Function fair 

pub fn fair(
    mesh: &mut HalfedgeMesh,
    vertices: &[VertexId],
    options: &FairOptions,
) -> Result<FairReport, FairError>

Fair the given vertices of a mesh in place; every other vertex is fixed.

Duplicates in vertices are ignored. Fixed vertices are bit-identical afterwards. The output is deterministic: it depends on the mesh and the set of vertices, not on their order.

Errors

FairError: a removed vertex, a free group with no fixed neighbour, a non-triangle or degenerate triangle near the region with cotangent weights, a bad tolerance, and a solve that does not converge.