STL.cpp

/*---------------------------------------------------------------------------*\
 *
 *  bitpit
 *
 *  Copyright (C) 2015-2021 OPTIMAD engineering Srl
 *
 *  -------------------------------------------------------------------------
 *  License
 *  This file is part of bitpit.
 *
 *  bitpit is free software: you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License v3 (LGPL)
 *  as published by the Free Software Foundation.
 *
 *  bitpit is distributed in the hope that it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 *  License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with bitpit. If not, see <http://www.gnu.org/licenses/>.
 *
\*---------------------------------------------------------------------------*/
 
#include <cassert>
#include <cstdint>
#include <cstring>
 
#include "bitpit_common.hpp"
#include "bitpit_operators.hpp"
 
#include "STL.hpp"
#include "logger.hpp"
 
namespace bitpit {

 
// Header is 80 characters long
const std::size_t STLBase::BINARY_HEADER_SIZE = 80 * sizeof(STLBase::BINARY_UINT8);
 
// An empty binary file contains the header plus a float_32 stating that there
// are zero trinagles in the file.
const std::size_t STLBase::BINARY_MINIMUM_SIZE = STLBase::BINARY_HEADER_SIZE + sizeof(STLBase::BINARY_UINT32);
 
// Each facet is defined by the following information:
//  - Normal: 3 float_32
//  - Vertices' coordinates: 3x float_32
//  - Attribute byte count: 1 unit_16
const std::size_t STLBase::BINARY_FACET_SIZE = 3 * sizeof(BINARY_REAL32) + 3 * 3 * sizeof(BINARY_REAL32) + sizeof(BINARY_UINT16);
 
const std::string STLBase::ASCII_SOLID_BEGIN  = "solid";
const std::string STLBase::ASCII_SOLID_END    = "endsolid";
const std::string STLBase::ASCII_FACET_BEGIN  = "facet";
const std::string STLBase::ASCII_FACET_END    = "endfacet";
const std::string STLBase::ASCII_FILE_BEGIN   = STLBase::ASCII_SOLID_BEGIN;
const std::string STLBase::ASCII_FILE_END     = STLBase::ASCII_SOLID_END;
const std::size_t STLBase::ASCII_MINIMUM_SIZE = STLBase::ASCII_FILE_BEGIN.length() + STLBase::ASCII_FILE_END.length();

STLBase::STLBase(const std::string &filename)
{
    setFilename(filename);
    setFormat(FormatUnknown);
}

STLBase::STLBase(const std::string &filename, Format format)
{
    setFilename(filename);
    setFormat(format);
}

const std::string & STLBase::getFilename() const
{
    return m_filename;
}

void STLBase::setFilename(const std::string &filename)
{
    m_filename = filename;
}

STLBase::Format STLBase::getFormat() const
{
    return m_format;
}

void STLBase::setFormat(STLBase::Format format)
{
    m_format = format;
}


STLReader::STLReader(const std::string &filename, Format format)
    : STLBase(filename)
{
    if (format == FormatUnknown) {
        format = detectFormat(filename);
    }
 
    if (format == FormatUnknown) {
        throw std::runtime_error("Invalid STL format.");
    }
 
    setFormat(format);
}

STLReader::Format STLReader::detectFormat(const std::string &filename)
{
    std::ifstream fileStream;
 
    // Get the file size
    fileStream.open(filename, std::ifstream::ate | std::ifstream::binary);
    if (!fileStream.good()) {
        fileStream.close();
        throw std::runtime_error("Invalid STL.");
    }
 
    std::size_t fileSize = fileStream.tellg();
    fileStream.close();
    fileStream.clear();
 
    //
    // ASCII check
    //
 
    // Check if the size is compatible with an ASCII STL file.
    //
    // An ASCII contains at least the "solid " and "endsolid" markers, therefore
    // the minimum size of an empty ASCII file is 14 bytes.
    if (fileSize < ASCII_MINIMUM_SIZE) {
        return FormatUnknown;
    }
 
    // If a files starts with "solid" and ends with "endsolid" is an ASCII file.
    //
    // Binary files should never start with "solid ", but that's not mandatory.
    // We need to check both the beginning and the and of the file to be sure
    // of the file format.
    char c;
    std::size_t bufferPos;
 
    bufferPos = 0;
    std::string beginString(ASCII_FILE_BEGIN.size(), ' ');
    fileStream.open(filename, std::ifstream::binary);
    while (fileStream.get(c)) {
        if (bufferPos == 0 && (std::isblank(c) || std::isspace(c))) {
            continue;
        }
 
        beginString.at(bufferPos) = tolower(c);
        ++bufferPos;
        if (bufferPos == ASCII_FILE_BEGIN.size()) {
            break;
        }
    }
    fileStream.close();
    fileStream.clear();
 
    bool maybeASCII = (beginString.compare(ASCII_FILE_BEGIN) == 0);
    if (maybeASCII) {
        // Open the file
        fileStream.open(filename, std::ifstream::ate | std::ifstream::binary);
 
