public override void MakeCurrent(IWindowInfo window)
{
lock (LoadLock)
{
bool success;
WinWindowInfo wnd = window as WinWindowInfo;
if (wnd != null)
{
if (wnd.Handle == IntPtr.Zero)
{
throw new ArgumentException("window", "Must point to a valid window.");
}
success = TryMakeCurrent(wnd, Handle.Handle);
DeviceContext = wnd.DeviceContext;
}
else
{
success = Wgl.MakeCurrent(IntPtr.Zero, IntPtr.Zero);
DeviceContext = IntPtr.Zero;
}
if (!success)
{
throw new GraphicsContextException(String.Format(
"Failed to make context {0} current. Error: {1}", this, Marshal.GetLastWin32Error()));
}
}
}
public void Dispose()
{
if (Context != ContextHandle.Zero)
{
Wgl.MakeCurrent(IntPtr.Zero, IntPtr.Zero);
Wgl.DeleteContext(Context.Handle);
}
}
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");
}
}
/// <summary>
/// Tries to make the context current over several attempts.
/// </summary>
/// <remarks>
/// On some video cards and on some virtual machines, wglMakeCurrent
/// may fail with an error code 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
/// In a majority of cases this will succeed on the first try.
/// </remarks>
/// <returns>Whether the context was successfully made current.</returns>
private static bool TryMakeCurrent(WinWindowInfo window, IntPtr contextHandle)
{
bool success = false;
for (int retry = 0; retry < 10 && !success; retry++)
{
success = Wgl.MakeCurrent(window.DeviceContext, contextHandle);
if (!success)
{
Debug.Print("wglMakeCurrent failed with error: {0}. Retrying", Marshal.GetLastWin32Error());
System.Threading.Thread.Sleep(10);
}
}
return(success);
}