pub fn bet2_icosa(n: usize) -> (Vec<[f64; 3]>, Vec<[usize; 3]>)Expand description
FSL-BET2’s make_mesh_from_icosa(n, m) (Bostrix/FSL-BET2 d5acd7f, meshclass/mesh.cpp):
its icosahedron (vertex coordinates tau = 0.8506508084, one = 0.5257311121, in its
orientation and order), every triangle’s last two vertices swapped, then n − 1 passes of
Mesh::retessellate (each triangle (v0, v1, v2) split at its edge midpoints p0 = (v1+v2)/2,
p1 = (v0+v2)/2, p2 = (v0+v1)/2 into (p2, p0, p1), (p1, v0, p2), (p0, v2, p1),
(p2, v1, p0), a midpoint shared with an earlier triangle reused) with every point scaled
back onto the unit sphere by 1/norm after each pass. n = 5 (bet2’s) gives 2562 vertices.