D:/guillaume/guillara/3D/DXGfx/DXCommon/wdxmutmisc.cs

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//--------------------------------------------------------------------------------------
// File: WDXMUTMisc.cs
//
// Shortcut and helper functions for using Managed DirectX for Whidbey Code
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//--------------------------------------------------------------------------------------
using System;
using System.IO;
using System.Collections;
using System.Runtime.InteropServices;
using Microsoft.DirectX;
using Microsoft.DirectX.Direct3D;

namespace Microsoft.Samples.DirectX.UtilityToolkit
{
    #region RefWarningDialog Form
    internal class SwitchRefDialog : System.Windows.Forms.Form
    {
        internal const string KeyLocation = @"Software\Microsoft\DirectX 9.0 SDK\ManagedSamples";
        internal const string KeyValueName = "SkipWarning";

        public SwitchRefDialog(string title)
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();

            // Use the 'question' icon
            this.pictureBox1.Image = System.Drawing.SystemIcons.Question.ToBitmap();
            // Include text
            this.lblInfo.Text = "Switching to the Direct3D reference rasterizer, a software device that implements the entire Direct3D feature set, but runs very slowly.\r\nDo you wish to continue?";
            // UPdate title
            this.Text = title;
        }

        #region Windows Form Designer generated code
        private System.Windows.Forms.PictureBox pictureBox1;
        private System.Windows.Forms.Label lblInfo;
        private System.Windows.Forms.CheckBox chkShowAgain;
        private System.Windows.Forms.Button btnYes;
        private System.Windows.Forms.Button btnNo;
        private void InitializeComponent()
        {
            this.pictureBox1 = new System.Windows.Forms.PictureBox();
            this.lblInfo = new System.Windows.Forms.Label();
            this.chkShowAgain = new System.Windows.Forms.CheckBox();
            this.btnYes = new System.Windows.Forms.Button();
            this.btnNo = new System.Windows.Forms.Button();
            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
            this.SuspendLayout();
            // 
            // pictureBox1
            // 
            this.pictureBox1.Location = new System.Drawing.Point(16, 16);
            this.pictureBox1.Name = "pictureBox1";
            this.pictureBox1.Size = new System.Drawing.Size(32, 32);
            this.pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.AutoSize;
            this.pictureBox1.TabIndex = 0;
            this.pictureBox1.TabStop = false;
            // 
            // lblInfo
            // 
            this.lblInfo.FlatStyle = System.Windows.Forms.FlatStyle.System;
            this.lblInfo.Location = new System.Drawing.Point(64, 16);
            this.lblInfo.Name = "lblInfo";
            this.lblInfo.Size = new System.Drawing.Size(328, 48);
            this.lblInfo.TabIndex = 99;
            // 
            // chkShowAgain
            // 
            this.chkShowAgain.FlatStyle = System.Windows.Forms.FlatStyle.System;
            this.chkShowAgain.Location = new System.Drawing.Point(8, 104);
            this.chkShowAgain.Name = "chkShowAgain";
            this.chkShowAgain.Size = new System.Drawing.Size(224, 16);
            this.chkShowAgain.TabIndex = 2;
            this.chkShowAgain.Text = "&Don\'t show again";
            // 
            // btnYes
            // 
            this.btnYes.DialogResult = System.Windows.Forms.DialogResult.OK;
            this.btnYes.FlatStyle = System.Windows.Forms.FlatStyle.System;
            this.btnYes.Location = new System.Drawing.Point(117, 72);
            this.btnYes.Name = "btnYes";
            this.btnYes.Size = new System.Drawing.Size(80, 24);
            this.btnYes.TabIndex = 0;
            this.btnYes.Text = "&Yes";
            this.btnYes.Click += new EventHandler(OnYes);
            // 
            // btnNo
            // 
            this.btnNo.DialogResult = System.Windows.Forms.DialogResult.Cancel;
            this.btnNo.FlatStyle = System.Windows.Forms.FlatStyle.System;
            this.btnNo.Location = new System.Drawing.Point(205, 72);
            this.btnNo.Name = "btnNo";
            this.btnNo.Size = new System.Drawing.Size(80, 24);
            this.btnNo.TabIndex = 1;
            this.btnNo.Text = "&No";
            this.btnNo.Click += new EventHandler(OnNo);
            // 
            // SwitchRefDialog
            // 
            this.AcceptButton = this.btnYes;
            this.CancelButton = this.btnNo;
            this.ClientSize = new System.Drawing.Size(402, 134);
            this.Controls.Add(this.btnNo);
            this.Controls.Add(this.btnYes);
            this.Controls.Add(this.chkShowAgain);
            this.Controls.Add(this.lblInfo);
            this.Controls.Add(this.pictureBox1);
            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
            this.Name = "SwitchRefDialog";
            this.Text = "SampleName";
            this.ResumeLayout(false);

        }
        private void OnYes(object sender, EventArgs e)
        {
            this.DialogResult = System.Windows.Forms.DialogResult.OK;
            this.Close();
        }
        private void OnNo(object sender, EventArgs e)
        {
            this.DialogResult = System.Windows.Forms.DialogResult.Cancel;
            this.Close();
        }
        #endregion

        protected override void OnClosed(EventArgs e)
        {
            // Is the box checked?
            if (chkShowAgain.Checked)
            {
                using (Microsoft.Win32.RegistryKey key = Microsoft.Win32.Registry.CurrentUser.CreateSubKey(KeyLocation))
                {
                    key.SetValue(KeyValueName, (int)1);
                }
            }
        }
    }
    #endregion

    #region Native Methods
    public class NativeMethods
    {
        #region Win32 User Messages / Structures

        public enum WindowMessage : uint
        {
            // Misc messages
            Destroy = 0x0002,
            Close = 0x0010,
            Quit = 0x0012,
            Paint = 0x000F,
            SetCursor = 0x0020,
            ActivateApplication = 0x001C,
            EnterMenuLoop = 0x0211,
            ExitMenuLoop = 0x0212,
            NonClientHitTest = 0x0084,
            PowerBroadcast = 0x0218,
            SystemCommand = 0x0112,
            GetMinMax = 0x0024,

            // Keyboard messages
            KeyDown = 0x0100,
            KeyUp = 0x0101,
            Character = 0x0102,
            SystemKeyDown = 0x0104,
            SystemKeyUp = 0x0105,
            SystemCharacter = 0x0106,

            // Mouse messages
            MouseMove = 0x0200,
            LeftButtonDown = 0x0201,
            LeftButtonUp = 0x0202,
            LeftButtonDoubleClick = 0x0203,
            RightButtonDown = 0x0204,
            RightButtonUp = 0x0205,
            RightButtonDoubleClick = 0x0206,
            MiddleButtonDown = 0x0207,
            MiddleButtonUp = 0x0208,
            MiddleButtonDoubleClick = 0x0209,
            MouseWheel = 0x020a,
            XButtonDown = 0x020B,
            XButtonUp = 0x020c,
            XButtonDoubleClick = 0x020d,
            MouseFirst = LeftButtonDown, // Skip mouse move, it happens a lot and there is another message for that
            MouseLast = XButtonDoubleClick,

            // Sizing
            EnterSizeMove = 0x0231,
            ExitSizeMove = 0x0232,
            Size = 0x0005,

        }

        public enum MouseButtons
        {
            Left = 0x0001,
            Right = 0x0002,
            Middle = 0x0010,
            Side1 = 0x0020,
            Side2 = 0x0040,
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct Message
        {
            public IntPtr hWnd;
            public WindowMessage msg;
            public IntPtr wParam;
            public IntPtr lParam;
            public uint time;
            public System.Drawing.Point p;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct MinMaxInformation
        {
            public System.Drawing.Point reserved;
            public System.Drawing.Point MaxSize;
            public System.Drawing.Point MaxPosition;
            public System.Drawing.Point MinTrackSize;
            public System.Drawing.Point MaxTrackSize;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct MonitorInformation
        {
            public uint Size; // Size of this structure
            public System.Drawing.Rectangle MonitorRectangle;
            public System.Drawing.Rectangle WorkRectangle;
            public uint Flags; // Possible flags
        }
        #endregion

        #region Windows API calls
        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [System.Runtime.InteropServices.DllImport("winmm.dll")]
        public static extern IntPtr timeBeginPeriod(uint period);

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("kernel32")]
        public static extern bool QueryPerformanceFrequency(ref long PerformanceFrequency);

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("kernel32")]
        public static extern bool QueryPerformanceCounter(ref long PerformanceCount);

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern bool GetMonitorInfo(IntPtr hWnd, ref MonitorInformation info);

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern IntPtr MonitorFromWindow(IntPtr hWnd, uint flags);

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern short GetAsyncKeyState(uint key);

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern IntPtr SetCapture(IntPtr handle);

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern bool ReleaseCapture();

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern int GetCaretBlinkTime();

        [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern bool PeekMessage(out Message msg, IntPtr hWnd, uint messageFilterMin, uint messageFilterMax, uint flags);
        #endregion

        #region Class Methods
        private NativeMethods() { } // No creation
        public static short LoWord(uint l)
        {
            return (short)(l & 0xffff);
        }
        public static short HiWord(uint l)
        {
            return (short)(l >> 16);
        }

        public static uint MakeUInt32(short l, short r)
        {
            return (uint)((l & 0xffff) | ((r & 0xffff) << 16));
        }

        public static bool IsKeyDown(System.Windows.Forms.Keys key)
        {
            return (GetAsyncKeyState((int)System.Windows.Forms.Keys.ShiftKey) & 0x8000) != 0;
        }
        #endregion
    }

    #endregion

    #region Timer
    public class FrameworkTimer
    {
        #region Instance Data
        private static bool isUsingQPF;
        private static bool isTimerStopped;
        private static long ticksPerSecond;
        private static long stopTime;
        private static long lastElapsedTime;
        private static long baseTime;
        #endregion

