Default pattern, with points at 1,1,1 (triangle centres). Add six
intermediate points. These points cause the segment to curve around
the sphere, with the circuits intersecting.
View this model with the command
poly_weave -p 1,1,1::::::FEV geo_2_1 | off_util -M a | off_color -f U -e F -v F | antiview -v 0.02 -e 0.02 -x f
