Function segment_mesh_faces 

pub fn segment_mesh_faces(
    positions: &[f64],
    indices: &[u32],
    options: &SegmentOptions,
) -> Result<MeshSegmentation, String>

Segment a triangle mesh into smooth regions and recognize each region’s analytic carrier. positions are xyz triples; indices is a triangle index buffer, or empty to treat positions as a raw soup of consecutive triangles (the binary-STL layout of read_binary_stl).