        #region Creation
        private FrameworkTimer() { } // No creation
        static FrameworkTimer()
        {
            isTimerStopped = true;
            ticksPerSecond = 0;
            stopTime = 0;
            lastElapsedTime = 0;
            baseTime = 0;
            // Use QueryPerformanceFrequency to get frequency of the timer
            isUsingQPF = NativeMethods.QueryPerformanceFrequency(ref ticksPerSecond);
        }
        #endregion

        public static void Reset()
        {
            if (!isUsingQPF)
                return; // Nothing to do

            // Get either the current time or the stop time
            long time = 0;
            if (stopTime != 0)
                time = stopTime;
            else
                NativeMethods.QueryPerformanceCounter(ref time);

            baseTime = time;
            lastElapsedTime = time;
            stopTime = 0;
            isTimerStopped = false;
        }

        public static void Start()
        {
            if (!isUsingQPF)
                return; // Nothing to do

            // Get either the current time or the stop time
            long time = 0;
            if (stopTime != 0)
                time = stopTime;
            else
                NativeMethods.QueryPerformanceCounter(ref time);

            if (isTimerStopped)
                baseTime += (time - stopTime);
            stopTime = 0;
            lastElapsedTime = time;
            isTimerStopped = false;
        }

        public static void Stop()
        {
            if (!isUsingQPF)
                return; // Nothing to do

            if (!isTimerStopped)
            {
                // Get either the current time or the stop time
                long time = 0;
                if (stopTime != 0)
                    time = stopTime;
                else
                    NativeMethods.QueryPerformanceCounter(ref time);

                stopTime = time;
                lastElapsedTime = time;
                isTimerStopped = true;
            }
        }

        public static void Advance()
        {
            if (!isUsingQPF)
                return; // Nothing to do

            stopTime += ticksPerSecond / 10;
        }

        public static double GetAbsoluteTime()
        {
            if (!isUsingQPF)
                return -1.0; // Nothing to do

            // Get either the current time or the stop time
            long time = 0;
            if (stopTime != 0)
                time = stopTime;
            else
                NativeMethods.QueryPerformanceCounter(ref time);

            double absolueTime = time / (double)ticksPerSecond;
            return absolueTime;
        }

        public static double GetTime()
        {
            if (!isUsingQPF)
                return -1.0; // Nothing to do

            // Get either the current time or the stop time
            long time = 0;
            if (stopTime != 0)
                time = stopTime;
            else
                NativeMethods.QueryPerformanceCounter(ref time);

            double appTime = (double)(time - baseTime) / (double)ticksPerSecond;
            return appTime;
        }

        public static double GetElapsedTime()
        {
            if (!isUsingQPF)
                return -1.0; // Nothing to do

            // Get either the current time or the stop time
            long time = 0;
            if (stopTime != 0)
                time = stopTime;
            else
                NativeMethods.QueryPerformanceCounter(ref time);

            double elapsedTime = (double)(time - lastElapsedTime) / (double)ticksPerSecond;
            lastElapsedTime = time;
            return elapsedTime;
        }

        public static bool IsStopped
        {
            get { return isTimerStopped; }
        }
    }
    #endregion

    #region Resource Cache
    struct CachedTexture
    {
        public string Source; // Data source
        public int Width;
        public int Height;
        public int Depth;
        public int MipLevels;
        public Usage Usage;
        public Format Format;
        public Pool Pool;
        public ResourceType Type;
    }

    struct CachedEffect
    {
        public string Source; // Data source
        public ShaderFlags Flags;
    }

    public class ResourceCache
    {
        #region Creation
        private ResourceCache() { } // Don't allow creation
        private static ResourceCache localObject = null;
        public static ResourceCache GetGlobalInstance()
        {
            if (localObject == null)
                localObject = new ResourceCache();

            return localObject;
        }
        #endregion

        protected Hashtable textureCache = new Hashtable(); // Cache of textures
        protected Hashtable effectCache = new Hashtable(); // Cache of effects
        protected Hashtable fontCache = new Hashtable(); // Cache of fonts

        #region Cache Creation Methods

        public Texture CreateTextureFromFile(Device device, string filename)
        {
            return CreateTextureFromFileEx(device, filename, Constants.Default, Constants.Default, Constants.Default, Usage.None,
                Format.Unknown, Pool.Managed, (Filter)Constants.Default, (Filter)Constants.Default, 0);
        }
        public Texture CreateTextureFromFileEx(Device device, string filename, int w, int h, int mip, Usage usage, Format fmt, Pool pool, Filter filter, Filter mipfilter, int colorkey)
        {
            // Search the cache first
            foreach (CachedTexture ct in textureCache.Keys)
            {
                if ((string.Compare(ct.Source, filename, true) == 0) &&
                    ct.Width == w &&
                    ct.Height == h &&
                    ct.MipLevels == mip &&
                    ct.Usage == usage &&
                    ct.Format == fmt &&
                    ct.Pool == pool &&
                    ct.Type == ResourceType.Texture)
                {
                    // A match was found, return that
                    return textureCache[ct] as Texture;
                }
            }

            // No matching entry, load the resource and add it to the cache
            Texture t = new Texture(device, filename, w, h, mip, usage, fmt, pool, filter, mipfilter, colorkey, false, null);
            CachedTexture entry = new CachedTexture();
            entry.Source = filename;
            entry.Width = w;
            entry.Height = h;
            entry.MipLevels = mip;
            entry.Usage = usage;
            entry.Format = fmt;
            entry.Pool = pool;
            entry.Type = ResourceType.Texture;

            textureCache.Add(entry, t);

            return t;
        }
        public CubeTexture CreateCubeTextureFromFile(Device device, string filename)
        {
            return CreateCubeTextureFromFileEx(device, filename, Constants.Default, Constants.Default, Usage.None,
                Format.Unknown, Pool.Managed, (Filter)Constants.Default, (Filter)Constants.Default, 0);
        }
        public CubeTexture CreateCubeTextureFromFileEx(Device device, string filename, int size, int mip, Usage usage, Format fmt, Pool pool, Filter filter, Filter mipfilter, int colorkey)
        {
            // Search the cache first
            foreach (CachedTexture ct in textureCache.Keys)
            {
                if ((string.Compare(ct.Source, filename, true) == 0) &&
                    ct.Width == size &&
                    ct.MipLevels == mip &&
                    ct.Usage == usage &&
                    ct.Format == fmt &&
                    ct.Pool == pool &&
                    ct.Type == ResourceType.CubeTexture)
                {
                    // A match was found, return that
                    return textureCache[ct] as CubeTexture;
                }
            }

            // No matching entry, load the resource and add it to the cache
            CubeTexture t = new CubeTexture(device, filename, size, mip, usage, fmt, pool, filter, mipfilter, colorkey, false, null);
            CachedTexture entry = new CachedTexture();
            entry.Source = filename;
            entry.Width = size;
            entry.MipLevels = mip;
            entry.Usage = usage;
            entry.Format = fmt;
            entry.Pool = pool;
            entry.Type = ResourceType.CubeTexture;

            textureCache.Add(entry, t);

            return t;
        }
        public VolumeTexture CreateVolumeTextureFromFile(Device device, string filename)
        {
            return CreateVolumeTextureFromFileEx(device, filename, Constants.Default, Constants.Default, Constants.Default, Constants.Default, Usage.None,
                Format.Unknown, Pool.Managed, (Filter)Constants.Default, (Filter)Constants.Default, 0);
        }
        public VolumeTexture CreateVolumeTextureFromFileEx(Device device, string filename, int w, int h, int d, int mip, Usage usage, Format fmt, Pool pool, Filter filter, Filter mipfilter, int colorkey)
        {
            // Search the cache first
            foreach (CachedTexture ct in textureCache.Keys)
            {
                if ((string.Compare(ct.Source, filename, true) == 0) &&
                    ct.Width == w &&
                    ct.Height == h &&
                    ct.Depth == d &&
                    ct.MipLevels == mip &&
                    ct.Usage == usage &&
                    ct.Format == fmt &&
                    ct.Pool == pool &&
                    ct.Type == ResourceType.VolumeTexture)
                {
                    // A match was found, return that
                    return textureCache[ct] as VolumeTexture;
                }
            }

            // No matching entry, load the resource and add it to the cache
            VolumeTexture t = new VolumeTexture(device, filename, w, h, d, mip, usage, fmt, pool, filter, mipfilter, colorkey, false, null);
            CachedTexture entry = new CachedTexture();
            entry.Source = filename;
            entry.Width = w;
            entry.Height = h;
            entry.Depth = d;
            entry.MipLevels = mip;
            entry.Usage = usage;
            entry.Format = fmt;
            entry.Pool = pool;
            entry.Type = ResourceType.VolumeTexture;

            textureCache.Add(entry, t);

            return t;
        }

        public Effect CreateEffectFromFile(Device device, string filename, Macro[] defines, Include includeFile, ShaderFlags flags, EffectPool effectPool)
        {
            // Search the cache first
            foreach (CachedEffect ce in effectCache.Keys)
            {
                if ((string.Compare(ce.Source, filename, true) == 0) &&
                    ce.Flags == flags)
                {
                    // A match was found, return that
                    return effectCache[ce] as Effect;
                }
            }

            // Nothing found in the cache
            Effect e = Effect.FromFile(device, filename, defines, includeFile, null, flags, effectPool);
            // Add this to the cache
            CachedEffect entry = new CachedEffect();
            entry.Flags = flags;
            entry.Source = filename;
            effectCache.Add(entry, e);

            // Return the new effect
            return e;
        }

        public Font CreateFont(Device device, int height, int width, FontWeight weight, int mip, bool italic,
            CharacterSet charSet, Precision outputPrecision, FontQuality quality, PitchAndFamily pandf, string fontName)
        {
            // Create the font description
            FontDescription desc = new FontDescription();
            desc.Height = height;
            desc.Width = width;
            desc.Weight = weight;
            desc.MipLevels = mip;
            desc.IsItalic = italic;
            desc.CharacterSet = charSet;
            desc.OutputPrecision = outputPrecision;
            desc.Quality = quality;
            desc.PitchAndFamily = pandf;
            desc.FaceName = fontName;