        // Move the cursor at the beginning of the last non-empty line
        bool empty = true;
        fileStream.seekg(-1, std::ios_base::cur);
        while (fileStream.get(c)) {
            if (c == '\n') {
                if (!empty) {
                    break;
                }
            }
 
            if (empty) {
                empty = (!std::isblank(c) && !std::isspace(c));
            }
 
            fileStream.seekg(-2, std::ios_base::cur);
        }
 
        // Search the end-line keyword
        bufferPos = 0;
        std::string endString(ASCII_SOLID_END.size(), ' ');
        while (fileStream.get(c)) {
            if (bufferPos == 0 && (std::isblank(c) || std::isspace(c))) {
                continue;
            }
 
            endString.at(bufferPos) = tolower(c);
            ++bufferPos;
            if (bufferPos == ASCII_SOLID_END.size()) {
                break;
            }
        }
 
        // Close the file
        fileStream.close();
        fileStream.clear();
 
        // Check if the end-solid keyword was found
        bool isASCII = (endString.compare(ASCII_SOLID_END) == 0);
        if (isASCII) {
            return FormatASCII;
        }
    }
 
    //
    // Binary check
    //
 
    // Check if the size is compatible with a binary STL file.
    //
    // An empty binary file contains the header and the number of facets,
    // therefore the minimum size of an empty binary file is 84 bytes.
    if (fileSize < BINARY_MINIMUM_SIZE) {
        return FormatUnknown;
    }
 
    // Read the number of facets
    std::uint32_t nFacets;
 
    fileStream.open(filename, std::ifstream::binary);
    fileStream.seekg(BINARY_HEADER_SIZE);
    fileStream.read(reinterpret_cast<char *>(&nFacets), sizeof(BINARY_UINT32));
    fileStream.close();
    fileStream.clear();
 
    // Check that the size of the file is compatiblewith the number of facets
    std::size_t expectedFileSize = BINARY_HEADER_SIZE + sizeof(BINARY_UINT32) + (nFacets * BINARY_FACET_SIZE);
    if (fileSize == expectedFileSize) {
        return FormatBinary;
    }
 
    return FormatUnknown;
}

int STLReader::inspect(InspectionInfo *info)
{
    // Begin read
    int beginError = readBegin();
    if (beginError != 0) {
        return beginError;
    }
 
    // Get format
    Format format = getFormat();
 
    // Inspect file
    int inspectionError;
    if (format == FormatASCII) {
        inspectionError = inspectASCII(info);
    } else {
        inspectionError = inspectBinary(info);
    }
 
    // End read
    int endError = readEnd();
 
    // Done
    if (inspectionError != 0) {
        return inspectionError;
    } else if (endError != 0) {
        return endError;
    } else {
        return 0;
    }
}

int STLReader::inspectASCII(InspectionInfo *info)
{
    // Initialize info
    info->nSolids = 0;
    info->solidErrors.clear();
    info->solidNames.clear();
    info->solidFacetCount.clear();
    info->solidVertexCount.clear();
 
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Set cursor at file begin
    m_fileHandle.clear();
    std::streamoff start_pos = m_fileHandle.tellg();
    m_fileHandle.seekg(0);
 
    // Scan file
    std::string word;
    std::stringstream sname;
 
    int inspectionError = 0;
    while (m_lineStream.readLine(m_fileHandle) >= 0) {
        // Get keyword
        if ((m_lineStream >> word) && (word.compare(ASCII_SOLID_BEGIN) == 0)) {
            // Initialize inspection info
            int solidIndex = info->nSolids;
 
            ++info->nSolids;
            info->solidErrors.emplace_back();
            info->solidNames.emplace_back("");
            info->solidFacetCount.emplace_back(0);
            info->solidVertexCount.emplace_back(0);
 
            // Get solid name
            sname.str("");
            while (m_lineStream >> word) {
                sname << word << " ";
            }
            info->solidNames[solidIndex] = sname.str();
            utils::string::trim(info->solidNames[solidIndex]);
 
            // Get solid info
            inspectionError = inspectSolidASCII(info->solidFacetCount.data() + solidIndex, info->solidErrors.data() + solidIndex);
            if (inspectionError != 0) {
                break;
            }
 
            info->solidVertexCount[solidIndex] = 3 * info->solidFacetCount[solidIndex];
        }
    }
 
