Line data    Source code

       1             : // The libMesh Finite Element Library.
       2             : // Copyright (C) 2002-2023 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
       3             : 
       4             : // This library is free software; you can redistribute it and/or
       5             : // modify it under the terms of the GNU Lesser General Public
       6             : // License as published by the Free Software Foundation; either
       7             : // version 2.1 of the License, or (at your option) any later version.
       8             : 
       9             : // This library is distributed in the hope that it will be useful,
      10             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12             : // Lesser General Public License for more details.
      13             : 
      14             : // You should have received a copy of the GNU Lesser General Public
      15             : // License along with this library; if not, write to the Free Software
      16             : // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      17             : 
      18             : 
      19             : #ifndef LIBMESH_MESH_TET_INTERFACE_H
      20             : #define LIBMESH_MESH_TET_INTERFACE_H
      21             : 
      22             : #include "libmesh/libmesh_config.h"
      23             : 
      24             : // Local includes
      25             : #include "libmesh/bounding_box.h"
      26             : #include "libmesh/enum_elem_type.h"
      27             : #include "libmesh/point.h" // used for specifying holes
      28             : 
      29             : // C++ includes
      30             : #include <cstddef>
      31             : #include <map>
      32             : #include <memory>
      33             : #include <string>
      34             : #include <vector>
      35             : 
      36             : namespace libMesh
      37             : {
      38             : // Forward Declarations
      39             : class UnstructuredMesh;
      40             : class Elem;
      41             : 
      42             : /**
      43             :  * Class \p MeshTetInterface provides an abstract interface for
      44             :  * tetrahedralization of meshes by subclasses.
      45             :  *
      46             :  * \author Roy H. Stogner
      47             :  * \date 2024
      48             :  */
      49          52 : class MeshTetInterface
      50             : {
      51             : public:
      52             : 
      53             :   /**
      54             :    * Constructor. Takes a reference to the mesh.
      55             :    */
      56             :   explicit
      57             :   MeshTetInterface (UnstructuredMesh & mesh);
      58             : 
      59             :   /**
      60             :    * Default destructor in base class.
      61             :    */
      62             :   virtual ~MeshTetInterface();
      63             : 
      64             :   /**
      65             :    * Sets and/or gets the desired tetrahedron volume.  Set to zero to
      66             :    * disable volume constraint.
      67             :    */
      68           0 :   Real & desired_volume() {return _desired_volume;}
      69             : 
      70             :   /**
      71             :    * Sets/gets flag which tells whether to do two steps of Laplace
      72             :    * mesh smoothing after generating the grid.  False by default (for
      73             :    * compatibility with old TetGenMeshInterface behavior).
      74             :    */
      75             :   bool & smooth_after_generating() {return _smooth_after_generating;}
      76             : 
      77             :   /**
      78             :    * Sets and/or gets the desired element type.  This should be a Tet
      79             :    * type.
      80             :    */
      81             :   ElemType & elem_type() {return _elem_type;}
      82             : 
      83             :   /**
      84             :    * Attaches a vector of Mesh pointers defining holes which will be
      85             :    * meshed around.  We use unique_ptr here because we expect that we
      86             :    * may need to modify these meshes internally.
      87             :    */
      88             :   void attach_hole_list(std::unique_ptr<std::vector<std::unique_ptr<UnstructuredMesh>>> holes);
      89             : 
      90             :   /**
      91             :    * This is the main public interface for this function.
      92             :    */
      93             :   virtual void triangulate () = 0;
      94             : 
      95             : protected:
      96             : 
      97             :   /**
      98             :    * Remove volume elements from the given mesh, after converting
      99             :    * their outer boundary faces to surface elements.
     100             :    *
     101             :    * Returns the bounding box of the mesh; this is useful for
     102             :    * detecting misplaced holes later.
     103             :    */
     104             :   static BoundingBox volume_to_surface_mesh (UnstructuredMesh & mesh);
     105             : 
     106             :   /**
     107             :    * This function checks the integrity of the current set of
     108             :    * elements in the Mesh to see if they comprise a hull,
     109             :    * that is:
     110             :    * - If they are all TRI3 elements
     111             :    * - They all have non-nullptr neighbors
     112             :    *
     113             :    * \returns
     114             :    * - 0 if the mesh forms a valid hull
     115             :    * - 1 if a non-TRI3 element is found
     116             :    * - 2 if an element with a nullptr-neighbor is found
     117             :    */
     118             :   unsigned check_hull_integrity();
     119             : 
     120             :   /**
     121             :    * This function prints an informative message and
     122             :    * crashes based on the output of the check_hull_integrity()
     123             :    * function.  It is a separate function so that you
     124             :    * can check hull integrity without crashing if you desire.
     125             :    */
     126             :   void process_hull_integrity_result(unsigned result);
     127             : 
     128             :   /**
     129             :    * Delete original convex hull elements from the Mesh
     130             :    * after performing a Delaunay tetrahedralization.
     131             :    */
     132             :   void delete_2D_hull_elements();
     133             : 
     134             :   /**
     135             :    * The desired volume for the elements in the resulting mesh.
     136             :    * Unlimited (indicated by 0) by default
     137             :    */
     138             :   Real _desired_volume;
     139             : 
     140             :   /**
     141             :    * Flag which tells whether we should smooth the mesh after
     142             :    * it is generated.  False by default.
     143             :    */
     144             :   bool _smooth_after_generating;
     145             : 
     146             :   /**
     147             :    * The exact type of tetrahedra we intend to construct
     148             :    */
     149             :   ElemType _elem_type;
     150             : 
     151             :   /**
     152             :    * Local reference to the mesh we are working with.
     153             :    */
     154             :   UnstructuredMesh & _mesh;
     155             : 
     156             :   /**
     157             :    * A pointer to a vector of meshes each defining a hole.  If this is
     158             :    * nullptr, there are no holes!
     159             :    */
     160             :   std::unique_ptr<std::vector<std::unique_ptr<UnstructuredMesh>>> _holes;
     161             : };
     162             : 
     163             : } // namespace libMesh
     164             : 
     165             : #endif // LIBMESH_MESH_TET_INTERFACE_H