            // return the font
            return CreateFont(device, desc);
        }
        public Font CreateFont(Device device, FontDescription desc)
        {
            // Search the cache first
            foreach (FontDescription fd in fontCache.Keys)
            {
                if ((string.Compare(fd.FaceName, desc.FaceName, true) == 0) &&
                    fd.CharacterSet == desc.CharacterSet &&
                    fd.Height == desc.Height &&
                    fd.IsItalic == desc.IsItalic &&
                    fd.MipLevels == desc.MipLevels &&
                    fd.OutputPrecision == desc.OutputPrecision &&
                    fd.PitchAndFamily == desc.PitchAndFamily &&
                    fd.Quality == desc.Quality &&
                    fd.Weight == desc.Weight &&
                    fd.Width == desc.Width)
                {
                    // A match was found, return that
                    return fontCache[fd] as Font;
                }
            }

            // Couldn't find anything in the cache, create one
            Font f = new Font(device, desc);
            // Create a new entry
            fontCache.Add(desc, f);

            // return the new font
            return f;
        }

        #endregion

        #region Device event callbacks
        public void OnCreateDevice(Device device) { } // Nothing to do on device create
        public void OnResetDevice(Device device)
        {
            // Call OnResetDevice on all effect and font objects
            foreach (Font f in fontCache.Values)
                f.OnResetDevice();
            foreach (Effect e in effectCache.Values)
                e.OnResetDevice();
        }
        public void OnLostDevice()
        {
            foreach (Font f in fontCache.Values)
                f.OnLostDevice();
            foreach (Effect e in effectCache.Values)
                e.OnLostDevice();

            // Search the texture cache 
            foreach (CachedTexture ct in textureCache.Keys)
            {
                if (ct.Pool == Pool.Default)
                {
                    // A match was found, get rid of it
                    switch (ct.Type)
                    {
                        case ResourceType.Texture:
                            (textureCache[ct] as Texture).Dispose(); break;
                        case ResourceType.CubeTexture:
                            (textureCache[ct] as CubeTexture).Dispose(); break;
                        case ResourceType.VolumeTexture:
                            (textureCache[ct] as VolumeTexture).Dispose(); break;
                    }
                }
            }
        }
        public void OnDestroyDevice()
        {
            // Cleanup the fonts
            foreach (Font f in fontCache.Values)
                f.Dispose();

            // Cleanup the effects
            foreach (Effect e in effectCache.Values)
                e.Dispose();

            // Dispose of any items in the caches
            foreach (BaseTexture texture in textureCache.Values)
            {
                if (texture != null)
                    texture.Dispose();
            }

            // Clear all of the caches
            textureCache.Clear();
            fontCache.Clear();
            effectCache.Clear();
        }

        #endregion
    }
    #endregion

    #region Arcball
    public class ArcBall
    {
        #region Instance Data
        protected Matrix rotation; // Matrix for arc ball's orientation
        protected Matrix translation; // Matrix for arc ball's position
        protected Matrix translationDelta; // Matrix for arc ball's position

        protected int width; // arc ball's window width
        protected int height; // arc ball's window height
        protected Vector2 center;  // center of arc ball 
        protected float radius; // arc ball's radius in screen coords
        protected float radiusTranslation; // arc ball's radius for translating the target

        protected Quaternion downQuat; // Quaternion before button down
        protected Quaternion nowQuat; // Composite quaternion for current drag
        protected bool isDragging; // Whether user is dragging arc ball

        protected System.Drawing.Point lastMousePosition; // position of last mouse point
        protected Vector3 downPt; // starting point of rotation arc
        protected Vector3 currentPt; // current point of rotation arc
        #endregion

        #region Simple Properties
        public Matrix RotationMatrix { get { return rotation = Matrix.RotationQuaternion(nowQuat); } }
        public Matrix TranslationMatrix { get { return translation; } }
        public Matrix TranslationDeltaMatrix { get { return translationDelta; } }
        public bool IsBeingDragged { get { return isDragging; } }
        public Quaternion CurrentQuaternion { get { return nowQuat; } set { nowQuat = value; } }
        #endregion

        // Class methods

        public ArcBall()
        {
            Reset();
            downPt = Vector3.Empty;
            currentPt = Vector3.Empty;

            System.Windows.Forms.Form active = System.Windows.Forms.Form.ActiveForm;
            if (active != null)
            {
                System.Drawing.Rectangle rect = active.ClientRectangle;
                SetWindow(rect.Width, rect.Height);
            }
        }

        public void Reset()
        {
            downQuat = Quaternion.Identity;
            nowQuat = Quaternion.Identity;
            rotation = Matrix.Identity;
            translation = Matrix.Identity;
            translationDelta = Matrix.Identity;
            isDragging = false;
            radius = 1.0f;
            radiusTranslation = 1.0f;
        }

        public Vector3 ScreenToVector(float screenPointX, float screenPointY)
        {
            float x = -(screenPointX - width / 2.0f) / (radius * width / 2.0f);
            float y = (screenPointY - height / 2.0f) / (radius * height / 2.0f);
            float z = 0.0f;
            float mag = (x * x) + (y * y);

            if (mag > 1.0f)
            {
                float scale = 1.0f / (float)Math.Sqrt(mag);
                x *= scale;
                y *= scale;
            }
            else
                z = (float)Math.Sqrt(1.0f - mag);

            return new Vector3(x, y, z);
        }

        public void SetWindow(int w, int h, float r)
        {
            width = w; height = h; radius = r;
            center = new Vector2(w / 2.0f, h / 2.0f);
        }
        public void SetWindow(int w, int h)
        {
            SetWindow(w, h, 0.9f); // default radius
        }

        public static Quaternion QuaternionFromBallPoints(Vector3 from, Vector3 to)
        {
            float dot = Vector3.DotProduct(from, to);
            Vector3 part = Vector3.CrossProduct(from, to);
            return new Quaternion(part.X, part.Y, part.Z, dot);
        }

        public void OnBegin(int x, int y)
        {
            isDragging = true;
            downQuat = nowQuat;
            downPt = ScreenToVector((float)x, (float)y);
        }
        public void OnMove(int x, int y)
        {
            if (isDragging)
            {
                currentPt = ScreenToVector((float)x, (float)y);
                nowQuat = downQuat * QuaternionFromBallPoints(downPt, currentPt);
            }
        }
        public void OnEnd()
        {
            isDragging = false;
        }

        public bool HandleMessages(IntPtr hWnd, NativeMethods.WindowMessage msg, IntPtr wParam, IntPtr lParam)
        {
            // Current mouse position
            short mouseX = NativeMethods.LoWord((uint)lParam.ToInt32());
            short mouseY = NativeMethods.HiWord((uint)lParam.ToInt32());

            switch (msg)
            {
                case NativeMethods.WindowMessage.LeftButtonDown:
                case NativeMethods.WindowMessage.LeftButtonDoubleClick:
                    // Set capture
                    NativeMethods.SetCapture(hWnd);
                    OnBegin(mouseX, mouseY);
                    return true;
                case NativeMethods.WindowMessage.LeftButtonUp:
                    // Release capture
                    NativeMethods.ReleaseCapture();
                    OnEnd();
                    return true;

                case NativeMethods.WindowMessage.RightButtonDown:
                case NativeMethods.WindowMessage.RightButtonDoubleClick:
                case NativeMethods.WindowMessage.MiddleButtonDown:
                case NativeMethods.WindowMessage.MiddleButtonDoubleClick:
                    // Set capture
                    NativeMethods.SetCapture(hWnd);
                    // Store off the position of the cursor
                    lastMousePosition = new System.Drawing.Point(mouseX, mouseY);
                    return true;

                case NativeMethods.WindowMessage.RightButtonUp:
                case NativeMethods.WindowMessage.MiddleButtonUp:
                    // Release capture
                    NativeMethods.ReleaseCapture();
                    return true;

                case NativeMethods.WindowMessage.MouseMove:
                    short buttonState = NativeMethods.LoWord((uint)wParam.ToInt32());
                    bool leftButton = ((buttonState & (short)NativeMethods.MouseButtons.Left) != 0);
                    bool rightButton = ((buttonState & (short)NativeMethods.MouseButtons.Right) != 0);
                    bool middleButton = ((buttonState & (short)NativeMethods.MouseButtons.Middle) != 0);

                    if (leftButton)
                    {
                        OnMove(mouseX, mouseY);
                    }
                    else if (rightButton || middleButton)
                    {
                        // Normalize based on size of window and bounding sphere radius
                        float deltaX = (lastMousePosition.X - mouseX) * radiusTranslation / width;
                        float deltaY = (lastMousePosition.Y - mouseY) * radiusTranslation / height;

                        if (rightButton)
                        {
                            translationDelta = Matrix.Translation(-2 * deltaX, 2 * deltaY, 0.0f);
                            translation *= translationDelta;
                        }
                        else // Middle button
                        {
                            translationDelta = Matrix.Translation(0.0f, 0.0f, 5 * deltaY);
                            translation *= translationDelta;
                        }
                        // Store off the position of the cursor
                        lastMousePosition = new System.Drawing.Point(mouseX, mouseY);
                    }
                    return true;
            }

            return false;
        }
    }
    #endregion

    #region Cameras
    public enum CameraKeys : byte
    {
        StrafeLeft,
        StrafeRight,
        MoveForward,
        MoveBackward,
        MoveUp,
        MoveDown,
        Reset,
        ControlDown,
        MaxKeys,
        Unknown = 0xff
    }

