ReadOBJ.hpp

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/**
 * MOAB, a Mesh-Oriented datABase, is a software component for creating,
 * storing and accessing finite element mesh data.
 *
 * Copyright 2004 Sandia Corporation.  Under the terms of Contract
 * DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government
 * retains certain rights in this software.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 */

//-----------------------------------------------------------------------------
// Filename : ReadOBJ.hpp
//
// Purpose  : Wavefront obj file reader
//
// Creators : Chelsea D'Angelo, Paul Wilson, Andrew Davis
//
// Date     : 02/16
//
// Owner    : Chelsea D'Angelo
//-----------------------------------------------------------------------------

/**
 * This class will read in an obj file and populate a MOAB instance with the
 * vertex and connectivity information in the file.  A specification for obj files
 * can be found here: https://en.wikipedia.org/wiki/Wavefront_.obj_file
 * This reader only supports a subset of the full file structure, namely,
 * object names, group names, vertices, and faces.
 *
 * Overview of the supported structure:
 *
 * Heading
 * Object line: o object_name
 * Group line: g group_name1
 * Vertex lines: v x y z
 * Face lines (tri): f v1 v2 v3
 * Face lines (quad): f v1 v2 v3 v4
 *
 * Lines that begin w/ anything other than 'o ', 'g ', 'v ', and 'f ' are not
 * supported. If a valid, but unsupported line is found, it will be ignored.
 * If an invalid line is found, an error will be produced.
 * Face lines that contain 'vertex\texture\normal' are handled by ignoring the
 * texture and normal
 *
 *
 * A new meshset will be created for each object or group in the file.
 * Each object and group must have a name, or the line will be ignored.
 * Groups are thought to be collections of elements with no dimension or category and
 * will therefore only be assigned name and id tags.
 * Objects are thought to be closed surfaces.  A surface meshset will be
 * created for each object.  A volume meshset that directly corresponds
 * to the surface meshset will also be created.  These will have name, id,
 * categorty, and dimension tags.  A parent-child relationship exists
 * between the volume and surface meshsets.
 * Vertices will be created and added to a global vertex meshset.
 * Triangular faces will be created and added as members of the surface meshets.
 */

#ifndef READ_OBJ_HPP
#define READ_OBJ_HPP

#ifndef IS_BUILDING_MB
#error "ReadOBJ.hpp isn't supposed to be included into an application"
#endif

#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <map>

#include "moab/Interface.hpp"
#include "moab/ReaderIface.hpp"
#include "FileTokenizer.hpp"
#include "moab/RangeMap.hpp"
#include "MBTagConventions.hpp"

/* struct vertex is a structure that stores coordinates
   of vertices. This is a convenience structure making
   i/o easier.
*/
struct vertex
{
    int vertex_id;
    double coord[3];
};

/* struct face is a structure that stores connectivity.
   This is a convenience structure makin i/o easier.
*/
struct face
{
    int face_id;
    moab::EntityHandle conn[3];
};
namespace moab
{

/* Supported obj file keywords
 */
enum keyword_type
{
    obj_undefined = 0,
    object_start,
    group_start,
    face_start,
    vertex_start,
    valid_unsupported
};

class ReadUtilIface;
class GeomTopoTool;

class ReadOBJ : public ReaderIface
{

  public:
    //! factory method
    static ReaderIface* factory( Interface* );

    ErrorCode load_file( const char* file_name,
                         const EntityHandle* file_set,
                         const FileOptions& opts,
                         const SubsetList* subset_list = 0,
                         const Tag* file_id_tag        = 0 );

    ErrorCode read_tag_values( const char* file_name,
                               const char* tag_name,
                               const FileOptions& opts,
                               std::vector< int >& tag_values_out,
                               const SubsetList* subset_list = 0 );

    //! Constructor
    ReadOBJ( Interface* impl = NULL );

    //! Destructor
    virtual ~ReadOBJ();

  private:
    ReadUtilIface* readMeshIface;

    //! interface instance
    Interface* MBI;

    GeomTopoTool* myGeomTool;

    Tag geom_tag, id_tag, name_tag, category_tag, faceting_tol_tag, geometry_resabs_tag, obj_name_tag;

    /*  The keyword type function matches the first character extracted from each line to a type of
     * line
     */
    keyword_type get_keyword( std::vector< std::string > tokens );

    /*  The match function searches a list of map keys for a match with the token
     */
    template < typename T >
    std::string match( const std::string& token, std::map< std::string, T >& tokenList );

    /* The tokenize function takes a string as input and splits it into
     * a vector of strings based on the delimiter
     */
    static const char* delimiters;

    void tokenize( const std::string& str, std::vector< std::string >& tokens, const char* delimiters );

    /*
     * The create_object funtion will create a new meshset for
     * each object that contains all vertices and faces
     */
    ErrorCode create_new_object( std::string object_name, int object_id, EntityHandle& curr_obj_meshset );

    ErrorCode create_new_group( std::string object_name, int curr_object, EntityHandle& object_meshset );

    /* create_new_vertex converts tokenized string input to
       vertex structure
     */
    ErrorCode create_new_vertex( std::vector< std::string > v_tokens, EntityHandle& vertex_eh );

    /* create_new_face converts tokenized string input to
     * face structure
     */
    ErrorCode create_new_face( std::vector< std::string > f_tokens,
                               const std::vector< EntityHandle >& vertex_list,
                               EntityHandle& face_eh );

    /*
     * The split_quad function creates 1 new vertex and 4 new tri faces
     * from a quad face.
     */

    ErrorCode split_quad( std::vector< std::string > f_tokens,
                          std::vector< EntityHandle >& vertex_list,
                          Range& face_eh );

    ErrorCode create_tri_faces( std::vector< EntityHandle > quad_vert_eh,
                                //                     EntityHandle center_vertex_eh,
                                Range& face_eh );
};

}  // namespace moab

#endif