Question

I’m trying to use opengl in C#. I have following code which fails with error 2000 ERROR_INVALID_PIXEL_FORMAT
First definitions:

[DllImport('user32.dll', CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)] public static extern IntPtr GetDC(IntPtr hWnd);  [StructLayout(LayoutKind.Sequential)]     public struct PIXELFORMATDESCRIPTOR     {         public void Init()         {             nSize = (ushort) Marshal.SizeOf(typeof (PIXELFORMATDESCRIPTOR));             nVersion = 1;             dwFlags = PFD_FLAGS.PFD_DRAW_TO_WINDOW | PFD_FLAGS.PFD_SUPPORT_OPENGL | PFD_FLAGS.PFD_DOUBLEBUFFER | PFD_FLAGS.PFD_SUPPORT_COMPOSITION;             iPixelType = PFD_PIXEL_TYPE.PFD_TYPE_RGBA;             cColorBits = 24;             cRedBits = cRedShift = cGreenBits = cGreenShift = cBlueBits = cBlueShift = 0;             cAlphaBits = cAlphaShift = 0;             cAccumBits = cAccumRedBits = cAccumGreenBits = cAccumBlueBits = cAccumAlphaBits = 0;             cDepthBits = 32;             cStencilBits = cAuxBuffers = 0;             iLayerType = PFD_LAYER_TYPES.PFD_MAIN_PLANE;             bReserved = 0;             dwLayerMask = dwVisibleMask = dwDamageMask = 0;         }         ushort nSize;         ushort nVersion;         PFD_FLAGS dwFlags;         PFD_PIXEL_TYPE iPixelType;         byte cColorBits;         byte cRedBits;         byte cRedShift;         byte cGreenBits;         byte cGreenShift;         byte cBlueBits;         byte cBlueShift;         byte cAlphaBits;         byte cAlphaShift;         byte cAccumBits;         byte cAccumRedBits;         byte cAccumGreenBits;         byte cAccumBlueBits;         byte cAccumAlphaBits;         byte cDepthBits;         byte cStencilBits;         byte cAuxBuffers;         PFD_LAYER_TYPES iLayerType;         byte bReserved;         uint dwLayerMask;         uint dwVisibleMask;         uint dwDamageMask;     }      [Flags]     public enum PFD_FLAGS : uint      {         PFD_DOUBLEBUFFER = 0x00000001,         PFD_STEREO = 0x00000002,         PFD_DRAW_TO_WINDOW = 0x00000004,         PFD_DRAW_TO_BITMAP = 0x00000008,         PFD_SUPPORT_GDI = 0x00000010,         PFD_SUPPORT_OPENGL = 0x00000020,         PFD_GENERIC_FORMAT = 0x00000040,         PFD_NEED_PALETTE = 0x00000080,         PFD_NEED_SYSTEM_PALETTE = 0x00000100,         PFD_SWAP_EXCHANGE = 0x00000200,         PFD_SWAP_COPY = 0x00000400,         PFD_SWAP_LAYER_BUFFERS = 0x00000800,         PFD_GENERIC_ACCELERATED = 0x00001000,         PFD_SUPPORT_DIRECTDRAW = 0x00002000,         PFD_DIRECT3D_ACCELERATED = 0x00004000,         PFD_SUPPORT_COMPOSITION = 0x00008000,         PFD_DEPTH_DONTCARE = 0x20000000,         PFD_DOUBLEBUFFER_DONTCARE = 0x40000000,         PFD_STEREO_DONTCARE = 0x80000000     }      public enum PFD_LAYER_TYPES : byte     {         PFD_MAIN_PLANE = 0,         PFD_OVERLAY_PLANE = 1,         PFD_UNDERLAY_PLANE = 255     }      public enum PFD_PIXEL_TYPE : byte     {         PFD_TYPE_RGBA = 0,         PFD_TYPE_COLORINDEX = 1     }      [DllImport('gdi32.dll', CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]     public static extern int ChoosePixelFormat(IntPtr hdc, [In] ref PIXELFORMATDESCRIPTOR ppfd);      [DllImport('gdi32.dll', CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]     public static extern bool SetPixelFormat(IntPtr hdc, int iPixelFormat, ref PIXELFORMATDESCRIPTOR ppfd); [DllImport('opengl32.dll', CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]     public static extern IntPtr wglCreateContext(IntPtr hDC); 

