title: How to control stereo-frames separately with C#? (NVIDIA 3D shutter glasses)
body: <p>I’m trying to make a very simple application which would display different images on each eye. I have Asus VG236H monitor and NVIDIA 3D Vision kit, the stereo 3D shutter glasses. The I’m using C#, .NET Framework 2.0, DirectX 9 (Managed Direct X) and Visual Studio 2008. I have been searching high and low for examples and tutorials, have actually found a couple and based those I have created the program but for some reason I can’t get it working. </p>
  
  <p>When looking for examples how to display different images for each eye, many people keep referring to the NVIDIA presentation at GDC 09 (the famous GDC09-3DVision-The_In_and_Out.pdf document) and the pages 37-40. My code is mainly constructed based on that example:</p>
  
  <ol>
  <li>I'm loading two textures (Red.png and Blue.png) on surface (_imageLeft and _imageRight), in function LoadSurfaces()</li>
  <li>Set3D() function puts those two images side-by-side to one bigger image which has the size of 2x Screen width and Screen height + 1 (_imageBuf).</li>
  <li>Set3D() function continues by appending the stereo signature on the last row.</li>
  <li>OnPaint()-function takes the back buffer (_backBuf) and copies the content of the combined image (_imageBuf) to it.</li>
  </ol>
  
  <p>When I run the program, shutter glasses start working, but I only see the two images side-by-side on the screen. Could someone help out and tell me what am I doing wrong? I believe that solving this problem might also help others as there does not yet seem to be a simple example how to do this with C#. </p>
  
  <p>Below are the tactical parts of my code. Complete project can be downloaded here: <a href="http://koti.mbnet.fi/jjantti2/NVStereoTest.rar">http://koti.mbnet.fi/jjantti2/NVStereoTest.rar</a></p>
  
  <pre><code>    public void InitializeDevice()
      {
          PresentParameters presentParams = new PresentParameters();
  
          presentParams.Windowed = false;
          presentParams.BackBufferFormat = Format.A8R8G8B8;
          presentParams.BackBufferWidth = _size.Width;
          presentParams.BackBufferHeight = _size.Height;
          presentParams.BackBufferCount = 1;
          presentParams.SwapEffect = SwapEffect.Discard;
          presentParams.PresentationInterval = PresentInterval.One;
          _device = new Device(0, DeviceType.Hardware, this, CreateFlags.SoftwareVertexProcessing, presentParams);
      }
  
      public void LoadSurfaces()
      {
          _imageBuf = _device.CreateOffscreenPlainSurface(_size.Width * 2, _size.Height + 1, Format.A8R8G8B8, Pool.Default);
  
          _imageLeft = Surface.FromBitmap(_device, (Bitmap)Bitmap.FromFile("Blue.png"), Pool.Default);
          _imageRight = Surface.FromBitmap(_device, (Bitmap)Bitmap.FromFile("Red.png"), Pool.Default);
      }
  
      private void Set3D()
      {
          Rectangle destRect = new Rectangle(0, 0, _size.Width, _size.Height);
          _device.StretchRectangle(_imageLeft, _size, _imageBuf, destRect, TextureFilter.None);
          destRect.X = _size.Width;
          _device.StretchRectangle(_imageRight, _size, _imageBuf, destRect, TextureFilter.None);
  
          GraphicsStream gStream = _imageBuf.LockRectangle(LockFlags.None);
  
          byte[] data = new byte[] {0x44, 0x33, 0x56, 0x4e,   //NVSTEREO_IMAGE_SIGNATURE         = 0x4433564e
                                    0x00, 0x00, 0x0F, 0x00,   //Screen width * 2 = 1920*2 = 3840 = 0x00000F00;
                                    0x00, 0x00, 0x04, 0x38,   //Screen height = 1080             = 0x00000438;
                                    0x00, 0x00, 0x00, 0x20,   //dwBPP = 32                       = 0x00000020;
                                    0x00, 0x00, 0x00, 0x02};  //dwFlags = SIH_SCALE_TO_FIT       = 0x00000002;
  
          gStream.Seek(_size.Width * 2 * _size.Height * 4, System.IO.SeekOrigin.Begin);   //last row
          gStream.Write(data, 0, data.Length);
  
          gStream.Close();
  
          _imageBuf.UnlockRectangle();
      }
  
      protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
      {
          _device.BeginScene();
  
          // Get the Backbuffer then Stretch the Surface on it.
          _backBuf = _device.GetBackBuffer(0, 0, BackBufferType.Mono);
          _device.StretchRectangle(_imageBuf, new Rectangle(0, 0, _size.Width * 2, _size.Height + 1), _backBuf, new Rectangle(0, 0, _size.Width, _size.Height), TextureFilter.None);
          _backBuf.ReleaseGraphics();
  
          _device.EndScene();
  
          _device.Present();
  
          this.Invalidate();
      }
  </code></pre>