HoneyCombMeshGenerator.cc

// -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
//-----------------------------------------------------------------------------
// Copyright 2000-2026 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
// See the top-level COPYRIGHT file for details.
// SPDX-License-Identifier: Apache-2.0
//-----------------------------------------------------------------------------
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/* HoneyCombMeshGenerator.cc                                   (C) 2000-2023 */
/*                                                                           */
/* Hexagonal mesh generation service.                                        */
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#include "arcane/std/HoneyCombMeshGenerator.h"
 
#include "arcane/utils/Real2.h"
 
#include "arcane/core/IMeshBuilder.h"
#include "arcane/core/IPrimaryMesh.h"
#include "arcane/core/IItemFamily.h"
#include "arcane/core/IParallelMng.h"
#include "arcane/core/MeshBuildInfo.h"
 
#include "arcane/std/HoneyComb2DMeshGenerator_axl.h"
#include "arcane/std/HoneyComb3DMeshGenerator_axl.h"
 
#include <map>
 
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namespace Arcane
{
 
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class SimpleSequentialMeshBuilder
: public TraceAccessor
{
 private:
 
  class Real3Compare
  {
   public:
 
    bool operator()(const Real3& a, const Real3& b) const
    {
      if (!math::isNearlyEqualWithEpsilon(a.x, b.x, m_epsilon))
        return a.x < b.x;
      if (!math::isNearlyEqualWithEpsilon(a.y, b.y, m_epsilon))
        return a.y < b.y;
      if (!math::isNearlyEqualWithEpsilon(a.z, b.z, m_epsilon))
        return a.z < b.z;
      return false;
    }
 
   private:
 
    Real m_epsilon = 1e-14;
  };
 
 public:
 
  explicit SimpleSequentialMeshBuilder(IMesh* pm)
  : TraceAccessor(pm->traceMng())
  , m_mesh(pm)
  {
  }
 
 public:

  Int32 addNode(Real3 coord)
  {
    auto p = m_nodes_coord_map.find(coord);
    if (p != m_nodes_coord_map.end())
      return p->second;
    Int32 v = m_nodes_coordinates.size();
    m_nodes_coordinates.add(coord);
    m_nodes_coord_map.insert(std::make_pair(coord, v));
    return v;
  }
 
  Int32 addCell(Int32 type, ConstArrayView<Real3> nodes_coords)
  {
    m_cells_infos.add(type);
    const Int32 v = m_nb_cell;
    m_cells_infos.add(v);
    ++m_nb_cell;
    for (Real3 coord : nodes_coords)
      m_cells_infos.add(addNode(coord));
    return v;
  }
  ConstArrayView<Int64> cellsInfos() const { return m_cells_infos; }
  Int32 nbCell() const { return m_nb_cell; }
 
  void setNodesCoordinates() const
  {
    Int32 nb_node = m_nodes_coordinates.size();
    UniqueArray<Int64> unique_ids(nb_node);
    for (Integer i = 0; i < nb_node; ++i)
      unique_ids[i] = i;
    UniqueArray<Int32> local_ids(nb_node);
    IItemFamily* node_family = m_mesh->nodeFamily();
    node_family->itemsUniqueIdToLocalId(local_ids, unique_ids);
 
    VariableNodeReal3& mesh_nodes_coordinates(m_mesh->nodesCoordinates());
    NodeInfoListView nodes(node_family);
 
    for (Integer i = 0; i < nb_node; ++i) {
      Node node{ nodes[local_ids[i]] };
      mesh_nodes_coordinates[node] = m_nodes_coordinates[i];
    }
  }
 
 private:
 
  using CoordMap = std::map<Real3, Int32, Real3Compare>;
 
  IMesh* m_mesh = nullptr;
  CoordMap m_nodes_coord_map;
  Int32 m_nb_cell = 0;
  UniqueArray<Int64> m_cells_infos;
  UniqueArray<Real3> m_nodes_coordinates;
};
 
