cells.h

// Copyright (C) 2019 Jorgen S. Dokken
//
// This file is part of DOLFINx (https://www.fenicsproject.org)
//
// SPDX-License-Identifier:    LGPL-3.0-or-later
 
#pragma once
 
#include <cstdint>
#include <dolfinx/mesh/cell_types.h>
#include <vector>
#include <xtensor/xtensor.hpp>
 
namespace dolfinx::io::cells
{
/*
  The basix ordering is used for the geometry nodes, and is shown below
  for a range of cell types.
 
    Triangle:               Triangle6:          Triangle10:
    v
    ^
    |
    2                       2                    2
    |`\                     |`\                  | \
    |  `\                   |  `\                6   4
    |    `\                 4    `3              |     \
    |      `\               |      `\            5   9   3
    |        `\             |        `\          |         \
    0----------1 --> u      0-----5----1         0---7---8---1
 
    Quadrilateral:         Quadrilateral9:         Quadrilateral16:
    v
    ^
    |
    2-----------3          2-----7-----3           2--10--11---3
    |           |          |           |           |           |
    |           |          |           |           7  14  15   9
    |           |          5     8     6           |           |
    |           |          |           |           6  12  13   8
    |           |          |           |           |           |
    0-----------1 --> u    0-----4-----1           0---4---5---1
 
    Tetrahedron:                    Tetrahedron10:               Tetrahedron20
                v
               /
              2                            2                         2
            ,/|`\                        ,/|`\                     ,/|`\
          ,/  |  `\                    ,/  |  `\                 13  |  `9
         ,/    '.   `\                ,8    '.   `6           ,/     4   `\
       ,/       |     `\            ,/       4     `\       12    19 |     `8
     ,/         |       `\        ,/         |       `\   ,/         |       `\
    0-----------'.--------1 -> u 0--------9--'.--------1 0-----14----'.--15----1
     `\.         |      ,/        `\.         |      ,/   `\.  17     |  16 ,/
        `\.      |    ,/             `\.      |    ,5       10.   18 5    ,6
           `\.   '. ,/                  `7.   '. ,/            `\.   '.  7
              `\. |/                       `\. |/                 11. |/
                 `3                            `3                    `3
                    `\.
                       w
 
    Hexahedron:          Hexahedron27:
            w
        6----------7               6----19----7
       /|   ^   v /|              /|         /|
      / |   |  / / |            17 |  25    18|
     /  |   | / /  |            / 14    24 /  15
    4----------5   |           4----16----5   |
    |   |   +--|---|--> u      |22 |  26  | 23|
    |   2------+---3           |   2----13+---3
    |  /       |  /           10  / 21   12  /
    | /        | /             | 9    20  | 11
    |/         |/              |/         |/
    0----------1               0-----8----1
 
*/
 
std::vector<std::uint8_t> perm_vtk(mesh::CellType type, int num_nodes);
 
std::vector<std::uint8_t> perm_gmsh(mesh::CellType type, int num_nodes);
 
std::vector<std::uint8_t> transpose(const std::vector<std::uint8_t>& map);
 
xt::xtensor<std::int64_t, 2>
compute_permutation(const xt::xtensor<std::int64_t, 2>& cells,
                    const std::vector<std::uint8_t>& p);
 
std::int8_t get_vtk_cell_type(mesh::CellType cell, int dim);
 
} // namespace dolfinx::io::cells