The region di cells along u and dj cells along v from this one, wrapping
onto the adjacent cube face where the step leaves this one.
The classic cube-sphere bug farm is the six-by-four table of edge rotations
that says which of a neighbor's axes runs which way, and the eight points
where three faces meet is where it is always wrong. There is no table here.
The step is taken in the source face's extended coordinates, turned into a
direction — which is the same direction whichever face claims it — and asked
which region contains it. The rotation is a consequence of directionToFace
picking the dominant axis, so it cannot disagree with the sampling in
regionDirection or with regionForDirection in the streamer.
At a cube corner three faces meet and there are seven neighbors, not eight: the diagonal step off the corner names one of the three faces rather than a missing fourth, and which one is a consequence of the dominant-axis tie-break. That is a real answer to a question with no answer, and callers that walk a ring have to tolerate a repeat rather than assume eight distinct cells.
- regionRegionAddress
- Undocumented
- dinumber
- Undocumented
- djnumber
- Undocumented