public TemporaryContext(INativeWindow 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 = native.WindowInfo as WinWindowInfo;
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)
{
success = TryMakeCurrent(window, Context.Handle);
}
else
{
Debug.Print("[WGL] CreateContext failed with error: {0}", Marshal.GetLastWin32Error());
}
if (!success)
{
Debug.WriteLine("[WGL] Failed to create temporary context");
}
}
public TemporaryContext(INativeWindow 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 = native.WindowInfo as WinWindowInfo;
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());
}
}