    // Restore cursor position
    m_fileHandle.clear();
    m_fileHandle.seekg(start_pos);
 
    return inspectionError;
}

int STLReader::inspectSolidASCII(std::size_t *nFacets, std::array<bool, 6> *errors)
{
    // Initialize solid information
    (*nFacets) = 0;
    errors->fill(false);
 
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Inspect the solid
    std::string word;
    std::streamoff last_valid_pos;
 
    int inspectError = 0;
    while (true) {
        // Get next line
        last_valid_pos = m_fileHandle.tellg();
        m_lineStream.readLine(m_fileHandle);
        if (!(m_lineStream >> word)) {
            word = "";
        }
 
        // Exit conditions
        if (m_fileHandle.eof()) {
            break;
        } else if (word.compare(ASCII_SOLID_END) == 0) {
            break;
        } else if (word.compare(ASCII_SOLID_BEGIN) == 0) {
            break;
        }
 
        // Look for keyword "facet"
        if (word.compare(ASCII_FACET_BEGIN) == 0) {
            ++(*nFacets);
 
            m_fileHandle.seekg(last_valid_pos);
            inspectError = inspectFacetASCII(errors);
            if (inspectError != 0) {
                break;
            }
        }
    }
 
    // Check block temination
    if (word.compare(ASCII_SOLID_END) != 0) {
        (*errors)[0] = true;
        m_fileHandle.clear();
        m_fileHandle.seekg(last_valid_pos);
    }
 
    return inspectError;
}

int STLReader::inspectFacetASCII(std::array<bool, 6> *errors)
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Check facet data
    std::string word;
    std::streamoff last_valid_pos;
 
    last_valid_pos = m_fileHandle.tellg();
    m_lineStream.readLine(m_fileHandle);
    if ((!(m_lineStream >> word)) || (word.compare(ASCII_FACET_BEGIN) == 0)) {
        word = "begin";
    }
 
    std::size_t nV = 0;
    bool normal_found = false;
    while ((!m_fileHandle.eof())
           && ((word.compare(ASCII_FACET_END) != 0)
           &&  (word.compare(ASCII_FACET_BEGIN)    != 0)
           &&  (word.compare(ASCII_SOLID_END) != 0)
           &&  (word.compare(ASCII_SOLID_BEGIN)    != 0))) {
 
        // Check facet normal or facet vertices
        if (word.compare("begin") == 0) {
            if ((m_lineStream >> word) && (word.compare("normal") == 0)) {
                normal_found = true;
 
                int nxyz = 0;
                while (m_lineStream >> word) {
                    nxyz++;
                }
 
                if (nxyz != 3) {
                    (*errors)[3] = true;
                }
            }
        }
        else if (word.compare("vertex") == 0) {
            nV++;
 
            int nxyz = 0;
            while (m_lineStream >> word) {
                nxyz++;
            }
 
            if (nxyz != 3) {
                (*errors)[5] = true;
            }
        }
 
        // Get next line
        last_valid_pos = m_fileHandle.tellg();
        m_lineStream.readLine(m_fileHandle);
        if (!(m_lineStream >> word)) {
            word = "";
        }
    }
 
    // Check if facket section is properly closed
    if (word.compare(ASCII_FACET_END) != 0) {
        (*errors)[1] = true;
        m_fileHandle.clear(),
        m_fileHandle.seekg(last_valid_pos);
    }
 
    // Check if normal is valid
    if (!normal_found) {
        (*errors)[2] = true;
    }
 
    // Check if number of vertices is valid
    if (nV != 3) {
        (*errors)[4] = true;
    }
 
    return 0;
}

int STLReader::inspectBinary(InspectionInfo *info)
{
    // Initialize info
    info->nSolids = 0;
    info->solidErrors.clear();
    info->solidNames.clear();
    info->solidFacetCount.clear();
    info->solidVertexCount.clear();
 
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Set cursor at file begin
    m_fileHandle.clear();
    std::streamoff start_pos = m_fileHandle.tellg();
    m_fileHandle.seekg(0);
 
    // Inspect header
    for (std::size_t i = 0; i < BINARY_HEADER_SIZE / sizeof(BINARY_UINT8); ++i) {
        BINARY_UINT8 headerCharacter;
        m_fileHandle.read(reinterpret_cast<char*>(&headerCharacter), sizeof(BINARY_UINT8));
    }
 
    if (m_fileHandle.eof()) {
        info->solidErrors[0][0] = true;
        return 0;
    }
 
