Returns -1, 0, or +1 according to whether the distance from the point X to
the edge A is less than, equal to, or greater than "r" respectively.
Distances are measured with respect the positions of all points as though
they were projected to lie exactly on the surface of the unit sphere.
REQUIRES: A0 and A1 do not project to antipodal points (e.g., A0 == -A1).
This requires that (A0 != C * A1) for any constant C < 0.
NOTE(ericv): All of the predicates defined here could be extended to handle
edges consisting of antipodal points by implementing additional symbolic
perturbation logic (similar to Sign) in order to rigorously define the
direction of such edges.
Returns -1, 0, or +1 according to whether the distance from the point X to the edge A is less than, equal to, or greater than "r" respectively. Distances are measured with respect the positions of all points as though they were projected to lie exactly on the surface of the unit sphere.
REQUIRES: A0 and A1 do not project to antipodal points (e.g., A0 == -A1). This requires that (A0 != C * A1) for any constant C < 0.
NOTE(ericv): All of the predicates defined here could be extended to handle edges consisting of antipodal points by implementing additional symbolic perturbation logic (similar to Sign) in order to rigorously define the direction of such edges.