pub fn helix_rows(
frame: &CoordinateSystem,
helix: &Helix,
) -> GeopResult<Vec<HelixRow>>Expand description
The control rows of a helix around frame.w(), from frame.u(), moving
as helix says along w: 2 n + 1 rows for n equal spans of at most
a quarter turn — a span’s ends at even indices, its middle in between.