Function BuildAnsysMesh

comp/read_ansys.cpp:599–1053

---------------------------------------------------------------------- build a netgen mesh from the parsed model Out parameters carry the bookkeeping needed to build Region objects: vol_regions[name] : 0-based VOL region numbers carrying that elset bnd_regions[name] : 0-based BND region numbers carrying that elset mat_cells[matname] : 0-based VOL region numbers using that material id2vertex[ans

  //    id2vertex[ansysid] : 0-based ngsolve vertex number (-1 if absent)
  // ----------------------------------------------------------------------
  static shared_ptr<netgen::Mesh>
  BuildAnsysMesh (const AnsysModel & m, double scale,
                  map<string,vector<int>> & vol_regions,
                  map<string,vector<int>> & bnd_regions,
                  map<string,vector<int>> & bbnd_regions,
                  map<string,vector<int>> & mat_cells,
                  map<string,vector<int>> & element_sets,
                  vector<int> & id2vertex)
  {
    using namespace netgen;

    const int meshdim = m.maxdim;
    if (meshdim != 2 && meshdim != 3)
      throw Exception("ReadAnsysInp: need a 2D or 3D mesh "
                      "(found max element dimension " + ToString(meshdim) + ")");

    auto mesh = make_shared<Mesh>();
    mesh->SetDimension(meshdim);

    // ---- points + ANSYS-id -> netgen point remap ----
    vector<int> id2pi(m.max_node_id+1, -1);
    id2vertex.assign(m.max_node_id+1, -1);
    for (size_t i = 0; i < m.node_id.size(); i++)
      {
        const auto & c = m.node_xyz[i];
        PointIndex pi = mesh->AddPoint(Point3d(scale*c[0], scale*c[1], scale*c[2]));
        id2pi[m.node_id[i]]     = (int)pi;
        id2vertex[m.node_id[i]] = (int)pi - PointIndex::BASE;   // 0-based vertex nr
      }

    // ---- reverse membership: element id -> set names containing it ----
    std::unordered_map<int, vector<string>> elem2sets;     // all elsets
    std::unordered_map<int, vector<string>> elem2bodies;   // only *ELEMENT (body) elsets
    for (auto & [name, ids] : m.elsets)
      {
        bool body = m.body_elsets.count(name) > 0;
        for (int id : ids)
          {
            elem2sets[id].push_back(name);
            if (body) elem2bodies[id].push_back(name);
          }
      }

    // element id -> material (from any *SECTION, resolving its elset)
    std::unordered_map<int, string> elem_material;
    for (auto & [es, mat] : m.sections)
      {
        if (mat.empty()) continue;
        auto it = m.elsets.find(es);
        if (it == m.elsets.end()) continue;
        for (int id : it->second) elem_material.emplace(id, mat);
      }
    auto MaterialOf = [&](int elemid) -> string
    {
      auto it = elem_material.find(elemid);
      return (it != elem_material.end()) ? it->second : "";
    };