    // Binary files does not contain information about the solid name
    info->solidNames.push_back("");
 
    // Read number of facets
    BINARY_UINT32 nFacets;
    m_fileHandle.read(reinterpret_cast<char *>(&nFacets), sizeof(BINARY_UINT32));
    info->solidFacetCount.push_back((std::size_t) nFacets);
    info->solidVertexCount.push_back((std::size_t) (3 * nFacets));
 
    if (m_fileHandle.eof()) {
        info->solidErrors[0][0] = true;
        return 0;
    }
 
    // Check facet data
    std::size_t n = 0;
    while ((!m_fileHandle.eof()) && (n < nFacets)) {
        std::array<char, BINARY_FACET_SIZE> facetData;
        m_fileHandle.read(facetData.data(), BINARY_FACET_SIZE);
        n++;
    }
 
    // Check number of facets
    if (n < nFacets) {
        info->solidErrors[0][1] = true;
    }
 
    // Reset cursor position
    m_fileHandle.clear();
    m_fileHandle.seekg(start_pos);
 
    return 0;
}

void STLReader::displayInspectionInfo(const InspectionInfo &info, std::ostream &out) const
{
    out << "Inspection info" << "\n";
 
    out << "  Filename : " << getFilename() << "\n";
 
    Format format = getFormat();
    if (format == FormatBinary) {
        out << "  Format   : binary" << "\n";
    } else {
        out << "  Format   : ASCII" << "\n";
    }
 
    out << "\n";
    if (info.nSolids > 0) {
        out << "  Solid count    : " << info.nSolids << "\n";
 
        for (int i = 0; i < info.nSolids; ++i) {
            out << "\n";
            out << "  Solid index    : " << i << "\n";
            out << "  Solid name     : " << info.solidNames[i] << "\n";
            out << "  Solid facets   : " << info.solidFacetCount[i] << "\n";
            out << "  Solid vertices : " << info.solidVertexCount[i] << "\n";
 
            if (info.solidErrors[i][0]) {
                out << "    **ERROR** Unterminated solid block." << "\n";
            }
            if (info.solidErrors[i][1]) {
                out << "    **ERROR** Unterminated facet block." << "\n";
            }
            if (info.solidErrors[i][2]) {
                out << "    **ERROR** Normal data are missing." << "\n";
            }
            if (info.solidErrors[i][3]) {
                out << "    **ERROR** Wrong number of components for normal data." << "\n";
            }
            if (info.solidErrors[i][4]) {
                out << "    **ERROR** Wrong number of vertices in facet block." << "\n";
            }
            if (info.solidErrors[i][5]) {
                out << "    **ERROR** Wrong number of coordinates for vertice." << "\n";
            }
        }
    } else {
        out << "  STL file contains no solids." << "\n";
    }
 
    out.flush();
}

int STLReader::readBegin()
{
    if (m_fileHandle.is_open()) {
        return -2;
    }
 
    m_fileHandle.open(getFilename(), std::ifstream::in | std::ifstream::binary);
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    return 0;
}

int STLReader::readEnd()
{
    m_fileHandle.close();
 
    return 0;
}

int STLReader::readSolid(std::string *name, std::size_t *nV, std::size_t *nT,
                         std::vector<std::array<double, 3>> *V, std::vector<std::array<double, 3>> *N,
                         std::vector<std::array<std::size_t, 3>> *T)
{
    return readSolid("", name, nV, nT, V, N, T);
}

int STLReader::readSolid(const std::string &solid, std::string *name, std::size_t *nV, std::size_t *nT,
                         std::vector<std::array<double, 3>> *V, std::vector<std::array<double, 3>> *N,
                         std::vector<std::array<std::size_t, 3>> *T)
{
    // Read header
    std::size_t nSolidFacets;
    int headerError = readHeader(solid, name, &nSolidFacets);
    if (headerError != 0) {
        return headerError;
    }
 
    // Read facet data
    V->resize(*nV + 3 * nSolidFacets, {{0., 0., 0.}});
    N->resize(*nT + nSolidFacets, {{0., 0., 0.}});
    T->resize(*nT + nSolidFacets, {{0, 0, 0}});
 
    for (std::size_t i = 0; i < *nT; ++i) {
        // Read facet data
        std::array<double, 3> *V0 = V->data() + *nV + 3 * i;
        std::array<double, 3> *V1 = V0 + 1;
        std::array<double, 3> *V2 = V1 + 1;
 
        int facetError = readFacet(V0, V1, V2, N->data() + i);
        if (facetError != 0) {
            return facetError;
        }
 