    [Flags]
    public enum MouseButtonMask : byte
    {
        None = 0,
        Left = 0x01,
        Middle = 0x02,
        Right = 0x04,
        Wheel = 0x08,
    }

    public abstract class Camera
    {
        protected static CameraKeys MapKey(IntPtr param)
        {
            System.Windows.Forms.Keys key = (System.Windows.Forms.Keys)param.ToInt32();
            switch (key)
            {
                case System.Windows.Forms.Keys.ControlKey: return CameraKeys.ControlDown;
                case System.Windows.Forms.Keys.Left: return CameraKeys.StrafeLeft;
                case System.Windows.Forms.Keys.Right: return CameraKeys.StrafeRight;
                case System.Windows.Forms.Keys.Up: return CameraKeys.MoveForward;
                case System.Windows.Forms.Keys.Down: return CameraKeys.MoveBackward;
                case System.Windows.Forms.Keys.Prior: return CameraKeys.MoveUp; // pgup
                case System.Windows.Forms.Keys.Next: return CameraKeys.MoveDown; // pgdn

                case System.Windows.Forms.Keys.A: return CameraKeys.StrafeLeft;
                case System.Windows.Forms.Keys.D: return CameraKeys.StrafeRight;
                case System.Windows.Forms.Keys.W: return CameraKeys.MoveForward;
                case System.Windows.Forms.Keys.S: return CameraKeys.MoveBackward;
                case System.Windows.Forms.Keys.Q: return CameraKeys.MoveUp;
                case System.Windows.Forms.Keys.E: return CameraKeys.MoveDown;

                case System.Windows.Forms.Keys.NumPad4: return CameraKeys.StrafeLeft;
                case System.Windows.Forms.Keys.NumPad6: return CameraKeys.StrafeRight;
                case System.Windows.Forms.Keys.NumPad8: return CameraKeys.MoveForward;
                case System.Windows.Forms.Keys.NumPad2: return CameraKeys.MoveBackward;
                case System.Windows.Forms.Keys.NumPad9: return CameraKeys.MoveUp;
                case System.Windows.Forms.Keys.NumPad3: return CameraKeys.MoveDown;

                case System.Windows.Forms.Keys.Home: return CameraKeys.Reset;
            }
            // No idea
            return (CameraKeys)byte.MaxValue;
        }


        #region Instance Data
        protected Matrix viewMatrix; // View Matrix
        protected Matrix projMatrix; // Projection matrix

        protected System.Drawing.Point lastMousePosition;  // Last absolute position of mouse cursor
        protected bool isMouseLButtonDown;    // True if left button is down 
        protected bool isMouseMButtonDown;    // True if middle button is down 
        protected bool isMouseRButtonDown;    // True if right button is down 
        protected int currentButtonMask;   // mask of which buttons are down
        protected int mouseWheelDelta;     // Amount of middle wheel scroll (+/-) 
        protected Vector2 mouseDelta;          // Mouse relative delta smoothed over a few frames
        protected float framesToSmoothMouseData; // Number of frames to smooth mouse data over

        protected Vector3 defaultEye;          // Default camera eye position
        protected Vector3 defaultLookAt;       // Default LookAt position
        protected Vector3 eye;                 // Camera eye position
        protected Vector3 lookAt;              // LookAt position
        protected float cameraYawAngle;      // Yaw angle of camera
        protected float cameraPitchAngle;    // Pitch angle of camera

        protected System.Drawing.Rectangle dragRectangle; // Rectangle within which a drag can be initiated.
        protected Vector3 velocity;            // Velocity of camera
        protected bool isMovementDrag;        // If true, then camera movement will slow to a stop otherwise movement is instant
        protected Vector3 velocityDrag;        // Velocity drag force
        protected float dragTimer;           // Countdown timer to apply drag
        protected float totalDragTimeToZero; // Time it takes for velocity to go from full to 0
        protected Vector2 rotationVelocity;         // Velocity of camera

        protected float fieldOfView;                 // Field of view
        protected float aspectRatio;              // Aspect ratio
        protected float nearPlane;           // Near plane
        protected float farPlane;            // Far plane

        protected float rotationScaler;      // Scaler for rotation
        protected float moveScaler;          // Scaler for movement

        protected bool isInvertPitch;         // Invert the pitch axis
        protected bool isEnablePositionMovement; // If true, then the user can translate the camera/model 
        protected bool isEnableYAxisMovement; // If true, then camera can move in the y-axis

        protected bool isClipToBoundary;      // If true, then the camera will be clipped to the boundary
        protected Vector3 minBoundary;         // Min point in clip boundary
        protected Vector3 maxBoundary;         // Max point in clip boundary

        protected bool isResetCursorAfterMove;// If true, the class will reset the cursor position so that the cursor always has space to move 

        // State of the input
        protected bool[] keys;
        public static readonly Vector3 UpDirection = new Vector3(0, 1, 0);
        #endregion

        #region Simple Properties
        public bool IsBeingDragged { get { return (isMouseLButtonDown || isMouseMButtonDown || isMouseRButtonDown); } }
        public bool IsMouseLeftButtonDown { get { return isMouseLButtonDown; } }
        public bool IsMouseRightButtonDown { get { return isMouseRButtonDown; } }
        public bool IsMouseMiddleButtonDown { get { return isMouseMButtonDown; } }
        public Matrix ViewMatrix { get { return viewMatrix; } }
        public Matrix ProjectionMatrix { get { return projMatrix; } }
        public Vector3 EyeLocation { get { return eye; } }
        public Vector3 LookAtPoint { get { return lookAt; } }
        public bool IsPositionMovementEnabled { get { return isEnablePositionMovement; } set { isEnablePositionMovement = value; } }
        #endregion

        public abstract void FrameMove(float elapsedTime);

        protected Camera()
        {
            // Create the keys
            keys = new bool[(int)CameraKeys.MaxKeys];

            // Set attributes for the view matrix
            eye = Vector3.Empty;
            lookAt = new Vector3(0.0f, 0.0f, 1.0f);

            // Setup the view matrix
            SetViewParameters(eye, lookAt);

            // Setup the projection matrix
            SetProjectionParameters((float)Math.PI / 4, 1.0f, 1.0f, 1000.0f);

            // Store mouse information
            lastMousePosition = System.Windows.Forms.Cursor.Position;
            isMouseLButtonDown = false;
            isMouseRButtonDown = false;
            isMouseMButtonDown = false;
            mouseWheelDelta = 0;
            currentButtonMask = 0;

            // Setup camera rotations
            cameraYawAngle = 0.0f;
            cameraPitchAngle = 0.0f;

            dragRectangle = new System.Drawing.Rectangle(0, 0, int.MaxValue, int.MaxValue);
            velocity = Vector3.Empty;
            isMovementDrag = false;
            velocityDrag = Vector3.Empty;
            dragTimer = 0.0f;
            totalDragTimeToZero = 0.25f;
            rotationVelocity = Vector2.Empty;
            rotationScaler = 0.1f;
            moveScaler = 5.0f;
            isInvertPitch = false;
            isEnableYAxisMovement = true;
            isEnablePositionMovement = true;
            mouseDelta = Vector2.Empty;
            framesToSmoothMouseData = 2.0f;
            isClipToBoundary = false;
            minBoundary = new Vector3(-1.0f, -1.0f, -1.0f);
            maxBoundary = new Vector3(1, 1, 1);
            isResetCursorAfterMove = false;
        }

        public virtual bool HandleMessages(IntPtr hWnd, NativeMethods.WindowMessage msg, IntPtr wParam, IntPtr lParam)
        {
            switch (msg)
            {
                // Handle the keyboard
                case NativeMethods.WindowMessage.KeyDown:
                    CameraKeys mappedKeyDown = MapKey(wParam);
                    if (mappedKeyDown != (CameraKeys)byte.MaxValue)
                    {
                        // Valid key was pressed, mark it as 'down'
                        keys[(int)mappedKeyDown] = true;
                    }
                    break;
                case NativeMethods.WindowMessage.KeyUp:
                    CameraKeys mappedKeyUp = MapKey(wParam);
                    if (mappedKeyUp != (CameraKeys)byte.MaxValue)
                    {
                        // Valid key was let go, mark it as 'up'
                        keys[(int)mappedKeyUp] = false;
                    }
                    break;

                // Handle the mouse
                case NativeMethods.WindowMessage.LeftButtonDoubleClick:
                case NativeMethods.WindowMessage.LeftButtonDown:
                case NativeMethods.WindowMessage.RightButtonDoubleClick:
                case NativeMethods.WindowMessage.RightButtonDown:
                case NativeMethods.WindowMessage.MiddleButtonDoubleClick:
                case NativeMethods.WindowMessage.MiddleButtonDown:
                    {
                        // Compute the drag rectangle in screen coord.
                        System.Drawing.Point cursor = new System.Drawing.Point(
                            NativeMethods.LoWord((uint)lParam.ToInt32()),
                            NativeMethods.HiWord((uint)lParam.ToInt32()));

                        // Update the variable state
                        if (((msg == NativeMethods.WindowMessage.LeftButtonDown) ||
                            (msg == NativeMethods.WindowMessage.LeftButtonDoubleClick))
                            && dragRectangle.Contains(cursor))
                        {
                            isMouseLButtonDown = true; currentButtonMask |= (int)MouseButtonMask.Left;
                        }
                        if (((msg == NativeMethods.WindowMessage.MiddleButtonDown) ||
                            (msg == NativeMethods.WindowMessage.MiddleButtonDoubleClick))
                            && dragRectangle.Contains(cursor))
                        {
                            isMouseMButtonDown = true; currentButtonMask |= (int)MouseButtonMask.Middle;
                        }
                        if (((msg == NativeMethods.WindowMessage.RightButtonDown) ||
                            (msg == NativeMethods.WindowMessage.RightButtonDoubleClick))
                            && dragRectangle.Contains(cursor))
                        {
                            isMouseRButtonDown = true; currentButtonMask |= (int)MouseButtonMask.Right;
                        }

                        // Capture the mouse, so if the mouse button is 
                        // released outside the window, we'll get the button up messages
                        NativeMethods.SetCapture(hWnd);