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namespace
{
  void
  _buildCellNodesCoordinates(Real pitch, Real x, Real y, Real z, ArrayView<Real3> coords)
  {
    Real p = 0.5 * pitch;
    Real q = 0.5 * pitch / (math::sqrt(3.0));
    coords[0] = { x - q, y - p, z };
    coords[1] = { x + q, y - p, z };
    coords[2] = { x + 2 * q, y, z };
    coords[3] = { x + q, y + p, z };
    coords[4] = { x - q, y + p, z };
    coords[5] = { x - 2 * q, y, z };
  }
 
} // namespace
 
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class HoneyComb2DMeshGenerator::CellLineInfo
{
 public:
 
  CellLineInfo(Real2 first_center, Int32 nb_cell)
  : m_first_center(first_center)
  , m_nb_cell(nb_cell)
  {}
 
 public:
 
  Real2 m_first_center;
  Int32 m_nb_cell;
};
 
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HoneyComb2DMeshGenerator::
HoneyComb2DMeshGenerator(IPrimaryMesh* mesh)
: TraceAccessor(mesh->traceMng())
, m_mesh(mesh)
{
}
 
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void HoneyComb2DMeshGenerator::
_buildCells()
{
  // In parallel, only rank 0 builds the mesh
  IParallelMng* pm = m_mesh->parallelMng();
  if (pm->commRank() == 0)
    _buildCells2();
  else {
    m_mesh->setDimension(2);
    m_mesh->allocateCells(0, Int64ConstArrayView(), true);
  }
}
 
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void HoneyComb2DMeshGenerator::
_buildCells2()
{
  SimpleSequentialMeshBuilder simple_mesh_builder(m_mesh);
 
  const Real pitch = m_pitch;
  const Integer nb_ring = m_nb_ring;
 
  info() << "Build Hexagonal 2D Cells nb_layer=" << nb_ring;
 
  UniqueArray<Real3> cell_nodes_coords(6);
  UniqueArray<CellLineInfo> cells_line_info;
 
  // u1, u2 and u3 are the directional vectors following the
  // directions of the hexagon
  Real2 u1(0.5 * pitch * math::sqrt(3.0), -0.5 * pitch);
  Real2 u2(0.5 * pitch * math::sqrt(3.0), 0.5 * pitch);
  Real2 u3(pitch * 0.0, pitch * 1.0);
 
  // Cells above the center
  for (Integer i = (-nb_ring + 1); i < 1; ++i) {
    Real x0 = u3[0] * i - u1[0] * (nb_ring - 1);
    Real y0 = u3[1] * i - u1[1] * (nb_ring - 1);
    Real2 pos(x0, y0);
    pos += m_origin;
    Integer nb_cell_in_line = 2 * nb_ring - 1 + i;
    cells_line_info.add(CellLineInfo(pos, nb_cell_in_line));
  }
 
  // Cells below the center
  for (Integer i = 1; i < nb_ring; ++i) {
    Real x0{ u2[0] * i - u1[0] * (nb_ring - 1) };
    Real y0{ u2[1] * i - u1[1] * (nb_ring - 1) };
    Real2 pos(x0, y0);
    pos += m_origin;
    Integer nb_cell_in_line = 2 * nb_ring - 1 - i;
    cells_line_info.add(CellLineInfo(pos, nb_cell_in_line));
  }
 
  for (const CellLineInfo& cli : cells_line_info) {
    Real2 xy = cli.m_first_center;
    for (Integer j = 0, n = cli.m_nb_cell; j < n; ++j) {
      _buildCellNodesCoordinates(m_pitch, xy.x, xy.y, 0.0, cell_nodes_coords);
      simple_mesh_builder.addCell(IT_Hexagon6, cell_nodes_coords);
      xy += u1;
    }
  }
 
  m_mesh->setDimension(2);
  m_mesh->allocateCells(simple_mesh_builder.nbCell(), simple_mesh_builder.cellsInfos(), true);
 
  simple_mesh_builder.setNodesCoordinates();
}
 
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void HoneyComb2DMeshGenerator::
generateMesh(Real2 origin, Real pitch, Integer nb_ring)
{
  m_pitch = pitch;
  m_nb_ring = nb_ring;
  m_origin = origin;
  _buildCells();
}
 
