pub fn chunk_dirs(corners: [Vector3; 3], tile_res: u32) -> Vec<Vector3>Expand description
The texel-centre world directions of a chunk, row-major, tile_res² of them.
The same mapping the shaders use: barycentric texel centres over the chunk
triangle, folded across the diagonal (u + v > 1) so the whole square holds
valid data, then gnomonically projected onto the unit sphere by normalizing.
Pure — safe to call from a worker thread.