Here is an updated video demonstrating the 2D Delaunay triangulation approach to spatialisation for arbitrary speaker layouts.
I have continued development and now consider it done. The new addition over the last week is to track the convex hull. If source position moves outside the convex hull (the area covered by loudspeakers) only the two speakers at the nearest edge are used, and volume will roll off with increasing distance.
I’ll wrap this up as a package, so that it can be shared.