And now the code that fails:

IntPtr dc = Win.GetDC(hwnd);  var pixelformatdescriptor = new GL.PIXELFORMATDESCRIPTOR(); pixelformatdescriptor.Init();  var pixelFormat = GL.ChoosePixelFormat(dc, ref pixelformatdescriptor); if(!GL.SetPixelFormat(dc, pixelFormat, ref pixelformatdescriptor))     throw new Win32Exception(Marshal.GetLastWin32Error()); IntPtr hglrc; if((hglrc = GL.wglCreateContext(dc)) == IntPtr.Zero)     throw new Win32Exception(Marshal.GetLastWin32Error()); //<----- here I have exception 

the same code in managed C++ is working

HDC dc = GetDC(hWnd);  PIXELFORMATDESCRIPTOR pf; pf.nSize = sizeof(PIXELFORMATDESCRIPTOR); pf.nVersion = 1; pf.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER | PFD_SUPPORT_COMPOSITION; pf.cColorBits = 24; pf.cRedBits = pf.cRedShift = pf.cGreenBits = pf.cGreenShift = pf.cBlueBits = pf.cBlueShift = 0; pf.cAlphaBits = pf.cAlphaShift = 0; pf.cAccumBits = pf.cAccumRedBits = pf.cAccumGreenBits = pf.cAccumBlueBits = pf.cAccumAlphaBits = 0; pf.cDepthBits = 32; pf.cStencilBits = pf.cAuxBuffers = 0; pf.iLayerType = PFD_MAIN_PLANE; pf.bReserved = 0; pf.dwLayerMask = pf.dwVisibleMask = pf.dwDamageMask = 0;  int ipf = ChoosePixelFormat(dc, &pf); SetPixelFormat(dc, ipf, &pf);  HGLRC hglrc = wglCreateContext(dc); 

I’ve tried it on VIsta 64-bit with ATI graphic card and on Windows XP 32-bit with Nvidia with the same result in both cases.
Also I want to mention that I don’t want to use any already written framework for it.

Can anyone show me where is the bug in C# code that is causing the exception?

Answer 1

Found solution.
Problem is very strange ugly and really hard to find. Somwhere on the internet I found that when you are linking opengl32.lib while compiling c++ application it must be placed before gdi32.lib. The reason for this is that (supposedly) opengl32.dll is overwriting ChoosePixelFormat and SetPixelFormat functions (and probably more :-). As I found in my c++ version, accidentally it was the case.
Heh, but how to do it in C#
After few days of searching I found that in tao framework they solved it using kernel32.dll LoadLibrary() function and loading opengl32.dll before calling SetPixelFormat

public static bool SetPixelFormat(IntPtr deviceContext, int pixelFormat, ref PIXELFORMATDESCRIPTOR pixelFormatDescriptor) {         Kernel.LoadLibrary('opengl32.dll');         return _SetPixelFormat(deviceContext, pixelFormat, ref pixelFormatDescriptor);     } 

So we know that opengl32.dll must be loaded before gdi32.dll, is there any other way of doing this. After while I thought that we can call some NOP function from opengl32.dll to load it. For example:

[DllImport('opengl32.dll', EntryPoint = 'glGetString', CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)] static extern IntPtr _glGetString(StringName name); public static string glGetString(StringName name) {     return Marshal.PtrToStringAnsi(_glGetString(name)); } public enum StringName : uint {     GL_VENDOR = 0x1F00,     GL_RENDERER = 0x1F01,     GL_VERSION = 0x1F02,     GL_EXTENSIONS = 0x1F03 } 

and on the start of application, before any call to gdi32.dll I use this:

GL.glGetString(0); 

Both ways solves the problem.