        // Update facet->vertex connectivity
        (*T)[i][0] = *nV + 3 * i;
        (*T)[i][1] = (*T)[i][0] + 1;
        (*T)[i][2] = (*T)[i][1] + 1;
    }
 
    // Read footer
    int footerError = readFooter(solid);
    if (footerError != 0) {
        return footerError;
    }
 
    return 0;
}

int STLReader::readHeader(std::string *name, std::size_t *nT)
{
    return readHeader("", name, nT);
}

int STLReader::readHeader(const std::string &solid, std::string *name, std::size_t *nT)
{
    Format format = getFormat();
 
    int error;
    if (format == FormatASCII) {
        error = readHeaderASCII(solid, name, nT);
    } else {
        std::string trimmedSolid = solid;
        utils::string::trim(trimmedSolid);
        if (!trimmedSolid.empty()) {
            log::cout() << "WARNING: loading solids with a specific name is only supported for ASCII files." << std::endl;
            log::cout() << "         The reader will read the next solid." << std::endl;
        }
 
        error = readHeaderBinary(name, nT);
    }
 
    return error;
}

int STLReader::readFooter()
{
    return readFooter("");
}

int STLReader::readFooter(const std::string &solid)
{
    Format format = getFormat();
 
    int error;
    if (format == FormatASCII) {
        error = readFooterASCII(solid);
    } else {
        error = readFooterBinary();
    }
 
    return error;
}

int STLReader::readFacet(std::array<double, 3> *V0, std::array<double, 3> *V1,
                         std::array<double, 3> *V2, std::array<double, 3> *N)
{
    Format format = getFormat();
 
    int error;
    if (format == FormatASCII) {
        error = readFacetASCII(V0, V1, V2, N);
    } else {
        error = readFacetBinary(V0, V1, V2, N);
    }
 
    return error;
}

int STLReader::readHeaderASCII(const std::string &solid, std::string *name, std::size_t *nT)
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Get solid key
    std::string solidKey = solid;
    utils::string::trim(solidKey);
    solidKey = ASCII_SOLID_BEGIN + " " + solidKey;
    utils::string::trim(solidKey);
 
    // Scan file until solid is found
    std::string word;
    std::string line;
 
    std::streamoff start_pos   = m_fileHandle.tellg();
    std::streamoff current_pos = start_pos + 1;
 
    bool solidFound = false;
    bool wrapAround = solidKey.compare(ASCII_SOLID_BEGIN) != 0;
    while (!solidFound && (start_pos != current_pos)) {
        // Get current line
        m_lineStream.readLine(m_fileHandle);
 
        // Check end of file
        if (m_fileHandle.eof()) {
            if (wrapAround) {
                m_fileHandle.clear();
                m_fileHandle.seekg(0);
                wrapAround = false;
            } else {
                solidFound = false;
                break;
            }
        }
        current_pos = m_fileHandle.tellg();
 
        // Look for keyword "solid"
        if ((m_lineStream >> word) && (word.compare(ASCII_SOLID_BEGIN) == 0)) {
            m_lineStream.copyLine(&line);
            if (solidKey.compare(ASCII_SOLID_BEGIN) == 0 || line.compare(solidKey) == 0) {
                *name = line.erase(0, ASCII_SOLID_BEGIN.size());
                *name = utils::string::trim(*name);
 
                start_pos = current_pos;
 
                solidFound = true;
            }
        }
    }
 
    if (!solidFound) {
        return -2;
    }
 
    // Read number of facets
    m_fileHandle.clear();
    m_fileHandle.seekg(start_pos);
 
    std::array<bool, 6> solidErrors;
    inspectSolidASCII(nT, &solidErrors);
 
    m_fileHandle.clear();
    m_fileHandle.seekg(start_pos);
 
    return 0;
}

int STLReader::readFooterASCII(const std::string &solid)
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Get solid key
    std::string solidKey = solid;
    utils::string::trim(solidKey);
    solidKey = ASCII_SOLID_END + " " + solidKey;
    utils::string::trim(solidKey);
 
    // Look for the end of solid section
    std::string word;
    std::string line;
 
    while (true) {
        // Get next line
        m_lineStream.readLine(m_fileHandle);
 
        // Get next word
        if (!(m_lineStream >> word)) {
            word = "";
        }
 
