assimp.assimp/code/AssetLib/Obj/ObjFileParser.cpp

/*
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Open Asset Import Library (assimp)
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All rights reserved.

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  copyright notice, this list of conditions and the
  following disclaimer.

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  derived from this software without specific prior
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/
#ifndef ASSIMP_BUILD_NO_OBJ_IMPORTER

#include "ObjFileParser.h"
#include "ObjFileData.h"
#include "ObjFileMtlImporter.h"
#include "ObjTools.h"
#include <assimp/BaseImporter.h>
#include <assimp/DefaultIOSystem.h>
#include <assimp/ParsingUtils.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/Importer.hpp>
#include <cstdlib>
#include <memory>
#include <utility>

namespace Assimp {

constexpr const char ObjFileParser::DEFAULT_MATERIAL[];

ObjFileParser::ObjFileParser() :
        m_DataIt(),
        m_DataItEnd(),
        m_pModel(nullptr),
        m_uiLine(0),
        m_buffer(),
        mEnd(&m_buffer[Buffersize]),
        m_pIO(nullptr),
        m_progress(nullptr),
        m_originalObjFileName() {
    std::fill_n(m_buffer, Buffersize, '\0');
}

ObjFileParser::ObjFileParser(IOStreamBuffer<char> &streamBuffer, const std::string &modelName,
        IOSystem *io, ProgressHandler *progress,
        const std::string &originalObjFileName) :
        m_DataIt(),
        m_DataItEnd(),
        m_pModel(nullptr),
        m_uiLine(0),
        m_buffer(),
        m_pIO(io),
        m_progress(progress),
        m_originalObjFileName(originalObjFileName) {
    std::fill_n(m_buffer, Buffersize, '\0');

    // Create the model instance to store all the data
    m_pModel.reset(new ObjFile::Model());
    m_pModel->mModelName = modelName;

    // create default material and store it
    m_pModel->mDefaultMaterial = new ObjFile::Material;
    m_pModel->mDefaultMaterial->MaterialName.Set(DEFAULT_MATERIAL);
    m_pModel->mMaterialLib.emplace_back(DEFAULT_MATERIAL);
    m_pModel->mMaterialMap[DEFAULT_MATERIAL] = m_pModel->mDefaultMaterial;

    // Start parsing the file
    parseFile(streamBuffer);
}

void ObjFileParser::setBuffer(std::vector<char> &buffer) {
    m_DataIt = buffer.begin();
    m_DataItEnd = buffer.end();
}

ObjFile::Model *ObjFileParser::GetModel() const {
    return m_pModel.get();
}

void ObjFileParser::parseFile(IOStreamBuffer<char> &streamBuffer) {
    // only update every 100KB or it'll be too slow
    //const unsigned int updateProgressEveryBytes = 100 * 1024;
    const unsigned int bytesToProcess = static_cast<unsigned int>(streamBuffer.size());
    const unsigned int progressTotal = bytesToProcess;
    unsigned int processed = 0u;
    size_t lastFilePos = 0u;

    bool insideCstype = false;
    std::vector<char> buffer;
    while (streamBuffer.getNextDataLine(buffer, '\\')) {
        m_DataIt = buffer.begin();
        m_DataItEnd = buffer.end();
        mEnd = &buffer[buffer.size() - 1] + 1;

        // Handle progress reporting
        const size_t filePos(streamBuffer.getFilePos());
        if (lastFilePos < filePos) {
            processed = static_cast<unsigned int>(filePos);
            lastFilePos = filePos;
            m_progress->UpdateFileRead(processed, progressTotal);
        }

        // handle c-stype section end (http://paulbourke.net/dataformats/obj/)
        if (insideCstype) {
            switch (*m_DataIt) {
            case 'e': {
                std::string name;
                getNameNoSpace(m_DataIt, m_DataItEnd, name);
                insideCstype = name != "end";
            } break;
            }
            goto pf_skip_line;
        }

        // parse line
        switch (*m_DataIt) {
        case 'v': // Parse a vertex texture coordinate
        {
            ++m_DataIt;
            if (*m_DataIt == ' ' || *m_DataIt == '\t') {
                size_t numComponents = getNumComponentsInDataDefinition();
                if (numComponents == 3) {
                    // read in vertex definition
                    getVector3(m_pModel->mVertices);
                } else if (numComponents == 4) {
                    // read in vertex definition (homogeneous coords)
                    getHomogeneousVector3(m_pModel->mVertices);
                } else if (numComponents == 6) {
                    // fill previous omitted vertex-colors by default
                    if (m_pModel->mVertexColors.size() < m_pModel->mVertices.size()) {
                        m_pModel->mVertexColors.resize(m_pModel->mVertices.size(), aiVector3D(0, 0, 0));
                    }
                    // read vertex and vertex-color
                    getTwoVectors3(m_pModel->mVertices, m_pModel->mVertexColors);
                }
                // append omitted vertex-colors as default for the end if any vertex-color exists
                if (!m_pModel->mVertexColors.empty() && m_pModel->mVertexColors.size() < m_pModel->mVertices.size()) {
                    m_pModel->mVertexColors.resize(m_pModel->mVertices.size(), aiVector3D(0, 0, 0));
                }
            } else if (*m_DataIt == 't') {
                // read in texture coordinate ( 2D or 3D )
                ++m_DataIt;
                size_t dim = getTexCoordVector(m_pModel->mTextureCoord);
                m_pModel->mTextureCoordDim = std::max(m_pModel->mTextureCoordDim, (unsigned int)dim);
            } else if (*m_DataIt == 'n') {
                // Read in normal vector definition
                ++m_DataIt;
                getVector3(m_pModel->mNormals);
            }
        } break;

