Trying to figure out how to use the Voronoi library in 1.54 Boost (Great stuff BTW, Thanks!)

I am using the library to shatter a 2d convex polygon.

So I need to generate polygons that are the results of clipping a voronoi cell against my convex poly.

I am having hard time figuring out how to properly identify the direction of the semi-infinite edge.

I know i can obtain the general direction of the infinite edge from the participating cell points,

but I am not clear on how to distinguish between two possible directions in the semi-finite case.

Any help would be much appreciated!

Thanks!

Nick.