fn armillary() -> impl Iterator<Item = Line>Expand description
The armillary rings, as the segments the stroke source draws.
Each ring circles the largest body around its own tilted axis: the axis is
the ring’s normal, and the frame it is drawn in is the pair of directions
glam reports orthogonal to it. Two different tilts make the rings cross
twice, and circling a body puts each ring in front of it on one half and
behind it on the other — the picture a wash needs, of depth acting on a
stroke that covers nothing.