        // Handle the word
        if (word.compare(ASCII_SOLID_END) == 0) {
            m_lineStream.copyLine(&line);
            if (line.compare(solidKey) != 0) {
                log::cout() << "WARNING: end-solid key does not match the solid name." << std::endl;
                log::cout() << "         Expected end-solid key : " << solidKey << std::endl;
                log::cout() << "         Current end-solid key  : " << line << std::endl;
            }
 
            break;
        } else if (word.compare(ASCII_SOLID_BEGIN) == 0) {
            return -2;
        } else if (m_fileHandle.eof()) {
            return -2;
        }
    }
 
    return 0;
}

int STLReader::readFacetASCII(std::array<double, 3> *V0, std::array<double, 3> *V1,
                              std::array<double, 3> *V2, std::array<double, 3> *N)
{
    // Read facet data
    std::string word;
    std::string value;
    std::streamoff last_valid_pos;
 
    int error = 0;
    int nFacetVertices = 0;
    std::string target = "facet";
    while (true) {
        // Get next line
        last_valid_pos = m_fileHandle.tellg();
        m_lineStream.readLine(m_fileHandle);
        if (!(m_lineStream >> word)) {
            continue;
        }
 
        // Handle the word
        //
        // Beginning of faacet section and normal are on the same line, after
        // finding the beginning of the facet section we have to extract the
        // next word without getting a new line.
        if (word.compare(ASCII_FACET_BEGIN) == 0) {
            if (word.compare(target) == 0) {
                target = "normal";
 
                if (!(m_lineStream >> word)) {
                    continue;
                }
            } else {
                error = -2;
                break;
            }
        }
 
        if (word.compare(ASCII_FACET_END) == 0) {
            if (word.compare(target) == 0) {
                break;
            } else {
                error = -2;
                break;
            }
        } else if (word.compare("normal") == 0) {
            if (word.compare(target) == 0) {
                for (int k = 0; k < 3; ++k) {
                    m_lineStream >> value;
                    (*N)[k] = stod(value);
                }
                target = "vertex";
            } else {
                error = -2;
                break;
            }
        } else if (word.compare("vertex") == 0) {
            if (word.compare(target) == 0) {
                std::array<double, 3> *coords;
                if (nFacetVertices == 0) {
                    coords = V0;
                } else if (nFacetVertices == 1) {
                    coords = V1;
                } else if (nFacetVertices == 2) {
                    coords = V2;
                    target = ASCII_FACET_END;
                } else {
                    error = -3;
                    break;
                }
 
                for (int k = 0; k < 3; ++k) {
                    m_lineStream >> value;
                    (*coords)[k] = stod(value);
                }
 
                nFacetVertices++;
            } else {
                error = -2;
                break;
            }
        } else if (word.compare(ASCII_SOLID_BEGIN) == 0) {
            error = -2;
            break;
        } else if (word.compare(ASCII_SOLID_END) == 0) {
            error = -2;
            break;
        } else if (m_fileHandle.eof()) {
            error = -2;
            break;
        }
    }
 
    // Restor cursor position
    if (error != 0) {
        m_fileHandle.clear();
        m_fileHandle.seekg(last_valid_pos);
    }
 
    return error;
}

int STLReader::readHeaderBinary(std::string *name, std::size_t *nT)
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Binary data has not information about solid names
    (*name) = "";
 
    // Skip header
    for (std::size_t i = 0; i < BINARY_HEADER_SIZE / sizeof(BINARY_UINT8); ++i) {
        BINARY_UINT8 headerCharacter;
        m_fileHandle.read(reinterpret_cast<char *>(&headerCharacter), sizeof(BINARY_UINT8));
    }
 
    // Read number of facets
    BINARY_UINT32 nSolidFacets;
    m_fileHandle.read(reinterpret_cast<char *>(&nSolidFacets), sizeof(BINARY_UINT32));
    *nT = nSolidFacets;
 
    // Check if the end of file has been reached
    if (m_fileHandle.eof()) {
        return -2;
    }
 
    return 0;
}

int STLReader::readFooterBinary()
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Nothing to do
    return 0;
}

int STLReader::readFacetBinary(std::array<double, 3> *V0, std::array<double, 3> *V1,
                               std::array<double, 3> *V2, std::array<double, 3> *N)
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Read facet data
    std::array<char, BINARY_FACET_SIZE> facetData;
    m_fileHandle.read(facetData.data(), BINARY_FACET_SIZE);
    int facetDataOffset = 0;
 
    // Store normal
    for (int k = 0; k < 3; ++k) {
        (*N)[k] = (double) *(reinterpret_cast<BINARY_REAL32 *>(facetData.data() + facetDataOffset));
        facetDataOffset += sizeof(BINARY_REAL32);
    }
 