                        lastMousePosition = System.Windows.Forms.Cursor.Position;
                        return true;
                    }
                case NativeMethods.WindowMessage.LeftButtonUp:
                case NativeMethods.WindowMessage.RightButtonUp:
                case NativeMethods.WindowMessage.MiddleButtonUp:
                    {
                        // Update member var state
                        if (msg == NativeMethods.WindowMessage.LeftButtonUp) { isMouseLButtonDown = false; currentButtonMask &= ~(int)MouseButtonMask.Left; }
                        if (msg == NativeMethods.WindowMessage.RightButtonUp) { isMouseRButtonDown = false; currentButtonMask &= ~(int)MouseButtonMask.Right; }
                        if (msg == NativeMethods.WindowMessage.MiddleButtonUp) { isMouseMButtonDown = false; currentButtonMask &= ~(int)MouseButtonMask.Middle; }

                        // Release the capture if no mouse buttons are down
                        if (!isMouseLButtonDown && !isMouseMButtonDown && !isMouseRButtonDown)
                        {
                            NativeMethods.ReleaseCapture();
                        }
                    }
                    break;

                // Handle the mouse wheel
                case NativeMethods.WindowMessage.MouseWheel:
                    mouseWheelDelta = NativeMethods.HiWord((uint)wParam.ToInt32()) / 120;
                    break;
            }

            return false;
        }


        public virtual void Reset()
        {
            SetViewParameters(defaultEye, defaultLookAt);
        }

        public unsafe virtual void SetViewParameters(Vector3 eyePt, Vector3 lookAtPt)
        {
            // Store the data
            defaultEye = eye = eyePt;
            defaultLookAt = lookAt = lookAtPt;

            // Calculate the view matrix
            viewMatrix = Matrix.LookAtLeftHanded(eye, lookAt, UpDirection);

            // Get the inverted matrix
            Matrix inverseView = Matrix.Invert(viewMatrix);

            // The axis basis vectors and camera position are stored inside the 
            // position matrix in the 4 rows of the camera's world matrix.
            // To figure out the yaw/pitch of the camera, we just need the Z basis vector
            Vector3* pZBasis = (Vector3*)&inverseView.M31;
            cameraYawAngle = (float)Math.Atan2(pZBasis->X, pZBasis->Z);
            float len = (float)Math.Sqrt(pZBasis->Z * pZBasis->Z + pZBasis->X * pZBasis->X);
            cameraPitchAngle = -(float)Math.Atan2(pZBasis->Y, len);
        }

        public virtual void SetProjectionParameters(float fov, float aspect, float near, float far)
        {
            // Set attributes for the projection matrix
            fieldOfView = fov;
            aspectRatio = aspect;
            nearPlane = near;
            farPlane = far;

            projMatrix = Matrix.PerspectiveFieldOfViewLeftHanded(fov, aspect, near, far);
        }

        protected void UpdateMouseDelta(float elapsedTime)
        {
            // Get the current mouse position
            System.Drawing.Point current = System.Windows.Forms.Cursor.Position;

            // Calculate how far it's moved since the last frame
            System.Drawing.Point delta = new System.Drawing.Point(current.X - lastMousePosition.X,
                current.Y - lastMousePosition.Y);

            // Record the current position for next time
            lastMousePosition = current;

            if (isResetCursorAfterMove)
            {
                // Set position of camera to center of desktop, 
                // so it always has room to move.  This is very useful
                // if the cursor is hidden.  If this isn't done and cursor is hidden, 
                // then invisible cursor will hit the edge of the screen 
                // and the user can't tell what happened
                System.Windows.Forms.Screen activeScreen = System.Windows.Forms.Screen.PrimaryScreen;
                System.Drawing.Point center = new System.Drawing.Point(activeScreen.Bounds.Width / 2,
                    activeScreen.Bounds.Height / 2);
                System.Windows.Forms.Cursor.Position = center;
                lastMousePosition = center;
            }

            // Smooth the relative mouse data over a few frames so it isn't 
            // jerky when moving slowly at low frame rates.
            float percentOfNew = 1.0f / framesToSmoothMouseData;
            float percentOfOld = 1.0f - percentOfNew;
            mouseDelta.X = mouseDelta.X * percentOfNew + delta.X * percentOfNew;
            mouseDelta.Y = mouseDelta.Y * percentOfNew + delta.Y * percentOfNew;

            rotationVelocity = mouseDelta * rotationScaler;
        }

        protected void UpdateVelocity(float elapsedTime)
        {
            Vector3 accel = Vector3.Empty;

            if (isEnablePositionMovement)
            {
                // Update acceleration vector based on keyboard state
                if (keys[(int)CameraKeys.MoveForward])
                    accel.Z += 1.0f;
                if (keys[(int)CameraKeys.MoveBackward])
                    accel.Z -= 1.0f;
                if (isEnableYAxisMovement)
                {
                    if (keys[(int)CameraKeys.MoveUp])
                        accel.Y += 1.0f;
                    if (keys[(int)CameraKeys.MoveDown])
                        accel.Y -= 1.0f;
                }
                if (keys[(int)CameraKeys.StrafeRight])
                    accel.X += 1.0f;
                if (keys[(int)CameraKeys.StrafeLeft])
                    accel.X -= 1.0f;
            }
            // Normalize vector so if moving 2 dirs (left & forward), 
            // the camera doesn't move faster than if moving in 1 dir
            accel.Normalize();
            // Scale the acceleration vector
            accel *= moveScaler;

            if (isMovementDrag)
            {
                // Is there any acceleration this frame?
                if (accel.LengthSquared() > 0)
                {
                    // If so, then this means the user has pressed a movement key
                    // so change the velocity immediately to acceleration 
                    // upon keyboard input.  This isn't normal physics
                    // but it will give a quick response to keyboard input
                    velocity = accel;
                    dragTimer = totalDragTimeToZero;
                    velocityDrag = accel * (1 / dragTimer);
                }
                else
                {
                    // If no key being pressed, then slowly decrease velocity to 0
                    if (dragTimer > 0)
                    {
                        velocity -= (velocityDrag * elapsedTime);
                        dragTimer -= elapsedTime;
                    }
                    else
                    {
                        // Zero velocity
                        velocity = Vector3.Empty;
                    }
                }
            }
            else
            {
                // No drag, so immediately change the velocity
                velocity = accel;
            }
        }

        protected void ConstrainToBoundary(ref Vector3 v)
        {
            // Constrain vector to a bounding box 
            v.X = Math.Max(v.X, minBoundary.X);
            v.Y = Math.Max(v.Y, minBoundary.Y);
            v.Z = Math.Max(v.Z, minBoundary.Z);

            v.X = Math.Min(v.X, maxBoundary.X);
            v.Y = Math.Min(v.Y, maxBoundary.Y);
            v.Z = Math.Min(v.Z, maxBoundary.Z);

        }
    }

    public class FirstPersonCamera : Camera
    {
        // Mask to determine which button to enable for rotation
        protected int activeButtonMask = (int)(MouseButtonMask.Left | MouseButtonMask.Middle | MouseButtonMask.Right);
        // World matrix of the camera (inverse of the view matrix)
        protected Matrix cameraWorld;

        public override void FrameMove(float elapsedTime)
        {
            // Reset the camera if necessary
            if (keys[(int)CameraKeys.Reset])
                Reset();

            // Get the mouse movement (if any) if the mouse buttons are down
            if ((activeButtonMask & currentButtonMask) != 0)
                UpdateMouseDelta(elapsedTime);

            // Get amount of velocity based on the keyboard input and drag (if any)
            UpdateVelocity(elapsedTime);

            // Simple euler method to calculate position delta
            Vector3 posDelta = velocity * elapsedTime;

            // If rotating the camera 
            if ((activeButtonMask & currentButtonMask) != 0)
            {
                // Update the pitch & yaw angle based on mouse movement
                float yawDelta = rotationVelocity.X;
                float pitchDelta = rotationVelocity.Y;

                // Invert pitch if requested
                if (isInvertPitch)
                    pitchDelta = -pitchDelta;

                cameraPitchAngle += pitchDelta;
                cameraYawAngle += yawDelta;

                // Limit pitch to straight up or straight down
                cameraPitchAngle = Math.Max(-(float)Math.PI / 2.0f, cameraPitchAngle);
                cameraPitchAngle = Math.Min(+(float)Math.PI / 2.0f, cameraPitchAngle);
            }

            // Make a rotation matrix based on the camera's yaw & pitch
            Matrix cameraRotation = Matrix.RotationYawPitchRoll(cameraYawAngle, cameraPitchAngle, 0);

            // Transform vectors based on camera's rotation matrix
            Vector3 localUp = new Vector3(0, 1, 0);
            Vector3 localAhead = new Vector3(0, 0, 1);
            Vector3 worldUp = Vector3.TransformCoordinate(localUp, cameraRotation);
            Vector3 worldAhead = Vector3.TransformCoordinate(localAhead, cameraRotation);

            // Transform the position delta by the camera's rotation 
            Vector3 posDeltaWorld = Vector3.TransformCoordinate(posDelta, cameraRotation);
            if (!isEnableYAxisMovement)
                posDeltaWorld.Y = 0.0f;

            // Move the eye position 
            eye += posDeltaWorld;
            if (isClipToBoundary)
                ConstrainToBoundary(ref eye);

            // Update the lookAt position based on the eye position 
            lookAt = eye + worldAhead;

