#region File Description
//-----------------------------------------------------------------------------
// Game.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion

#region Using Statements
using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
#endregion

namespace NonPhotoRealistic
{
    /// <summary>
    /// Sample showing how to implement non-photorealistic rendering techniques,
    /// providing a cartoon shader, edge detection, and pencil sketch rendering effect.
    /// </summary>
    public class NonPhotoRealisticGame : Microsoft.Xna.Framework.Game
    {
        #region Fields


        GraphicsDeviceManager graphics;

        SpriteBatch spriteBatch;
        SpriteFont spriteFont;
        Model model;

        Random random = new Random();


        // Effect used to apply the edge detection and pencil sketch postprocessing.
        Effect postprocessEffect;


        // Overlay texture containing the pencil sketch stroke pattern.
        Texture2D sketchTexture;


        // Randomly offsets the sketch pattern to create a hand-drawn animation effect.
        Vector2 sketchJitter;
        TimeSpan timeToNextJitter;


        // Custom rendertargets.
        RenderTarget2D sceneRenderTarget;
        RenderTarget2D normalDepthRenderTarget;


        // Choose what display settings to use.
        NonPhotoRealisticSettings Settings
        {
            get { return NonPhotoRealisticSettings.PresetSettings[settingsIndex]; }
        }

        int settingsIndex = 0;


        // Current and previous input states.
        KeyboardState lastKeyboardState;
        GamePadState lastGamePadState;
        KeyboardState currentKeyboardState;
        GamePadState currentGamePadState;


        #endregion

        #region Initialization


        public NonPhotoRealisticGame()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }


        /// <summary>
        /// Load your graphics content.
        /// </summary>
        protected override void LoadContent()
        {
            spriteBatch = new SpriteBatch(graphics.GraphicsDevice);
            spriteFont = Content.Load<SpriteFont>("hudFont");
            model = Content.Load<Model>("Ship");
            postprocessEffect = Content.Load<Effect>("PostprocessEffect");
            sketchTexture = Content.Load<Texture2D>("SketchTexture");

            // Change the model to use our custom cartoon shading effect.
            Effect cartoonEffect = Content.Load<Effect>("CartoonEffect");

            ChangeEffectUsedByModel(model, cartoonEffect);

            // Create two custom rendertargets.
            PresentationParameters pp = graphics.GraphicsDevice.PresentationParameters;

            sceneRenderTarget = new RenderTarget2D(graphics.GraphicsDevice,
                                                   pp.BackBufferWidth, pp.BackBufferHeight, false,
                                                   pp.BackBufferFormat, pp.DepthStencilFormat);

            normalDepthRenderTarget = new RenderTarget2D(graphics.GraphicsDevice,
                                                         pp.BackBufferWidth, pp.BackBufferHeight, false,
                                                         pp.BackBufferFormat, pp.DepthStencilFormat);
        }


        /// <summary>
        /// Unload your graphics content.
        /// </summary>
        protected override void UnloadContent()
        {
            if (sceneRenderTarget != null)
            {
                sceneRenderTarget.Dispose();
                sceneRenderTarget = null;
            }

            if (normalDepthRenderTarget != null)
            {
                normalDepthRenderTarget.Dispose();
                normalDepthRenderTarget = null;
            }
        }


        /// <summary>
        /// Alters a model so it will draw using a custom effect, while preserving
        /// whatever textures were set on it as part of the original effects.
        /// </summary>
        static void ChangeEffectUsedByModel(Model model, Effect replacementEffect)
        {
            // Table mapping the original effects to our replacement versions.
            Dictionary<Effect, Effect> effectMapping = new Dictionary<Effect, Effect>();

            foreach (ModelMesh mesh in model.Meshes)
            {
                // Scan over all the effects currently on the mesh.
                foreach (BasicEffect oldEffect in mesh.Effects)
                {
                    // If we haven't already seen this effect...
                    if (!effectMapping.ContainsKey(oldEffect))
                    {
                        // Make a clone of our replacement effect. We can't just use
                        // it directly, because the same effect might need to be
                        // applied several times to different parts of the model using
                        // a different texture each time, so we need a fresh copy each
                        // time we want to set a different texture into it.
                        Effect newEffect = replacementEffect.Clone();