    // Store vertex coordinates
    for (int k = 0; k < 3; ++k) {
        (*V0)[k] = (double) *(reinterpret_cast<BINARY_REAL32 *>(facetData.data() + facetDataOffset));
        facetDataOffset += sizeof(BINARY_REAL32);
    }
 
    for (int k = 0; k < 3; ++k) {
        (*V1)[k] = (double) *(reinterpret_cast<BINARY_REAL32 *>(facetData.data() + facetDataOffset));
        facetDataOffset += sizeof(BINARY_REAL32);
    }
 
    for (int k = 0; k < 3; ++k) {
        (*V2)[k] = (double) *(reinterpret_cast<BINARY_REAL32 *>(facetData.data() + facetDataOffset));
        facetDataOffset += sizeof(BINARY_REAL32);
    }
 
    // Check if the end of file has been reached
    if (m_fileHandle.eof()) {
        return -2;
    }
 
    return 0;
}


STLWriter::STLWriter(const std::string &filename, Format format)
    : STLBase(filename, format)
{
    if (format == FormatUnknown) {
        throw std::runtime_error("Invalid STL format.");
    }
}

int STLWriter::writeBegin(WriteMode writeMode, bool partialWrite)
{
    if (m_fileHandle.is_open()) {
        return -2;
    }
 
    Format format = getFormat();
 
    std::ios_base::openmode openMode;
    if (format == FormatBinary) {
        if (writeMode == WriteOverwrite) {
            openMode = std::ofstream::out | std::ofstream::binary;
        } else if (partialWrite && writeMode == WriteAppend) {
            openMode = std::ofstream::app | std::ofstream::binary;
        } else {
            throw std::runtime_error("Specified write mode is not supported for binary files.");
        }
    } else {
        if (writeMode == WriteOverwrite) {
            openMode = std::ofstream::out;
        } else if (writeMode == WriteAppend) {
            openMode = std::ofstream::app;
        } else {
            throw std::runtime_error("Specified write mode is not supported for ASCII files.");
        }
    }
 
    m_fileHandle.open(getFilename(), openMode);
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Set stream properties
    m_fileHandle << std::scientific;
 
    return 0;
}

int STLWriter::writeEnd()
{
    m_fileHandle.close();
 
    return 0;
}

int STLWriter::writeSolid(const std::string &name, std::size_t nV, std::size_t nT,
                          const std::vector<std::array<double,3>> &V, const std::vector<std::array<double,3>> &N,
                          const std::vector<std::array<std::size_t,3>> &T)
{
    // Check input variables
    if (V.size() < nV) {
        return -2;
    }
 
    if (T.size() < nT) {
        return -2;
    }
 
    if (N.size() < nT) {
        return -2;
    }
 
    // Save stream flags
    std::ios::fmtflags streamFlags(m_fileHandle.flags());
 
    // Write header
    int headerError = writeHeader(name, nT);
    if (headerError != 0) {
        return headerError;
    }
 
    // Write facet data
    for (std::size_t i = 0; i < nT; ++i) {
        // Check connectivity
        for (int k = 0; k < 3; ++k) {
            if (T[i][k] >= nV) {
                return -2;
            }
        }
 
        // Write data
        int facetError = writeFacet(V[T[i][0]], V[T[i][1]], V[T[i][2]], N[i]);
        if (facetError != 0) {
            return facetError;
        }
    }
 
    // Write footer
    int footerError = writeFooter(name);
    if (footerError != 0) {
        return footerError;
    }
 
    // Restore stream flags
    m_fileHandle.flags(streamFlags);
 
    return 0;
}

int STLWriter::writeHeader(const std::string &name, std::size_t nT)
{
    Format format = getFormat();
 
    int error;
    if (format == FormatASCII) {
        error = writeHeaderASCII(name, nT);
    } else {
        error = writeHeaderBinary(name, nT);
    }
 
    return error;
}

int STLWriter::writeFooter(const std::string &name)
{
    Format format = getFormat();
 
    int error;
    if (format == FormatASCII) {
        error = writeFooterASCII(name);
    } else {
        error = writeFooterBinary(name);
    }
 
    return error;
}

int STLWriter::writeFacet(const std::array<double, 3> &V0, const std::array<double, 3> &V1,
                          const std::array<double, 3> &V2, const std::array<double, 3> &N)
{
    Format format = getFormat();
 
    int error;
    if (format == FormatASCII) {
        error = writeFacetASCII(V0, V1, V2, N);
    } else {
        error = writeFacetBinary(V0, V1, V2, N);
    }
 
    return error;
}

int STLWriter::writeHeaderASCII(const std::string &name, std::size_t nT)
{
    BITPIT_UNUSED(nT);
 
