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We present Cgal implementations of two algorithms for computing straight skeletons in the plane, based on exact arithmetic. One code, named Surfer2, can handle multiplicatively weighted planar straight-line graphs (PSLGs) while our second code, Monos, is specifically targeted at monotone polygons. Both codes are available on GitHub. We discuss algorithmic as well as implementational and engineering details of both codes. Furthermore, we present the results of an extensive performance evaluation in which we compared Surfer2 and Monos to the straight-skeleton package included in Cgal. It is not surprising that our special-purpose code Monos outperforms Cgal’s straight-skeleton implementation. But our tests provide ample evidence that also Surfer2 can be expected to be faster and to consume significantly less memory than the Cgal code. And, of course, Surfer2 is more versatile because it can handle multiplicative weights and general PSLGs as input. Thus, Surfer2 currently is the fastest and most general straight-skeleton code available.

We present two software packages for computing straight skeletons: Monos, our implementation of an algorithm by Biedl et al. (2015), computes the straight skeleton of a monotone input polygon, and Surfer2 implements a generalization of an algorithm by Aichholzer and Aurenhammer (1998) to handle multiplicatively-weighted planar straight-line graphs as input. The graphical user interfaces that ship with our codes support step-by-step computations, where each event can be investigated and studied by the user. This makes them a canonical candidate for educational purposes and detailed event analyses. Both codes are freely available on GitHub.