            // Update the view matrix
            viewMatrix = Matrix.LookAtLeftHanded(eye, lookAt, worldUp);
            cameraWorld = Matrix.Invert(viewMatrix);
        }

        public void SetRotationButtons(bool left, bool middle, bool right)
        {
            activeButtonMask = (left ? (int)MouseButtonMask.Left : 0) |
                (middle ? (int)MouseButtonMask.Middle : 0) |
                (right ? (int)MouseButtonMask.Right : 0);
        }
    }

    public class ModelViewerCamera : Camera
    {
        #region Instance Data
        protected ArcBall worldArcball = new ArcBall();
        protected ArcBall viewArcball = new ArcBall();
        protected Vector3 modelCenter;
        protected Matrix lastModelRotation; // Last arcball rotation matrix for model 
        protected Matrix lastCameraRotation; // Last rotation matrix for camera
        protected Matrix modelRotation; // Rotation matrix of model
        protected Matrix world; // World Matrix of model

        protected int rotateModelButtonMask;
        protected int zoomButtonMask;
        protected int rotateCameraButtonMask;

        protected bool isPitchLimited;
        protected float radius; // Distance from the camera to model 
        protected float defaultRadius; // Distance from the camera to model 
        protected float minRadius; // Min radius
        protected float maxRadius; // Max radius
        protected bool attachCameraToModel;
        #endregion

        #region Simple Properties/Set Methods
        public float MinimumRadius { get { return minRadius; } set { minRadius = value; } }
        public float MaximumRadius { get { return maxRadius; } set { maxRadius = value; } }
        public Matrix WorldMatrix { get { return world; } }
        public void SetWorldQuat(Quaternion q) { worldArcball.CurrentQuaternion = q; }
        public void SetViewQuat(Quaternion q) { viewArcball.CurrentQuaternion = q; }
        public void SetIsPitchLimited(bool limit) { isPitchLimited = limit; }
        public void SetModelCenter(Vector3 c) { modelCenter = c; }
        public void SetRadius(float r, float min, float max) { radius = defaultRadius = r; minRadius = min; maxRadius = max; }
        public void SetRadius(float r) { defaultRadius = r; minRadius = 1.0f; maxRadius = float.MaxValue; }
        public void SetWindow(int w, int h, float r) { worldArcball.SetWindow(w, h, r); viewArcball.SetWindow(w, h, r); }
        public void SetWindow(int w, int h) { worldArcball.SetWindow(w, h, 0.9f); viewArcball.SetWindow(w, h, 0.9f); }
        public void SetButtonMasks(int rotateModel, int zoom, int rotateCamera) { rotateCameraButtonMask = rotateCamera; zoomButtonMask = zoom; rotateModelButtonMask = rotateModel; }
        public bool IsAttachedToModel { get { return attachCameraToModel; } set { attachCameraToModel = value; } }
        #endregion

        public ModelViewerCamera()
        {
            world = Matrix.Identity;
            modelRotation = Matrix.Identity;
            lastModelRotation = Matrix.Identity;
            lastCameraRotation = Matrix.Identity;
            modelCenter = Vector3.Empty;
            radius = 5.0f;
            defaultRadius = 5.0f;
            minRadius = 1.0f;
            maxRadius = float.MaxValue;
            isPitchLimited = false;
            isEnablePositionMovement = false;
            attachCameraToModel = false;

            // Set button masks
            rotateModelButtonMask = (int)MouseButtonMask.Left;
            zoomButtonMask = (int)MouseButtonMask.Wheel;
            rotateCameraButtonMask = (int)MouseButtonMask.Right;
        }

        public unsafe override void FrameMove(float elapsedTime)
        {
            // Reset the camera if necessary
            if (keys[(int)CameraKeys.Reset])
                Reset();

            // Get the mouse movement (if any) if the mouse buttons are down
            if (currentButtonMask != 0)
                UpdateMouseDelta(elapsedTime);

            // Get amount of velocity based on the keyboard input and drag (if any)
            UpdateVelocity(elapsedTime);

            // Simple euler method to calculate position delta
            Vector3 posDelta = velocity * elapsedTime;

            // Change the radius from the camera to the model based on wheel scrolling
            if ((mouseWheelDelta != 0) && (zoomButtonMask == (int)MouseButtonMask.Wheel))
                radius -= mouseWheelDelta * radius * 0.1f;
            radius = Math.Min(maxRadius, radius);
            radius = Math.Max(minRadius, radius);
            mouseWheelDelta = 0;

            // Get the inverse of the arcball's rotation matrix
            Matrix cameraRotation = Matrix.Invert(viewArcball.RotationMatrix);

            // Transform vectors based on camera's rotation matrix
            Vector3 localUp = new Vector3(0, 1, 0);
            Vector3 localAhead = new Vector3(0, 0, 1);
            Vector3 worldUp = Vector3.TransformCoordinate(localUp, cameraRotation);
            Vector3 worldAhead = Vector3.TransformCoordinate(localAhead, cameraRotation);

            // Transform the position delta by the camera's rotation 
            Vector3 posDeltaWorld = Vector3.TransformCoordinate(posDelta, cameraRotation);

            // Move the lookAt position 
            lookAt += posDeltaWorld;
            if (isClipToBoundary)
                ConstrainToBoundary(ref lookAt);

            // Update the eye point based on a radius away from the lookAt position
            eye = lookAt - worldAhead * radius;

            // Update the view matrix
            viewMatrix = Matrix.LookAtLeftHanded(eye, lookAt, worldUp);
            Matrix invView = Matrix.Invert(viewMatrix);
            invView.M41 = invView.M42 = invView.M43 = 0;
            Matrix modelLastRotInv = Matrix.Invert(lastModelRotation);

            // Accumulate the delta of the arcball's rotation in view space.
            // Note that per-frame delta rotations could be problematic over long periods of time.
            Matrix localModel = worldArcball.RotationMatrix;
            modelRotation *= viewMatrix * modelLastRotInv * localModel * invView;
            if (viewArcball.IsBeingDragged && attachCameraToModel && !keys[(int)CameraKeys.ControlDown])
            {
                // Attah camera to model by inverse of the model rotation
                Matrix cameraRotInv = Matrix.Invert(lastCameraRotation);
                Matrix delta = cameraRotInv * cameraRotation; // local to world matrix
                modelRotation *= delta;
            }
            lastCameraRotation = cameraRotation;
            lastModelRotation = localModel;

            // Since we're accumulating delta rotations, we need to orthonormalize 
            // the matrix to prevent eventual matrix skew
            fixed (void* pxBasis = &modelRotation.M11)
            {
                fixed (void* pyBasis = &modelRotation.M21)
                {
                    fixed (void* pzBasis = &modelRotation.M31)
                    {
                        UnsafeNativeMethods.Vector3.Normalize((Vector3*)pxBasis, (Vector3*)pxBasis);
                        UnsafeNativeMethods.Vector3.Cross((Vector3*)pyBasis, (Vector3*)pzBasis, (Vector3*)pxBasis);
                        UnsafeNativeMethods.Vector3.Normalize((Vector3*)pyBasis, (Vector3*)pyBasis);
                        UnsafeNativeMethods.Vector3.Cross((Vector3*)pzBasis, (Vector3*)pxBasis, (Vector3*)pyBasis);
                    }
                }
            }

            // Translate the rotation matrix to the same position as the lookAt position
            modelRotation.M41 = lookAt.X;
            modelRotation.M42 = lookAt.Y;
            modelRotation.M43 = lookAt.Z;

            // Translate world matrix so its at the center of the model
            Matrix trans = Matrix.Translation(-modelCenter.X, -modelCenter.Y, -modelCenter.Z);
            world = trans * modelRotation;
        }

        public override void Reset()
        {
            base.Reset();
            world = Matrix.Identity;
            modelRotation = Matrix.Identity;
            lastModelRotation = Matrix.Identity;
            lastCameraRotation = Matrix.Identity;
            radius = defaultRadius;
            worldArcball.Reset();
            viewArcball.Reset();
        }

        public override void SetViewParameters(Vector3 eyePt, Vector3 lookAtPt)
        {
            // Call base first
            base.SetViewParameters(eyePt, lookAtPt);

            // Propogate changes to the member arcball
            Matrix rotation = Matrix.LookAtLeftHanded(eyePt, lookAtPt, UpDirection);
            viewArcball.CurrentQuaternion = Quaternion.RotationMatrix(rotation);

            // Set the radius according to the distance
            Vector3 eyeToPoint = lookAtPt - eyePt;
            SetRadius(eyeToPoint.Length());
        }

        public override bool HandleMessages(IntPtr hWnd, NativeMethods.WindowMessage msg, IntPtr wParam, IntPtr lParam)
        {
            // Call base first
            base.HandleMessages(hWnd, msg, wParam, lParam);

            if (((msg == NativeMethods.WindowMessage.LeftButtonDown || msg == NativeMethods.WindowMessage.LeftButtonDoubleClick) && ((rotateModelButtonMask & (int)MouseButtonMask.Left) != 0)) ||
                ((msg == NativeMethods.WindowMessage.RightButtonDown || msg == NativeMethods.WindowMessage.RightButtonDoubleClick) && ((rotateModelButtonMask & (int)MouseButtonMask.Right) != 0)) ||
                ((msg == NativeMethods.WindowMessage.MiddleButtonDown || msg == NativeMethods.WindowMessage.MiddleButtonDoubleClick) && ((rotateModelButtonMask & (int)MouseButtonMask.Middle) != 0)))
            {
                // Current mouse position
                short mouseX = NativeMethods.LoWord((uint)lParam.ToInt32());
                short mouseY = NativeMethods.HiWord((uint)lParam.ToInt32());
                worldArcball.OnBegin(mouseX, mouseY);
            }
            if (((msg == NativeMethods.WindowMessage.LeftButtonDown || msg == NativeMethods.WindowMessage.LeftButtonDoubleClick) && ((rotateCameraButtonMask & (int)MouseButtonMask.Left) != 0)) ||
                ((msg == NativeMethods.WindowMessage.RightButtonDown || msg == NativeMethods.WindowMessage.RightButtonDoubleClick) && ((rotateCameraButtonMask & (int)MouseButtonMask.Right) != 0)) ||
                ((msg == NativeMethods.WindowMessage.MiddleButtonDown || msg == NativeMethods.WindowMessage.MiddleButtonDoubleClick) && ((rotateCameraButtonMask & (int)MouseButtonMask.Middle) != 0)))
            {
                // Current mouse position
                short mouseX = NativeMethods.LoWord((uint)lParam.ToInt32());
                short mouseY = NativeMethods.HiWord((uint)lParam.ToInt32());
                viewArcball.OnBegin(mouseX, mouseY);
            }
            if (msg == NativeMethods.WindowMessage.MouseMove)
            {
                // Current mouse position
                short mouseX = NativeMethods.LoWord((uint)lParam.ToInt32());
                short mouseY = NativeMethods.HiWord((uint)lParam.ToInt32());
                worldArcball.OnMove(mouseX, mouseY);
                viewArcball.OnMove(mouseX, mouseY);
            }

