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

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

namespace GeneratedGeometry
{
    /// <summary>
    /// Sample showing how to use geometry that is programatically
    /// generated as part of the content pipeline build process.
    /// </summary>
    public class GeneratedGeometryGame : Microsoft.Xna.Framework.Game
    {
        #region Fields

        GraphicsDeviceManager graphics;

        Model terrain;
        Sky sky;

        #endregion

        #region Initialization


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

#if WINDOWS_PHONE
            // Frame rate is 30 fps by default for Windows Phone.
            TargetElapsedTime = TimeSpan.FromTicks(333333);

            graphics.IsFullScreen = true;
#endif
        }


        /// <summary>
        /// Load your graphics content.
        /// </summary>
        protected override void LoadContent()
        {
            terrain = Content.Load<Model>("terrain");
            sky = Content.Load<Sky>("sky");
        }


        #endregion

        #region Update and Draw


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


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

            device.Clear(Color.Black);

            // Calculate the projection matrix.
            Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4,
                                                                    device.Viewport.AspectRatio,
                                                                    1, 10000);

            // Calculate a view matrix, moving the camera around a circle.
            float time = (float)gameTime.TotalGameTime.TotalSeconds * 0.333f;

            float cameraX = (float)Math.Cos(time);
            float cameraY = (float)Math.Sin(time);

            Vector3 cameraPosition = new Vector3(cameraX, 0, cameraY) * 64;
            Vector3 cameraFront = new Vector3(-cameraY, 0, cameraX);

            Matrix view = Matrix.CreateLookAt(cameraPosition,
                                              cameraPosition + cameraFront,
                                              Vector3.Up);

            // Draw the terrain first, then the sky. This is faster than
            // drawing the sky first, because the depth buffer can skip
            // bothering to draw sky pixels that are covered up by the
            // terrain. This trick works because the code used to draw
            // the sky forces all the sky vertices to be as far away as
            // possible, and turns depth testing on but depth writes off.

            DrawTerrain(view, projection);

            sky.Draw(view, projection);

            // If there was any alpha blended translucent geometry in
            // the scene, that would be drawn here, after the sky.

            base.Draw(gameTime);
        }


        /// <summary>
        /// Helper for drawing the terrain model.
        /// </summary>
        void DrawTerrain(Matrix view, Matrix projection)
        {
            foreach (ModelMesh mesh in terrain.Meshes)
            {
                foreach (BasicEffect effect in mesh.Effects)
                {
                    effect.View = view;
                    effect.Projection = projection;

                    effect.EnableDefaultLighting();

                    // Set the specular lighting to match the sky color.
                    effect.SpecularColor = new Vector3(0.6f, 0.4f, 0.2f);
                    effect.SpecularPower = 8;

                    // Set the fog to match the distant mountains
                    // that are drawn into the sky texture.
                    effect.FogEnabled = true;
                    effect.FogColor = new Vector3(0.15f);
                    effect.FogStart = 100;
                    effect.FogEnd = 320;
                }

                mesh.Draw();
            }
        }


        #endregion

        #region Handle Input


        /// <summary>
        /// Handles input for quitting the game.
        /// </summary>
        private void HandleInput()
        {
            KeyboardState currentKeyboardState = Keyboard.GetState();
            GamePadState currentGamePadState = GamePad.GetState(PlayerIndex.One);

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


        #endregion
    }


    #region Entry Point

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

    #endregion
}