cl_Mesh_GmshReader.hpp

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/*
 * BELFEM -- The Berkeley Lab Finite Element Framework
 * Copyright (c) 2026, The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory (subject to receipt of any required
 * approvals from the U.S. Dept. of Energy).  All rights reserved.
 *
 * Developers: Christian Messe, Gregory Giard
 *
 * See the top-level LICENSE file for the complete license and disclaimer.
 */
 
#ifndef BELFEM_CL_MESH_GMSHREADER_HPP
#define BELFEM_CL_MESH_GMSHREADER_HPP
 
#include "typedefs.hpp"
#include "cl_Ascii.hpp"
#include "cl_Cell.hpp"
#include "cl_Node.hpp"
#include "cl_Element.hpp"
#include "cl_Facet.hpp"
#include "cl_Map.hpp"
#include "cl_Block.hpp"
#include "cl_SideSet.hpp"
#include "cl_Mesh.hpp"
 
namespace belfem
{
    namespace mesh
    {
        /*struct GmshPhysicalGroup
        {
            string mLabel = "untitled";
            uint mID = 0;
            uint mDimension = 0;
        };*/
 
//------------------------------------------------------------------------------
 
        class GmshReader : public Ascii
        {
            string mFilename;
 
            // scale factor to convert spatial unit of mesh into m
            const real mMeshScale = 1.0 ;
 
            real   mVersion = 0.0;
 
            uint   mNumberOfNodes = 0;
            uint   mNumberOfElements = 0;
            uint   mNumberOfPhysicalGroups = 0;
 
            // tags in the file
            size_t mNodesTag = 0;
            size_t mElementsTag = 0;
            size_t mPhysicalTag = 0;
 
            // Pointer to mesh object
            Mesh * mMesh;
 
            // dimensions
            uint   mNumberOfDimensions = 0;
 
            // cell containing Nodes
            Cell< Node * > mNodes;
 
            // cell containing Elements
            Cell< Element * > mElements;
 
            // map managing Nodes by ID
            Map< id_t, Node* > mNodeMap;
 
            // MSH 4.1: first physical tag of each entity, per dimension,
            // keyed by the entity ( geometry ) tag. Filled from $Entities
            Map< id_t, uint > mPhysicalTagOfEntity[ 4 ];
 
            // number of elements per dimension
            Vector< index_t > mNumberOfElementsPerDimension;
 
            Cell< Element * > mVertices;
            Cell< Element * > mEdges;
            Cell< Element * > mFaces;
            Cell< Element * > mVolumes;
 
            // groups ids
            Vector< uint > mNodeGroupIDs;
            Vector< uint > mEdgeGroupIDs;
            Vector< uint > mFaceGroupIDs;
            Vector< uint > mVolumeGroupIDs;

            bool mOwnMesh = false;
 
//------------------------------------------------------------------------------
        public:
//------------------------------------------------------------------------------
 
            GmshReader( const string & aPath, Mesh * aMesh = nullptr, const bool aComputeConnectivities=true, const real aMeshScale = 1.0 );
 
//------------------------------------------------------------------------------
 
            ~GmshReader() override;
 
//------------------------------------------------------------------------------
 
            Mesh *
            mesh()
            {
 
                mOwnMesh = false;
 
                return mMesh;
            }
 
//------------------------------------------------------------------------------
        private:
//------------------------------------------------------------------------------
 
            void
            tidy_up_buffer();
 
//------------------------------------------------------------------------------
 
            void
            check_tag_existence();
 
//------------------------------------------------------------------------------
 
            void
            read_version();
 
//------------------------------------------------------------------------------
 
            void
            read_tags_v22();
 
//------------------------------------------------------------------------------
 
            void
            read_nodes_tag_v22( size_t & aCount );
 
//------------------------------------------------------------------------------
 
            void
            read_elements_tag_v22( size_t & aCount );
 
//------------------------------------------------------------------------------
 
            void
            read_physical_tag( size_t & aCount );
 
//------------------------------------------------------------------------------
 
            void
            read_nodes_v22();
 
//------------------------------------------------------------------------------
 
            void
            read_elements_v22();
 
//------------------------------------------------------------------------------
 
            void
            read_mesh_v41();
 
//------------------------------------------------------------------------------
 
            void
            read_entity_tag_v41( size_t & aCount );
 
//------------------------------------------------------------------------------
 
            void
            read_nodes_v41( size_t & aCount );
 
//------------------------------------------------------------------------------
 
            void
            read_elements_v41( size_t & aCount );
 
//------------------------------------------------------------------------------
 
            void
            convert_orders_for_quadratic_volume_elements_to_exo();
 
//------------------------------------------------------------------------------
 
            void
            create_node_map();
 
//------------------------------------------------------------------------------

            void
            read_mesh_dimension();
 
//------------------------------------------------------------------------------
 
            void
            create_element_containers_per_dimension();
 
//------------------------------------------------------------------------------
 
            void
            create_group_ids();
 
//------------------------------------------------------------------------------
 
            void
            create_blocks();
 
//------------------------------------------------------------------------------
 
            void
            create_sidesets();
 
//------------------------------------------------------------------------------
 
            void
            delete_unused_nodes_and_elements();
 
//------------------------------------------------------------------------------
 
            void
            create_mesh();
 
//------------------------------------------------------------------------------
 
            void
            create_vertices();
 
//------------------------------------------------------------------------------
        };
    }
}
#endif //BELFEM_CL_MESH_GMSHREADER_HPP