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Write header
    std::stringstream sheader;
    sheader << ASCII_SOLID_BEGIN << " " << name;
 
    // Write number of facets
    std::string header = sheader.str();
    header = utils::string::trim(header);
    m_fileHandle << header << "\n";
 
    return 0;
}

int STLWriter::writeFooterASCII(const std::string &name)
{
    BITPIT_UNUSED(name);
 
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Write footer
    std::stringstream sfooter;
    sfooter << ASCII_SOLID_END << " " << name;
 
    std::string footer;
    footer = sfooter.str();
    footer = utils::string::trim(footer);
    m_fileHandle << footer << "\n";
 
    return 0;
}

int STLWriter::writeFacetASCII(const std::array<double, 3> &V0, const std::array<double, 3> &V1,
                               const std::array<double, 3> &V2, const std::array<double, 3> &N)
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Facet header
    m_fileHandle << "  " << ASCII_FACET_BEGIN;
 
    // Facet normal
    m_fileHandle << " normal ";
    m_fileHandle << N[0] << " ";
    m_fileHandle << N[1] << " ";
    m_fileHandle << N[2];
    m_fileHandle << "\n";
 
    // Facet vertices
    m_fileHandle << "    outer loop" << "\n";
 
    m_fileHandle << "      vertex ";
    m_fileHandle << V0[0] << " ";
    m_fileHandle << V0[1] << " ";
    m_fileHandle << V0[2];
    m_fileHandle << "\n";
 
    m_fileHandle << "      vertex ";
    m_fileHandle << V1[0] << " ";
    m_fileHandle << V1[1] << " ";
    m_fileHandle << V1[2];
    m_fileHandle << "\n";
 
    m_fileHandle << "      vertex ";
    m_fileHandle << V2[0] << " ";
    m_fileHandle << V2[1] << " ";
    m_fileHandle << V2[2];
    m_fileHandle << "\n";
 
    m_fileHandle << "    endloop"    << "\n";
 
    // Facet footer
    m_fileHandle << "  " << ASCII_FACET_END << "\n";
 
    return 0;
}

int STLWriter::writeHeaderBinary(const std::string &name, std::size_t nT)
{
    BITPIT_UNUSED(name);
 
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Write header
    for (std::size_t i = 0; i < BINARY_HEADER_SIZE / sizeof(BINARY_UINT8); ++i) {
        BINARY_UINT8 headerCharacter = 0;
        m_fileHandle.write(reinterpret_cast<char*>(&headerCharacter), sizeof(BINARY_UINT8));
    }
 
    // Write number of facets
    BINARY_UINT32 nFacets = (BINARY_UINT32) nT;
    m_fileHandle.write(reinterpret_cast<char *>(&nFacets), sizeof(BINARY_UINT32));
 
    return 0;
}

int STLWriter::writeFooterBinary(const std::string &name)
{
    BITPIT_UNUSED(name);
 
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Nothing to do
    return 0;
}

int STLWriter::writeFacetBinary(const std::array<double, 3> &V0, const std::array<double, 3> &V1,
                                const std::array<double, 3> &V2, const std::array<double, 3> &N)
{
    // Check stream status
    if (!m_fileHandle.good()) {
        return -1;
    }
 
    // Normals
    for (int k = 0; k < 3; ++k) {
        BINARY_REAL32 N_k = (BINARY_REAL32) N[k];
        m_fileHandle.write(reinterpret_cast<char *>(&N_k), sizeof(BINARY_REAL32));
    }
 
    // Vertices
    for (int k = 0; k < 3; ++k) {
        BINARY_REAL32 V_k = (BINARY_REAL32) V0[k];
        m_fileHandle.write(reinterpret_cast<char *>(&V_k), sizeof(BINARY_REAL32));
    }
 
    for (int k = 0; k < 3; ++k) {
        BINARY_REAL32 V_k = (BINARY_REAL32) V1[k];
        m_fileHandle.write(reinterpret_cast<char *>(&V_k), sizeof(BINARY_REAL32));
    }
 
    for (int k = 0; k < 3; ++k) {
        BINARY_REAL32 V_k = (BINARY_REAL32) V2[k];
        m_fileHandle.write(reinterpret_cast<char *>(&V_k), sizeof(BINARY_REAL32));
    }
 
    // Attribute byte count
    //
    // In the standard format, this should be zero because most software
    // does not understand anything else.
    // Attribute byte count
    BINARY_UINT16 attributeByteCount = 0;
    m_fileHandle.write(reinterpret_cast<char *>(&attributeByteCount), sizeof(BINARY_UINT16));
 
    return 0;
}
 
}