OSX offscreen without mesa

OSX Cocoa, possible solution for when hardware offscreen not supported:

[NSOpenGLContext setOffScreen:width:height:rowbytes:]

The call requires that we provide our own pixel buffer:

//----------------------------------------------------------------------------
// Seed example, but we need to modify a
//  bit more controlflow vtkCocoaRenderWindow
//----------------------------------------------------------------------------
void vtkCocoaRenderWindow::CreateGLContext()
{
    NSOpenGLContext* context = [[[NSOpenGLContext alloc]
                              initWithFormat:pixelFormat
                              shareContext:nil] autorelease];
  
  
     [context setOffScreen:pixbuff_ptr 
                  width:pixbuff_width
                  height:pixbuff_height
                  rowbytes:pixbuff_rowstride];
...
}

Another source? http://www.cocoabuilder.com/archive/cocoa/136537-creating-an-offscreen-nsview.html