                        // Copy across the texture from the original effect.
                        newEffect.Parameters["Texture"].SetValue(oldEffect.Texture);
                        newEffect.Parameters["TextureEnabled"].SetValue(oldEffect.TextureEnabled);

                        effectMapping.Add(oldEffect, newEffect);
                    }
                }

                // Now that we've found all the effects in use on this mesh,
                // update it to use our new replacement versions.
                foreach (ModelMeshPart meshPart in mesh.MeshParts)
                {
                    meshPart.Effect = effectMapping[meshPart.Effect];
                }
            }
        }


        #endregion

        #region Update and Draw


        /// <summary>
        /// Allows the game to run logic.
        /// </summary>
        protected override void Update(GameTime gameTime)
        {
            HandleInput();

            // Update the sketch overlay texture jitter animation.
            if (Settings.SketchJitterSpeed > 0)
            {
                timeToNextJitter -= gameTime.ElapsedGameTime;

                if (timeToNextJitter <= TimeSpan.Zero)
                {
                    sketchJitter.X = (float)random.NextDouble();
                    sketchJitter.Y = (float)random.NextDouble();

                    timeToNextJitter += TimeSpan.FromSeconds(Settings.SketchJitterSpeed);
                }
            }

            base.Update(gameTime);
        }


        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice device = graphics.GraphicsDevice;

            // Calculate the camera matrices.
            float time = (float)gameTime.TotalGameTime.TotalSeconds;

            Matrix rotation = Matrix.CreateRotationY(time * 0.5f);

            Matrix view = Matrix.CreateLookAt(new Vector3(3000, 1500, 0),
                                              Vector3.Zero,
                                              Vector3.Up);

            Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4,
                                                                    device.Viewport.AspectRatio,
                                                                    1000, 10000);

            // If we are doing edge detection, first off we need to render the
            // normals and depth of our model into a special rendertarget.
            if (Settings.EnableEdgeDetect)
            {
                device.SetRenderTarget(normalDepthRenderTarget);
             
                device.Clear(Color.Black);

                DrawModel(rotation, view, projection, "NormalDepth");
            }

            // If we are doing edge detection and/or pencil sketch processing, we
            // need to draw the model into a special rendertarget which can then be
            // fed into the postprocessing shader. Otherwise can just draw it
            // directly onto the backbuffer.
            if (Settings.EnableEdgeDetect || Settings.EnableSketch)
                device.SetRenderTarget(sceneRenderTarget);
            else
                device.SetRenderTarget(null);

            device.Clear(Color.CornflowerBlue);

            // Draw the model, using either the cartoon or lambert shading technique.
            string effectTechniqueName;

            if (Settings.EnableToonShading)
                effectTechniqueName = "Toon";
            else
                effectTechniqueName = "Lambert";

            DrawModel(rotation, view, projection, effectTechniqueName);

            // Run the postprocessing filter over the scene that we just rendered.
            if (Settings.EnableEdgeDetect || Settings.EnableSketch)
            {
                device.SetRenderTarget(null);

                ApplyPostprocess();
            }

            // Display some text over the top. Note how we draw this after the
            // postprocessing, because we don't want the text to be affected by it.
            DrawOverlayText();

            base.Draw(gameTime);
        }


        /// <summary>
        /// Helper for drawing the spinning model using the specified effect technique.
        /// </summary>
        void DrawModel(Matrix world, Matrix view, Matrix projection,
                       string effectTechniqueName)
        {
            // Set suitable renderstates for drawing a 3D model.
            GraphicsDevice.BlendState = BlendState.Opaque;
            GraphicsDevice.DepthStencilState = DepthStencilState.Default;

            // Look up the bone transform matrices.
            Matrix[] transforms = new Matrix[model.Bones.Count];

            model.CopyAbsoluteBoneTransformsTo(transforms);

            // Draw the model.
            foreach (ModelMesh mesh in model.Meshes)
            {
                foreach (Effect effect in mesh.Effects)
                {
                    // Specify which effect technique to use.
                    effect.CurrentTechnique = effect.Techniques[effectTechniqueName];

