Drawing without GameWindow or GLControl

Edit: I just realized this is already covered in the documentation: http://www.opentk.com/doc/graphics/graphicscontext. Leaving the code here for posterity.

You just need to inform OpenTK that an external context exists:

using OpenTK.Graphics;
 
// Make sure the context  is current and call:
IGraphicsContext context = GraphicsContext.CreateDummyContext();

Then store the IGraphicsContext somewhere so it isn't collected by the GC. This is a "dummy" context, which means it is not actually functional (i.e. calling IGraphicsContext.MakeCurrent(...) will do nothing). The real context belongs to the host application.

In some specific cases, you might wish to control the context through C#, too. In that case, you can create a fully functional context with:

using OpenTK.Graphics;
using OpenTK.Platform;
 
IntPtr windowHandle, contextHandle;
// Retrieve the handles from the host application, then:
IWindowInfo winfo = Utilities.CreateWindowsWindowInfo(windowHandle); // Similar methods exist for X11 and Carbon
IGraphicsContext context = new GraphicsContext(contextHandle, winfo);

You can now use any IGraphicsContext method, for example context.VSync = true. While this can be useful, it is also dangerous: it is your job to ensure the context remains valid (i.e. don't call MakeCurrent(null, null) or Dispose() while the host is using OpenGL!)

Unless you need to direct control through C#, I'd suggest following the first approach.

Edit 2: fixed the second code snipped to pass winfo correctly.

Am I right to assume that the C# plugin is running in the same process as the host? (OpenGL contexts cannot function across processes.)

Assuming the above is true, creating a new context like you do should allow you to use GL methods right away. Can you please post the complete error message?

CreateDummyContext() will try to retrieve the current context using wglGetCurrentContext (or the relevant glx/agl methods). Apparently, this is failing for some reason. Again, the complete error message could give a clue about the cause.

Two other suggestions:

• int handleVal is not valid for 64bit applications. Something to keep in mind if 64bit support is a concern.
• The debug version of OpenTK.dll outputs a lot of debug information during startup (add a trace listener or simply look at the output window in Visual Studio (Ctrl+W, O) to read that information). Attaching that log would also help understand the issue.

GL.LoadAll() is deprecated because entry points are actually loaded by the context, not the GL class. The non-deprecated method is called _context.LoadAll() (in SVN) or (_context as IGraphicsContextInternal).LoadAll() (in 1.0 beta-3).

Now, the strange thing is that entry points are loaded automatically when you create a new context (GraphicsContext.cs, line 177), so you shouldn't have to do that manually. Will have to investigate what is going on here.

In any case, glad it's working.