SharpGL works, and I'm learning about how to call unmanaged C++ from managed C#. It's all about loading libraries and those windows-specific tags. First there's a class, Imports, whose job is specifying and importing all the dll's, and establishing the structure of a few important types, such as PixelFormat. With that accomplished, a class called SharpGL.SceneGraph.OpenGL imports most of the OpenGL functions, and then wraps them with a public interface.

This line, from SharpGL...

public class OpenGL : Imports {
....
[DllImport(LIBRARY_OPENGL)] protected static extern void glVertex3f (float x, float y, float z);
...
}

...means that I can do this, in C#:

 
OpenGL.glVertex3f(x, y, z);

...but that's a protected function, so what I really need to do to call this code from another package is

myOpenGL.Vertex(x, y, z);

This is good, this is progress, but I don't want to write a molecule renderer in straight OpenGL. SharpGL provides a .NET component with a scene graph and lighting controls and camera controls and built-in shape classes, which is very helpful... but I want to use G3D, not SharpGL. G3D exists, and I know it, and I know its maintainers, and I know it is fast, and I know it works. Corey Taylor (one of the maintainers) says he'll try to help, but he's under a crazy workload... so I'm going to keep trying to do this myself.

My current approach:

1. 
   Keep my current C# class, MolecularModel, as the data structure for describing molecules. Unmanaged C++ can access managed, public C# classes.
   


2. 
   Write a small, unmanaged C++ class which renders a MolecularModel to an offscreen bitmap using G3D. Tag just the public interface of this class as dllexports.
   


3. 
   Write a small managed C# class which wraps my unmanaged C++ molecule renderer, by dll-importing the public interface which I exported in step 2. This managed class will not be a control; it's just a wrapper class. This wrapper's fundamental functionality will be to render a MolecularModel into a Bitmap.
   


4. Replace the internals of the current ChemPad molecule viewer control, which is a .NET component, with calls to the managed molecule renderer wrapper. On Paint events, draw the Bitmap created by G3D onto this control's Graphics. Now instead of jmol-net generating the 3D image, G3D will be generating the 3D image.

This approach is different from my previous attempts in that it adds a layer which exposes a small API from unmanaged C++ to managed code. The compiler options will still be fairly hellish, and this isn't as good as really making all of G3D accessible from C#... but it keeps a very clean boundary between the chemistry part of the application and the rendering part of the application. Yikes. Wish me luck.