;

                    TargetElapsedTime = TimeSpan.FromMilliseconds(Math.Floor(1000.0 / (double)framesPerSecond));

                    DeltaTime = 1.0f / framesPerSecond;

                    fpsChangeDelay = 0;

                }

            }

        }



        protected override void Initialize()

        {

            base.Initialize();



#if DEBUG

            Commands = new Commands();

#endif



            Input.Initialize();

            Screen.Initialize();

            Monocle.Draw.Init(GraphicsDevice);

            Graphics.DeviceReset += OnGraphicsReset;



            Window.Title = windowTitle;

        }



        private void OnGraphicsReset(object sender, EventArgs e)

        {

            if (scene != null)

                scene.HandleGraphicsReset();

            if (nextScene != null)

                nextScene.HandleGraphicsReset();

        }



        protected override void Update(GameTime gameTime)

        {

#if DEBUG

            //In Debug mode, press Left Shift + ESC to quit the game

            if (Input.Pressed(Keys.Escape) && Input.Check(Keys.LeftShift))

                this.Exit();



            if (Commands.Open)

            {

                Commands.UpdateOpen();

                Input.UpdateNoKeyboard();

            }

            else

            {

                Commands.UpdateClosed();

                Input.Update();

            }

#else

            Input.Update();

#endif            

 

            //FPS change counter

            if (fpsChangeDelay > 0)

            {

                fpsChangeDelay--;

                if (fpsChangeDelay == 0)

                    FramesPerSecond = changeFPSTo;

            }



            if (scene != null && scene.Active)

                scene.Update();



            if (scene != nextScene)

            {

                if (scene != null)

                    scene.End();

                CancelChangeFPS();

                scene = nextScene;

                if (scene != null)

                    scene.Begin();

            }



            base.Update(gameTime);

        }



        protected override void Draw(GameTime gameTime)

        {

            GraphicsDevice.SetRenderTarget(Screen.RenderTarget);

            GraphicsDevice.Clear(Screen.ClearColor);



            if (scene != null)

                scene.Render();



            GraphicsDevice.SetRenderTarget(null);

            GraphicsDevice.Clear(Color.Black);

            Screen.Render();



            base.Draw(gameTime);



#if DEBUG

            if (Commands.Open)

                Commands.Render();



            //Frame counter

            counterFrames++;

            counterElapsed += gameTime.ElapsedGameTime;

            if (counterElapsed > TimeSpan.FromSeconds(1))

            {

                Window.Title = windowTitle + " " + counterFrames.ToString() + " fps";

                counterFrames = 0;

                counterElapsed -= TimeSpan.FromSeconds(1);

            }

#endif

        }



        public Scene Scene

        {

            get { return scene; }

            set { nextScene = value; }

        }



        #region Change the FPS



        public void ChangeFPS(float newFPS, int frameDelay)

        {

            if (newFPS != framesPerSecond)

            {

                changeFPSTo = newFPS;

                fpsChangeDelay = frameDelay;

            }

        }



        public void CancelChangeFPS()

        {

            fpsChangeDelay = 0;

        }



        #endregion

    }

}