            if ((msg == NativeMethods.WindowMessage.LeftButtonUp) && ((rotateModelButtonMask & (int)MouseButtonMask.Left) != 0) ||
                (msg == NativeMethods.WindowMessage.RightButtonUp) && ((rotateModelButtonMask & (int)MouseButtonMask.Right) != 0) ||
                (msg == NativeMethods.WindowMessage.MiddleButtonUp) && ((rotateModelButtonMask & (int)MouseButtonMask.Middle) != 0))
            {
                worldArcball.OnEnd();
            }

            if ((msg == NativeMethods.WindowMessage.LeftButtonUp) && ((rotateCameraButtonMask & (int)MouseButtonMask.Left) != 0) ||
                (msg == NativeMethods.WindowMessage.RightButtonUp) && ((rotateCameraButtonMask & (int)MouseButtonMask.Right) != 0) ||
                (msg == NativeMethods.WindowMessage.MiddleButtonUp) && ((rotateCameraButtonMask & (int)MouseButtonMask.Middle) != 0))
            {
                viewArcball.OnEnd();
            }

            return false;
        }
    }
    #endregion

    #region Text Helper
    public struct TextHelper
    {
        private Font textFont; // Used to draw the text
        private Sprite textSprite; // Used to cache the drawn text
        private int color; // Color to draw the text
        private System.Drawing.Point point; // Where to draw the text
        private int lineHeight; // Height of the lines

        public TextHelper(Font f, Sprite s, int l)
        {
            textFont = f;
            textSprite = s;
            lineHeight = l;
            color = unchecked((int)0xffffffff);
            point = System.Drawing.Point.Empty;
        }

        public void DrawStringLine(string text)
        {
            if (textFont == null)
            {
                throw new InvalidOperationException("You cannot draw text.  There is no font object.");
            }
            // Create the rectangle to draw to
            System.Drawing.Rectangle rect = new System.Drawing.Rectangle(point, System.Drawing.Size.Empty);
            textFont.DrawString(textSprite, text, rect, DrawStringFormat.NoClip, color);

            // Increase the line height
            point.Y += lineHeight;
        }

        public void DrawStringLine(string text, params object[] args)
        {
            // Simply format the string and pass it on
            DrawStringLine(string.Format(text, args));
        }

        public void SetInsertionPoint(System.Drawing.Point p) { point = p; }
        public void SetInsertionPoint(int x, int y) { point.X = x; point.Y = y; }

        public void SetForegroundColor(int c) { color = c; }
        public void SetForegroundColor(System.Drawing.Color c) { color = c.ToArgb(); }

        public void Begin()
        {
            if (textSprite != null)
            {
                textSprite.Begin(SpriteFlags.AlphaBlend | SpriteFlags.SortTexture);
            }
        }

        public void End()
        {
            if (textSprite != null)
            {
                textSprite.End();
            }
        }
    }
    #endregion

    #region Utility
    public class Utility
    {
        // Constants for search folders
        private const string CurrentFolder = @".\";
        private const string MediaPath = @"Media\";

        // Typical folder locations
        //      .\
        //      ..\
        //      ..\..\
        //      %EXE_DIR%\
        //      %EXE_DIR%\..\
        //      %EXE_DIR%\..\..\
        //      %EXE_DIR%\..\%EXE_NAME%
        //      %EXE_DIR%\..\..\%EXE_NAME%
        //      DXSDK media path
        private static readonly string[] TypicalFolders = new string[] { CurrentFolder, @"..\",
                                                                               @"..\..\", @"{0}\", @"{0}\..\", @"{0}\..\..\", @"{0}\..\{1}\", @"{0}\..\..\{1}\" };
        private Utility() { /* Private Constructor */ }

        public static string FindMediaFile(string filename)
        {
            // Find out the executing assembly information
            System.Reflection.Assembly executingAssembly = System.Reflection.Assembly.GetExecutingAssembly();
            // Now check the typical folders, before you can do that you'll need to get 
            // the executable name
            string exeName = System.IO.Path.GetFileNameWithoutExtension(executingAssembly.Location);
            // And the executable folder
            string exeFolder = System.IO.Path.GetDirectoryName(executingAssembly.Location);

            string filePath;
            // Now you can search the typical folders
            if (SearchTypicalFolders(filename, exeFolder, exeName, out filePath))
            {
                return filePath;
            }

            // The file wasn't found again, search the folders with \media on them
            // Now you can search the typical folders
            if (SearchTypicalFolders(filename + MediaPath, exeFolder, exeName, out filePath))
            {
                return filePath;
            }

            // We still haven't found the file yet, we should search the parents folders now
            if (SearchParentFolders(filename, CurrentFolder, "", out filePath))
            {
                return filePath;
            }
            // We still haven't found the file yet, now search from the exe folder
            if (SearchParentFolders(filename, exeFolder, exeName, out filePath))
            {
                return filePath;
            }

            // We still haven't found the file yet, we should search the parents folders now, but append media
            if (SearchParentFolders(filename, CurrentFolder, MediaPath, out filePath))
            {
                return filePath;
            }
            // We still haven't found the file yet, now search from the exe folder and append media
            if (SearchParentFolders(filename, exeFolder, AppendDirectorySeparator(exeName) + MediaPath, out filePath))
            {
                return filePath;
            }


            // We still haven't found the file yet, the built samples are prefixed with 'csw', so see if that's the case
            if (exeName.ToLower().StartsWith("csw"))
            {
                // Build the new exe name by stripping off the 'csw' prefix and doing the searches again
                string newExeName = exeName.Substring(3, exeName.Length - 3);
                if (SearchParentFolders(filename, exeFolder, newExeName, out filePath))
                {
                    return filePath;
                }
                // We still haven't found the file yet, now search from the exe folder and append media
                if (SearchParentFolders(filename, exeFolder, AppendDirectorySeparator(newExeName) + MediaPath, out filePath))
                {
                    return filePath;
                }
            }

            // Before throwing an exception, girst check to see if the file exists as is
            if (File.Exists(filename))
            {
                return filename;
            }

            throw new MediaNotFoundException();
        }

        private static bool SearchTypicalFolders(string filename, string exeFolder, string exeName, out string fullPath)
        {
            // First scan through each typical folder and see if we found the file
            for (int i = 0; i < TypicalFolders.Length; i++)
            {
                try
                {
                    FileInfo info = new FileInfo(string.Format(TypicalFolders[i], exeFolder, exeName) + filename);
                    if (info.Exists)
                    {
                        fullPath = info.FullName;
                        return true;
                    }
                }
                catch (NotSupportedException)
                {
                    // This exception will be fired if the filename is not supported
                    continue;
                }
            }

            // We never found any of the files
            fullPath = string.Empty;
            return false;
        }

        private static bool SearchParentFolders(string filename, string rootNode, string leafName, out string fullPath)
        {
            // Set the out parameter first
            fullPath = string.Empty;
            try
            {
                // Search the root node first
                FileInfo info = new FileInfo(AppendDirectorySeparator(rootNode) + AppendDirectorySeparator(leafName) + filename);
                if (info.Exists)
                {
                    fullPath = info.FullName;
                    return true;
                }
            }
            catch (NotSupportedException)
            {
                // The arguments passed in are not supported, fail now
                return false;
            }

            // Are we in the root yet?
            DirectoryInfo dir = new DirectoryInfo(rootNode);
            if (dir.Parent != null)
            {
                return SearchParentFolders(filename, dir.Parent.FullName, leafName, out fullPath);
            }
            else
            {
                // We never found any of the files
                return false;
            }
        }

        public static string AppendDirectorySeparator(string pathName)
        {
            if (!pathName.EndsWith(@"\"))
                return pathName + @"\";

            return pathName;
        }

        public static Matrix GetCubeMapViewMatrix(CubeMapFace face)
        {
            Vector3 vEyePt = new Vector3(0.0f, 0.0f, 0.0f);
            Vector3 vLookDir = new Vector3();
            Vector3 vUpDir = new Vector3();

            switch (face)
            {
                case CubeMapFace.PositiveX:
                    vLookDir = new Vector3(1.0f, 0.0f, 0.0f);
                    vUpDir = new Vector3(0.0f, 1.0f, 0.0f);
                    break;
                case CubeMapFace.NegativeX:
                    vLookDir = new Vector3(-1.0f, 0.0f, 0.0f);
                    vUpDir = new Vector3(0.0f, 1.0f, 0.0f);
                    break;
                case CubeMapFace.PositiveY:
                    vLookDir = new Vector3(0.0f, 1.0f, 0.0f);
                    vUpDir = new Vector3(0.0f, 0.0f, -1.0f);
                    break;
                case CubeMapFace.NegativeY:
                    vLookDir = new Vector3(0.0f, -1.0f, 0.0f);
                    vUpDir = new Vector3(0.0f, 0.0f, 1.0f);
                    break;
                case CubeMapFace.PositiveZ:
                    vLookDir = new Vector3(0.0f, 0.0f, 1.0f);
                    vUpDir = new Vector3(0.0f, 1.0f, 0.0f);
                    break;
                case CubeMapFace.NegativeZ:
                    vLookDir = new Vector3(0.0f, 0.0f, -1.0f);
                    vUpDir = new Vector3(0.0f, 1.0f, 0.0f);
                    break;
            }

