public TemporaryContext(IntPtr native) { Debug.WriteLine("[WGL] Creating temporary context to load extensions"); if (native == null) { throw new ArgumentNullException(); } // Create temporary context and load WGL entry points // First, set a compatible pixel format to the device context // of the temp window WinWindowInfo window = new WinWindowInfo { Handle = native }; WinGraphicsMode selector = new WinGraphicsMode(window.DeviceContext); WinGLContext.SetGraphicsModePFD(selector, GraphicsMode.Default, window); bool success = false; // Then, construct a temporary context and load all wgl extensions Context = new ContextHandle(Wgl.CreateContext(window.DeviceContext)); if (Context != ContextHandle.Zero) { // Make the context current. // Note: on some video cards and on some virtual machines, wglMakeCurrent // may fail with an errorcode of 6 (INVALID_HANDLE). The suggested workaround // is to call wglMakeCurrent in a loop until it succeeds. // See https://www.opengl.org/discussion_boards/showthread.php/171058-nVidia-wglMakeCurrent()-multiple-threads // Sigh... for (int retry = 0; retry < 5 && !success; retry++) { success = Wgl.MakeCurrent(window.DeviceContext, Context.Handle); if (!success) { Debug.Print("wglMakeCurrent failed with error: {0}. Retrying", Marshal.GetLastWin32Error()); System.Threading.Thread.Sleep(10); } } } else { Debug.Print("[WGL] CreateContext failed with error: {0}", Marshal.GetLastWin32Error()); } if (!success) { Debug.WriteLine("[WGL] Failed to create temporary context"); } }
public WinGLContext(GraphicsMode format, WinWindowInfo window, IGraphicsContext sharedContext, int major, int minor, GraphicsContextFlags flags) { // There are many ways this code can break when accessed by multiple threads. The biggest offender is // the sharedContext stuff, which will only become valid *after* this constructor returns. // The easiest solution is to serialize all context construction - hence the big lock, below. lock (LoadLock) { if (window == null) { throw new ArgumentNullException("window", "Must point to a valid window."); } if (window.Handle == IntPtr.Zero) { throw new ArgumentException("window", "Must be a valid window."); } IntPtr current_context = Wgl.GetCurrentContext(); INativeWindow temp_window = null; TemporaryContext temp_context = null; try { if (current_context == IntPtr.Zero) { // Create temporary context to load WGL extensions temp_window = new NativeWindow(); temp_context = new TemporaryContext(temp_window); current_context = Wgl.GetCurrentContext(); if (current_context != IntPtr.Zero && current_context == temp_context.Context.Handle) { new Wgl().LoadEntryPoints(); } } Debug.Print("OpenGL will be bound to window:{0} on thread:{1}", window.Handle, System.Threading.Thread.CurrentThread.ManagedThreadId); ModeSelector = new WinGraphicsMode(window.DeviceContext); Mode = SetGraphicsModePFD(ModeSelector, format, (WinWindowInfo)window); if (Wgl.SupportsFunction("wglCreateContextAttribsARB")) { try { Debug.Write("Using WGL_ARB_create_context... "); List <int> attributes = new List <int>(); attributes.Add((int)ArbCreateContext.MajorVersion); attributes.Add(major); attributes.Add((int)ArbCreateContext.MinorVersion); attributes.Add(minor); if (flags != 0) { attributes.Add((int)ArbCreateContext.ContextFlags); attributes.Add((int)GetARBContextFlags(flags)); attributes.Add((int)ArbCreateContext.ProfileMask); attributes.Add((int)GetARBContextProfile(flags)); } // According to the docs, " <attribList> specifies a list of attributes for the context. // The list consists of a sequence of <name,value> pairs terminated by the // value 0. [...]" // Is this a single 0, or a <0, 0> pair? (Defensive coding: add two zeroes just in case). attributes.Add(0); attributes.Add(0); Handle = new ContextHandle( Wgl.Arb.CreateContextAttribs( window.DeviceContext, sharedContext != null ? (sharedContext as IGraphicsContextInternal).Context.Handle : IntPtr.Zero, attributes.ToArray())); if (Handle == ContextHandle.Zero) { Debug.Print("failed. (Error: {0})", Marshal.GetLastWin32Error()); } } catch (Exception e) { Debug.Print(e.ToString()); } } if (Handle == ContextHandle.Zero) { // Failed to create GL3-level context, fall back to GL2. Debug.Write("Falling back to GL2... "); Handle = new ContextHandle(Wgl.CreateContext(window.DeviceContext)); if (Handle == ContextHandle.Zero) { Handle = new ContextHandle(Wgl.CreateContext(window.DeviceContext)); } if (Handle == ContextHandle.Zero) { throw new GraphicsContextException( String.Format("Context creation failed. Wgl.CreateContext() error: {0}.", Marshal.GetLastWin32Error())); } } Debug.WriteLine(String.Format("success! (id: {0})", Handle)); } finally { if (temp_context != null) { temp_context.Dispose(); temp_context = null; } if (temp_window != null) { temp_window.Dispose(); temp_window = null; } } } // Todo: is this comment still true? // On intel drivers, wgl entry points appear to change // when creating multiple contexts. As a workaround, // we reload Wgl entry points every time we create a // new context - this solves the issue without any apparent // side-effects (i.e. the old contexts can still be handled // using the new entry points.) // Sigh... MakeCurrent(window); new Wgl().LoadEntryPoints(); if (sharedContext != null) { Marshal.GetLastWin32Error(); Debug.Write(String.Format("Sharing state with context {0}: ", sharedContext)); bool result = Wgl.ShareLists((sharedContext as IGraphicsContextInternal).Context.Handle, Handle.Handle); Debug.WriteLine(result ? "success!" : "failed with win32 error " + Marshal.GetLastWin32Error()); } }