ReadSTL.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.
 *
 */

#ifndef READ_STL_HPP
#define READ_STL_HPP

#include <cstdio>
#include "moab/Forward.hpp"
#include "moab/ReaderIface.hpp"

namespace moab
{

class ReadUtilIface;

/**
 * \brief ASCII and Binary Stereo Lithography File readers.
 * \author Jason Kraftcheck
 *
 * STL files contain no connectivity infomration.  Each triangle
 * is specified as by three sets of single-precision coordinate
 * triples.  This reader does not use ANY tolerance when comparing
 * vertex locations to recover connectivity.  The points must be
 * EXACTLY equal (including the sign on zero values.)  If the file
 * was written by an application which represented connectivity
 * explicitly, there is no reason for the vertex coordinates to
 * be anything other than exactly equal.
 *
 * For binary STL files, the defacto standard is that they be written
 * with a little-endian byte order.  The reader will attempt to
 * determine the byte order automatically, and if it is ambiguous,
 * will default to little-endian.  The byte ordering may be forced by
 * by creating an integer tag named "__STL_BYTE_ORDER" and setting a
 * global/mesh value for the tag as 1 for big-endian or 0 for
 * little-endian.
 *
 * For binary files, this reader relies on the file size to determine
 * the validity of the file and may use it in guessing the byte order.
 * This should not be an issue, as the file size can be determined
 * exactly from the number of triangles for a valid file.  However, if
 * for some reason the file is readable even though it is invalid (e.g.
 * it is some hybrid file with STL data in the beginning and some app-
 * specific data appended to the end of the file) the check on the file
 * size can be disabled by giving the reader a something other than a
 * regular file to read from.  For example, on Unix-like systems, have
 * the reader read from a FIFO instead of a file:
 *   mkfifo /tmp/fifo.stlb
 *   cat my_binary_file.stlb > /tmp/fifo.stlb
 * and instruct the MOAB-based application to read from /tmp/fifo.stlb
 */
class ReadSTL : public ReaderIface
{

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

    //! Generic file loading code for both binary and ASCII readers.
    //! Calls reader-specific read_triangles function to do actual I/O.
    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
    ReadSTL( Interface* impl = NULL );

    //! Destructor
    virtual ~ReadSTL();

    // An object to hold vertex coordinates, and an operator
    // for storing them in a STL tree-based container.
    struct Point
    {
        float coords[3];
        bool operator<( const Point& ) const;
    };
    // Data returned by read_triangles.
    struct Triangle
    {
        Point points[3];
    };

    enum ByteOrder
    {
        STL_BIG_ENDIAN,
        STL_LITTLE_ENDIAN,
        STL_UNKNOWN_BYTE_ORDER
    };

  protected:
    // I/O specific part of reader - read ASCII file
    ErrorCode ascii_read_triangles( const char* file_name, std::vector< Triangle >& tris_out );

    // I/O specific part of reader - read binary file
    ErrorCode binary_read_triangles( const char* file_name, ByteOrder byte_order, std::vector< Triangle >& tris_out );

    ReadUtilIface* readMeshIface;

    //! interface instance
    Interface* mdbImpl;
};

}  // namespace moab

#endif