            // Set the view transform for this cubemap surface
            Matrix matView = Matrix.LookAtLeftHanded(vEyePt, vLookDir, vUpDir);
            return matView;
        }
        public static Matrix GetCubeMapViewMatrix(int face) { return GetCubeMapViewMatrix((CubeMapFace)face); }

        private static bool firstTime = true;
        public static void DisplaySwitchingToRefWarning(Framework framework, string sampleTitle)
        {
            if (framework.IsShowingMsgBoxOnError)
            {
                // Read the registry key to see if the warning should be skipped
                int skipWarning = 0;
                try
                {
                    using (Microsoft.Win32.RegistryKey key = Microsoft.Win32.Registry.CurrentUser.CreateSubKey(SwitchRefDialog.KeyLocation))
                    {
                        skipWarning = (int)key.GetValue(SwitchRefDialog.KeyValueName, (int)0);
                    }
                }
                catch { } // Ignore any errors
                if ((skipWarning == 0) && (firstTime)) // Show dialog
                {
                    firstTime = false;
                    using (SwitchRefDialog dialog = new SwitchRefDialog(sampleTitle))
                    {
                        System.Windows.Forms.Application.Run(dialog);
                        if (dialog.DialogResult == System.Windows.Forms.DialogResult.Cancel)
                        {
                            // Shutdown the application
                            framework.Dispose();
                        }
                    }
                }
            }
        }
    }
    #endregion

    #region Widgets

    #region Direction Widget
    public class DirectionWidget
    {
        #region Class level data (Instance/Static)
        // Instance members
        private float widgetRadius = 1.0f;
        private ArcBall arc = new ArcBall();
        private Vector3 defaultDir = new Vector3(0, 1, 0);
        private Vector3 currentDir = new Vector3(0, 1, 0);
        private Matrix viewMatrix = Matrix.Identity;
        private Matrix rotation = Matrix.Identity;
        private Matrix rotationSnapshot = Matrix.Identity;
        private MouseButtonMask rotateMask = MouseButtonMask.Right;

        // Static members
        private static Device device = null;
        private static Effect effect = null;
        private static Mesh mesh = null;
        #endregion

        #region Properties
        public float Radius { get { return widgetRadius; } set { widgetRadius = value; } }
        public Vector3 LightDirection { get { return currentDir; } set { currentDir = defaultDir = value; } }
        public bool IsBeingDragged { get { return arc.IsBeingDragged; } }
        public MouseButtonMask RotateButtonMask { get { return rotateMask; } set { rotateMask = value; } }
        #endregion

        #region Device handlers
        public static void OnCreateDevice(Device device)
        {
            // Store the device
            DirectionWidget.device = device;

            // Read the effect file
            string path = Utility.FindMediaFile("UI\\DXUTShared.fx");

            // If this fails, there should be debug output as to 
            // why the .fx file failed to compile (assuming you have dbmon running).
            // If you do not, you can turn on unmanaged debugging for this project.
            effect = Effect.FromFile(device, path, null, null, null, ShaderFlags.NotCloneable, null);

            // Load the mesh with D3DX and get back a Mesh.  For this
            // sample we'll ignore the X file's embedded materials since we know 
            // exactly the model we're loading.  See the mesh samples such as
            // "OptimizedMesh" for a more generic mesh loading example.
            path = Utility.FindMediaFile("UI\\arrow.x");
            mesh = new Mesh(device, path, MeshFlags.Managed, null, null, null);

            // Optimize the mesh for this graphics card's vertex cache 
            // so when rendering the mesh's triangle list the vertices will 
            // cache hit more often so it won't have to re-execute the vertex shader 
            // on those vertices so it will improve perf.     
            Microsoft.DirectX.Generic.GraphicsBuffer<int> adj = new Microsoft.DirectX.Generic.GraphicsBuffer<int>(mesh.FaceCount * 3);
            mesh.GenerateAdjacency(1e-6f, adj);
            mesh.OptimizeInPlace(MeshFlags.OptimizeVertexCache, adj);
        }

        public void OnResetDevice(SurfaceDescription desc)
        {
            arc.SetWindow(desc.Width, desc.Height);
        }

        public static void OnLostDevice()
        {
            if (effect != null)
                effect.OnLostDevice();
        }

        public static void OnDestroyDevice()
        {
            if (effect != null)
                effect.Dispose();
            if (mesh != null)
                mesh.Dispose();
            effect = null;
            mesh = null;
        }
        #endregion

        public bool HandleMessages(IntPtr hWnd, NativeMethods.WindowMessage msg, IntPtr wParam, IntPtr lParam)
        {
            // Current mouse position
            short mouseX = NativeMethods.LoWord((uint)lParam.ToInt32());
            short mouseY = NativeMethods.HiWord((uint)lParam.ToInt32());

            switch (msg)
            {
                case NativeMethods.WindowMessage.LeftButtonDown:
                case NativeMethods.WindowMessage.MiddleButtonDown:
                case NativeMethods.WindowMessage.RightButtonDown:
                    {
                        if (((rotateMask & MouseButtonMask.Left) == MouseButtonMask.Left && msg == NativeMethods.WindowMessage.LeftButtonDown) ||
                            ((rotateMask & MouseButtonMask.Right) == MouseButtonMask.Right && msg == NativeMethods.WindowMessage.RightButtonDown) ||
                            ((rotateMask & MouseButtonMask.Middle) == MouseButtonMask.Middle && msg == NativeMethods.WindowMessage.MiddleButtonDown))
                        {
                            arc.OnBegin(mouseX, mouseY);
                            NativeMethods.SetCapture(hWnd);
                        }
                        return true;
                    }
                case NativeMethods.WindowMessage.MouseMove:
                    {
                        if (arc.IsBeingDragged)
                        {
                            arc.OnMove(mouseX, mouseY);
                            UpdateLightDirection();
                        }
                        return true;
                    }
                case NativeMethods.WindowMessage.LeftButtonUp:
                case NativeMethods.WindowMessage.RightButtonUp:
                case NativeMethods.WindowMessage.MiddleButtonUp:
                    {
                        if (((rotateMask & MouseButtonMask.Left) == MouseButtonMask.Left && msg == NativeMethods.WindowMessage.LeftButtonUp) ||
                            ((rotateMask & MouseButtonMask.Right) == MouseButtonMask.Right && msg == NativeMethods.WindowMessage.RightButtonUp) ||
                            ((rotateMask & MouseButtonMask.Middle) == MouseButtonMask.Middle && msg == NativeMethods.WindowMessage.MiddleButtonUp))
                        {
                            arc.OnEnd();
                            NativeMethods.ReleaseCapture();
                        }

                        UpdateLightDirection();
                        return true;
                    }
            }

            // Didn't handle the message
            return false;
        }

        private unsafe void UpdateLightDirection()
        {
            Matrix invView = Matrix.Invert(viewMatrix);
            invView.M41 = invView.M42 = invView.M43 = 0;

            Matrix lastRotationInv = Matrix.Invert(rotationSnapshot);
            Matrix rot = arc.RotationMatrix;
            rotationSnapshot = rot;

            // Accumulate the delta of the arcball's rotation in view space.
            // Note that per-frame delta rotations could be problematic over long periods of time.
            rotation *= (viewMatrix * lastRotationInv * rot * invView);

            // Since we're accumulating delta rotations, we need to orthonormalize 
            // the matrix to prevent eventual matrix skew
            fixed (void* pxBasis = &rotation.M11)
            {
                fixed (void* pyBasis = &rotation.M21)
                {
                    fixed (void* pzBasis = &rotation.M31)
                    {
                        UnsafeNativeMethods.Vector3.Normalize((Vector3*)pxBasis, (Vector3*)pxBasis);
                        UnsafeNativeMethods.Vector3.Cross((Vector3*)pyBasis, (Vector3*)pzBasis, (Vector3*)pxBasis);
                        UnsafeNativeMethods.Vector3.Normalize((Vector3*)pyBasis, (Vector3*)pyBasis);
                        UnsafeNativeMethods.Vector3.Cross((Vector3*)pzBasis, (Vector3*)pxBasis, (Vector3*)pyBasis);
                    }
                }
            }

            // Transform the default direction vector by the light's rotation matrix
            currentDir = Vector3.TransformNormal(defaultDir, rotation);
        }

        public unsafe void OnRender(ColorValue color, Matrix view, Matrix proj, Vector3 eye)
        {
            // Store the view matrix
            viewMatrix = view;

            // Render the light arrows so the user can visually see the light direction
            effect.Technique = "RenderWith1LightNoTexture";
            effect.SetValue("g_MaterialDiffuseColor", color);
            Vector3 eyePt = Vector3.Normalize(eye);

            // Set the light direction value
            effect.SetValue("g_LightDir", &eyePt, sizeof(Vector3));

            // Rotate arrow model to point towards origin
            Vector3 at = Vector3.Empty;
            Vector3 up = new Vector3(0, 1, 0);
            Matrix rotateB = Matrix.RotationX((float)Math.PI);
            Matrix rotateA = Matrix.LookAtLeftHanded(currentDir, at, up);
            rotateA.Invert();
            Matrix rotate = rotateB * rotateA;
            Vector3 l = currentDir * widgetRadius * 1.0f;
            Matrix trans = Matrix.Translation(l);
            Matrix scale = Matrix.Scaling(widgetRadius * 0.2f, widgetRadius * 0.2f, widgetRadius * 0.2f);

            Matrix world = rotate * scale * trans;
            Matrix worldViewProj = world * viewMatrix * proj;

            effect.SetValue("g_mWorldViewProjection", worldViewProj);
            effect.SetValue("g_mWorld", world);

            // Render the arrows
            for (int subset = 0; subset < 2; subset++)
            {
                int passes = effect.Begin(0);
                for (int pass = 0; pass < passes; pass++)
                {
                    effect.BeginPass(pass);
                    mesh.DrawSubset(subset);
                    effect.EndPass();
                }
                effect.End();
            }

        }
    }
    #endregion

    #endregion
}

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