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class HoneyComb2DMeshGeneratorService
: public ArcaneHoneyComb2DMeshGeneratorObject
{
 public:
 
  explicit HoneyComb2DMeshGeneratorService(const ServiceBuildInfo& sbi)
  : ArcaneHoneyComb2DMeshGeneratorObject(sbi)
  {}
 
 public:
 
  void fillMeshBuildInfo(MeshBuildInfo& build_info) override
  {
    build_info.addNeedPartitioning(true);
  }
  void allocateMeshItems(IPrimaryMesh* pm) override
  {
    info() << "HoneyComb2DMeshGenerator: allocateMeshItems()";
    HoneyComb2DMeshGenerator g(pm);
    Real pitch = options()->pitchSize();
    Integer nb_layer = options()->nbLayer();
    if (pitch <= 0.0)
      ARCANE_FATAL("Invalid valid value '{0}' for pitch (should be > 0.0)", pitch);
    if (nb_layer <= 0)
      ARCANE_FATAL("Invalid valid value '{0}' for 'nb-layer' (should be > 0)", nb_layer);
    g.generateMesh(options()->origin(), pitch, nb_layer);
  }
 
 private:
};
 
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ARCANE_REGISTER_SERVICE_HONEYCOMB2DMESHGENERATOR(HoneyComb2D, HoneyComb2DMeshGeneratorService);
 
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class HoneyComb3DMeshGenerator::CellLineInfo
{
 public:
 
  CellLineInfo(Real2 first_center, Real bottom, Real top, Int32 nb_cell)
  : m_first_center(first_center)
  , m_bottom(bottom)
  , m_top(top)
  , m_nb_cell(nb_cell)
  {}
 
 public:
 
  Real2 m_first_center;
  Real m_bottom;
  Real m_top;
  Int32 m_nb_cell;
};
 
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HoneyComb3DMeshGenerator::
HoneyComb3DMeshGenerator(IPrimaryMesh* mesh)
: TraceAccessor(mesh->traceMng())
, m_mesh(mesh)
{
}
 
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void HoneyComb3DMeshGenerator::
generateMesh(Real2 origin, Real pitch, Integer nb_ring, ConstArrayView<Real> heights)
{
  m_pitch = pitch;
  m_nb_ring = nb_ring;
  m_origin = origin;
  m_heights = heights;
 
  // Check that we have the correct number of values and that they are increasing
  const Integer nb_height = m_heights.size();
  if (nb_height < 2)
    ARCANE_FATAL("Bad number of heights '{0}' (minimum=2)", nb_height);
  for (Integer i = 0; i < (nb_height - 1); ++i)
    if (m_heights[i] > m_heights[i + 1])
      ARCANE_FATAL("Heights are not increasing ({0} < {1})", m_heights[i], m_heights[i + 1]);
 
  _buildCells();
}
 
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void HoneyComb3DMeshGenerator::
_buildCells()
{
  // In parallel, only rank 0 builds the mesh
  IParallelMng* pm = m_mesh->parallelMng();
  if (pm->commRank() == 0)
    _buildCells2();
  else {
    m_mesh->setDimension(3);
    m_mesh->allocateCells(0, Int64ConstArrayView(), true);
  }
}
 
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void HoneyComb3DMeshGenerator::
_buildCells2()
{
  SimpleSequentialMeshBuilder simple_mesh_builder(m_mesh);
 
  const Real pitch = m_pitch;
  const Integer nb_ring = m_nb_ring;
  const Integer nb_height = m_heights.size();
  if (nb_height < 2)
    ARCANE_FATAL("Bad number of heights '{0}' (minimum=2)", nb_height);
  info() << "Build Hexagonal 3D Cells nb_layer=" << nb_ring << " nb_height=" << nb_height;
 
  UniqueArray<Real3> cell_nodes_coords(12);
  UniqueArray<CellLineInfo> cells_line_info;
 
