std::vector<std::vector<int16_t>> model3d_impl::get_edges() const
{
    const size_t n = faces_->n();

    std::vector<std::vector<int16_t>> edges_vector(n);
    for (auto& vector : edges_vector)
    {
        vector.resize(n);
    }

    for (size_t i = 0; i < n; i++)
    {
        edges_vector[ (*faces_)[i][0] ][ (*faces_)[i][1] ] = 1;
        edges_vector[ (*faces_)[i][1] ][ (*faces_)[i][0] ] = 1;
        edges_vector[ (*faces_)[i][1] ][ (*faces_)[i][2] ] = 1;
        edges_vector[ (*faces_)[i][2] ][ (*faces_)[i][1] ] = 1;
        edges_vector[ (*faces_)[i][2] ][ (*faces_)[i][0] ] = 1;
        edges_vector[ (*faces_)[i][0] ][ (*faces_)[i][2] ] = 1;
    }

    return edges_vector;

}