In classic Windows GDI there was a feature called 'Regions'. Basically you could combine simple geometric shapes to construct complex shapes via this feature. A region had a handle and could be called into a dc for filling or used as a clipping region.
Does DirectDraw have an equivalent feature and if so please provide a link to doorway resources. I am just looking for a way in to the subject at this point.
[No sample code to post as not really appropriate to the question]
Specifically for clipping, DDRAW has a LPDIRECTDRAWCLIPPER interface. Search MSDN for DirectDrawCreateClipper() as a starting point. Once you have the clipper interface, you can either apply a window (via SetHWnd) or a RGNDATA structure (via SetClipList) to define your clipping area.