Compute the orientation of a collection of 2D points [on hold]

To give some background first: I'm porting a Javascript library [1] to C++. I've already ported several of it's dependencies, though the robust-orientation library is particularly nasty to port to C++ and I'm looking for alternatives.

Can you suggest me a library which computes the orientation of a collection of 2D points?

[1] http://ift.tt/1Tc8pNR

[2] http://ift.tt/2vMAypH