SWIFT++ Relation to Other Packages 
SWIFT++ can be compared to various other packages in terms of functionality provided. Packages that we consider are those that are publicly available. A word about the spectrum of polyhedral proximity query algorithms is in order. On one end is a set of algorithms that take advantage of convex models to speed up proximity queries. These algorithms give a lot of useful proximity information but are restricted to convex models. At the other end of the spectrum are algorithms that can deal with arbitrary collections of triangles. These algorithms can deal with any type of polyhedral collection but are more restricted in the queries that they can answer. SWIFT++ can deal with general polyhedral models while giving substantial proximity query information.
Convex Based Packages

Convex packages rely on objects being convex or composed of convex pieces. There are two main classes of algorithms that are used for convex polyhedral proximity query. One is the Voronoi region based LinCanny (LC) algorithm and its derivatives. Another one is the simplexbased GilbertJohnsonKeerthi (GJK) algorithm and its derivatives. VClip, an LC improvement and modification, was shown to be faster than the enhanced GJK algorithm. SWIFT is shown to be faster than VClip. Until the advent of VClip, GJK was the most robust. Now, SWIFT and VClip are more robust. Taking advantage of multiresolution representations in conjunction with LC, the HWalk system, developed at Stanford, uses VClip as a subroutine along with an inner DobkinKirkpatrick hierarchy (DKH) to "walk" more quickly to the minimum of the distance function. The SWIFT system uses an outer hierarchy of simpler bounding volumes to accelerate the walking. Below is a brief description of each publicly available convex package. More can be learned about them at their respective sites.
Polygon Soup Based Packages

Polygon soup packages operate on lists of triangles. They typically create a hierarchy of bounding volumes whose leaf nodes are the triangles themselves. The hierarchies are composed of spheres, AABB's (AxisAligned Bounding Boxes), OBB's (Oriented Bounding Boxes), SSV's (SphereSwept Volumes), or kDOP's (kDiscrete Oriented Polytopes). These packages are designed to handle rigid motion but some may be adapted to work based upon deformable objects. More can be learned about them at their respective sites.