COM Interface behind the scenes.

[JSoftware]

This page is quite good at explaining it: http://en.wikipedia.org/wiki/Compone...hnical_details

You are right, that you get a pointer to a virtual function table. It's basically a large list of functions that come in the order they are defined in the type definition

To call AddRef on a COM interface in eax do something like this:

   push eax // Reference to self
   mov eax, [eax] // Get the function list
   call [eax+4] // Second function (AddRef)

To call Begin_QueryInterface(SomeGuid) in AsyncIUnknown(inheriting directly from IUnknown, which has 3 functions):

   push SomeGuid // Reference to GUID
   push eax // Reference to self
   mov eax, [eax] // Get the function list
   call [eax+3*4] // First function in AsyncIUnknown (AddRef)

GUIDs aren't really used with DirectX as far as I know, since you create all interfaces through the device

More reading: http://www.polberger.se/components/r...oundation.html