                    Matrix localWorld = transforms[mesh.ParentBone.Index] * world;

                    effect.Parameters["World"].SetValue(localWorld);
                    effect.Parameters["View"].SetValue(view);
                    effect.Parameters["Projection"].SetValue(projection);
                }

                mesh.Draw();
            }
        }


        /// <summary>
        /// Helper applies the edge detection and pencil sketch postprocess effect.
        /// </summary>
        void ApplyPostprocess()
        {
            EffectParameterCollection parameters = postprocessEffect.Parameters;
            string effectTechniqueName;

            // Set effect parameters controlling the pencil sketch effect.
            if (Settings.EnableSketch)
            {
                parameters["SketchThreshold"].SetValue(Settings.SketchThreshold);
                parameters["SketchBrightness"].SetValue(Settings.SketchBrightness);
                parameters["SketchJitter"].SetValue(sketchJitter);
                parameters["SketchTexture"].SetValue(sketchTexture);
            }

            // Set effect parameters controlling the edge detection effect.
            if (Settings.EnableEdgeDetect)
            {
                Vector2 resolution = new Vector2(sceneRenderTarget.Width,
                                                 sceneRenderTarget.Height);

                Texture2D normalDepthTexture = normalDepthRenderTarget;

                parameters["EdgeWidth"].SetValue(Settings.EdgeWidth);
                parameters["EdgeIntensity"].SetValue(Settings.EdgeIntensity);
                parameters["ScreenResolution"].SetValue(resolution);
                parameters["NormalDepthTexture"].SetValue(normalDepthTexture);

                // Choose which effect technique to use.
                if (Settings.EnableSketch)
                {
                    if (Settings.SketchInColor)
                        effectTechniqueName = "EdgeDetectColorSketch";
                    else
                        effectTechniqueName = "EdgeDetectMonoSketch";
                }
                else
                    effectTechniqueName = "EdgeDetect";
            }
            else
            {
                // If edge detection is off, just pick one of the sketch techniques.
                if (Settings.SketchInColor)
                    effectTechniqueName = "ColorSketch";
                else
                    effectTechniqueName = "MonoSketch";
            }

            // Activate the appropriate effect technique.
            postprocessEffect.CurrentTechnique = postprocessEffect.Techniques[effectTechniqueName];

            // Draw a fullscreen sprite to apply the postprocessing effect.
            spriteBatch.Begin(0, BlendState.Opaque, null, null, null, postprocessEffect);
            spriteBatch.Draw(sceneRenderTarget, Vector2.Zero, Color.White);
            spriteBatch.End();
        }


        /// <summary>
        /// Displays an overlay showing what the controls are,
        /// and which settings are currently selected.
        /// </summary>
        void DrawOverlayText()
        {
            string text = "A = settings (" + Settings.Name + ")";

            spriteBatch.Begin();

            // Draw the string twice to create a drop shadow, first colored black
            // and offset one pixel to the bottom right, then again in white at the
            // intended position. This makes text easier to read over the background.
            spriteBatch.DrawString(spriteFont, text, new Vector2(65, 65), Color.Black);
            spriteBatch.DrawString(spriteFont, text, new Vector2(64, 64), Color.White);

            spriteBatch.End();
        }


        #endregion

        #region Handle Input


        /// <summary>
        /// Handles input for quitting or changing the display settings.
        /// </summary>
        void HandleInput()
        {
            lastKeyboardState = currentKeyboardState;
            lastGamePadState = currentGamePadState;

            currentKeyboardState = Keyboard.GetState();
            currentGamePadState = GamePad.GetState(PlayerIndex.One);

            // Check for exit.
            if (currentKeyboardState.IsKeyDown(Keys.Escape) ||
                currentGamePadState.Buttons.Back == ButtonState.Pressed)
            {
                Exit();
            }

            // Switch to the next settings preset?
            if ((currentGamePadState.Buttons.A == ButtonState.Pressed &&
                 lastGamePadState.Buttons.A != ButtonState.Pressed) ||
                (currentKeyboardState.IsKeyDown(Keys.A) &&
                 lastKeyboardState.IsKeyUp(Keys.A)))
            {
                settingsIndex = (settingsIndex + 1) %
                                NonPhotoRealisticSettings.PresetSettings.Length;
            }
        }


        #endregion
    }


    #region Entry Point

    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    static class Program
    {
        static void Main()
        {
            using (NonPhotoRealisticGame game = new NonPhotoRealisticGame())
            {
                game.Run();
            }
        }
    }

    #endregion
}