This predicate returns true if and only if
the interior of t has non-empty intersection
with the interior of the following infinite box:
the only finite corner of the infinite box is p
and this infinite box is a 90 degree wedge defined
by the intersection of the halfplanes
with supporting lines lhor and lver through p, where
the halfplanes are both on the positive or negative
sides of the supporting lines. The positive or negative
side depends on the relative position of p with respect to s