  // u1, u2 and u3 are the directional vectors following the
  // directions of the hexagon
  Real2 u1(0.5 * pitch * math::sqrt(3.0), -0.5 * pitch);
  Real2 u2(0.5 * pitch * math::sqrt(3.0), 0.5 * pitch);
  Real2 u3(pitch * 0.0, pitch * 1.0);
 
  for (Integer zz = 0; zz < (nb_height - 1); ++zz) {
    // Cells above the center
    for (Integer i = (-nb_ring + 1); i < 1; ++i) {
      Real x0 = u3[0] * i - u1[0] * (nb_ring - 1);
      Real y0 = u3[1] * i - u1[1] * (nb_ring - 1);
      Real2 pos(x0, y0);
      pos += m_origin;
      Integer nb_cell_in_line = 2 * nb_ring - 1 + i;
      cells_line_info.add(CellLineInfo(pos, m_heights[zz], m_heights[zz + 1], nb_cell_in_line));
    }
 
    // Cells below the center
    for (Integer i = 1; i < nb_ring; ++i) {
      Real x0{ u2[0] * i - u1[0] * (nb_ring - 1) };
      Real y0{ u2[1] * i - u1[1] * (nb_ring - 1) };
      Real2 pos(x0, y0);
      pos += m_origin;
      Integer nb_cell_in_line = 2 * nb_ring - 1 - i;
      cells_line_info.add(CellLineInfo(pos, m_heights[zz], m_heights[zz + 1], nb_cell_in_line));
    }
  }
 
  for (const CellLineInfo& cli : cells_line_info) {
    Real2 xy = cli.m_first_center;
    for (Integer j = 0, n = cli.m_nb_cell; j < n; ++j) {
      _buildCellNodesCoordinates(m_pitch, xy.x, xy.y, cli.m_bottom, cell_nodes_coords.subView(0, 6));
      _buildCellNodesCoordinates(m_pitch, xy.x, xy.y, cli.m_top, cell_nodes_coords.subView(6, 6));
      simple_mesh_builder.addCell(IT_Octaedron12, cell_nodes_coords);
      xy += u1;
    }
  }
 
  m_mesh->setDimension(3);
  m_mesh->allocateCells(simple_mesh_builder.nbCell(), simple_mesh_builder.cellsInfos(), true);
 
  simple_mesh_builder.setNodesCoordinates();
}
 
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class HoneyComb3DMeshGeneratorService
: public ArcaneHoneyComb3DMeshGeneratorObject
{
 public:
 
  explicit HoneyComb3DMeshGeneratorService(const ServiceBuildInfo& sbi)
  : ArcaneHoneyComb3DMeshGeneratorObject(sbi)
  {}
 
 public:
 
  void fillMeshBuildInfo(MeshBuildInfo& build_info) override
  {
    build_info.addNeedPartitioning(true);
  }
  void allocateMeshItems(IPrimaryMesh* pm) override
  {
    info() << "HoneyComb2DMeshGenerator: allocateMeshItems()";
    HoneyComb3DMeshGenerator g(pm);
    Real pitch = options()->pitchSize();
    Integer nb_layer = options()->nbLayer();
    ConstArrayView<Real> heights = options()->heights();
    Integer nb_height = heights.size();
    if (pitch <= 0.0)
      ARCANE_FATAL("Invalid valid value '{0}' for pitch (should be > 0.0)", pitch);
    if (nb_layer <= 0)
      ARCANE_FATAL("Invalid valid value '{0}' for 'nb-layer' (should be > 0)", nb_layer);
    if (nb_height <= 2)
      ARCANE_FATAL("Invalid valid value '{0}' for 'nb-height' (should be >= 2)", nb_height);
    g.generateMesh(options()->origin(), pitch, nb_layer, heights);
  }
 
 private:
};
 
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ARCANE_REGISTER_SERVICE_HONEYCOMB3DMESHGENERATOR(HoneyComb3D, HoneyComb3DMeshGeneratorService);
 
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} // End namespace Arcane
 
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