        case 'p': // Parse a face, line or point statement
        case 'l':
        case 'f': {
            getFace(*m_DataIt == 'f' ? aiPrimitiveType_POLYGON : (*m_DataIt == 'l' ? aiPrimitiveType_LINE : aiPrimitiveType_POINT));
        } break;

        case '#': // Parse a comment
        {
            getComment();
        } break;

        case 'u': // Parse a material desc. setter
        {
            std::string name;

            getNameNoSpace(m_DataIt, m_DataItEnd, name);

            size_t nextSpace = name.find(' ');
            if (nextSpace != std::string::npos)
                name = name.substr(0, nextSpace);

            if (name == "usemtl") {
                getMaterialDesc();
            }
        } break;

        case 'm': // Parse a material library or merging group ('mg')
        {
            std::string name;

            getNameNoSpace(m_DataIt, m_DataItEnd, name);

            size_t nextSpace = name.find(' ');
            if (nextSpace != std::string::npos)
                name = name.substr(0, nextSpace);

            if (name == "mg")
                getGroupNumberAndResolution();
            else if (name == "mtllib")
                getMaterialLib();
            else
                goto pf_skip_line;
        } break;

        case 'g': // Parse group name
        {
            getGroupName();
        } break;

        case 's': // Parse group number
        {
            getGroupNumber();
        } break;

        case 'o': // Parse object name
        {
            getObjectName();
        } break;

        case 'c': // handle cstype section start
        {
            std::string name;
            getNameNoSpace(m_DataIt, m_DataItEnd, name);
            insideCstype = name == "cstype";
            goto pf_skip_line;
        }

        default: {
        pf_skip_line:
            m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
        } break;
        }
    }
}

void ObjFileParser::copyNextWord(char *pBuffer, size_t length) {
    size_t index = 0;
    m_DataIt = getNextWord<DataArrayIt>(m_DataIt, m_DataItEnd);
    if (*m_DataIt == '\\') {
        ++m_DataIt;
        ++m_DataIt;
        m_DataIt = getNextWord<DataArrayIt>(m_DataIt, m_DataItEnd);
    }
    while (m_DataIt != m_DataItEnd && !IsSpaceOrNewLine(*m_DataIt)) {
        pBuffer[index] = *m_DataIt;
        index++;
        if (index == length - 1) {
            break;
        }
        ++m_DataIt;
    }

    ai_assert(index < length);
    pBuffer[index] = '\0';
}

static bool isDataDefinitionEnd(const char *tmp) {
    if (*tmp == '\\') {
        tmp++;
        if (IsLineEnd(*tmp)) {
            return true;
        }
    }
    return false;
}

static bool isNanOrInf(const char *in) {
    // Look for "nan" or "inf", case insensitive
    return ((in[0] == 'N' || in[0] == 'n') && ASSIMP_strincmp(in, "nan", 3) == 0) ||
           ((in[0] == 'I' || in[0] == 'i') && ASSIMP_strincmp(in, "inf", 3) == 0);
}

size_t ObjFileParser::getNumComponentsInDataDefinition() {
    size_t numComponents(0);
    const char *tmp(&m_DataIt[0]);
    bool end_of_definition = false;
    while (!end_of_definition) {
        if (isDataDefinitionEnd(tmp)) {
            tmp += 2;
        } else if (IsLineEnd(*tmp)) {
            end_of_definition = true;
        }
        if (!SkipSpaces(&tmp, mEnd) || *tmp == '#') {
            break;
        }
        const bool isNum(IsNumeric(*tmp) || isNanOrInf(tmp));
        SkipToken(tmp, mEnd);
        if (isNum) {
            ++numComponents;
        }
        if (!SkipSpaces(&tmp, mEnd) || *tmp == '#') {
            break;
        }
    }

    return numComponents;
}

size_t ObjFileParser::getTexCoordVector(std::vector<aiVector3D> &point3d_array) {
    size_t numComponents = getNumComponentsInDataDefinition();
    ai_real x, y, z;
    if (2 == numComponents) {
        copyNextWord(m_buffer, Buffersize);
        x = (ai_real)fast_atof(m_buffer);

        copyNextWord(m_buffer, Buffersize);
        y = (ai_real)fast_atof(m_buffer);
        z = 0.0;
    } else if (3 == numComponents) {
        copyNextWord(m_buffer, Buffersize);
        x = (ai_real)fast_atof(m_buffer);

        copyNextWord(m_buffer, Buffersize);
        y = (ai_real)fast_atof(m_buffer);

        copyNextWord(m_buffer, Buffersize);
        z = (ai_real)fast_atof(m_buffer);
    } else {
        throw DeadlyImportError("OBJ: Invalid number of components");
    }

    // Coerce nan and inf to 0 as is the OBJ default value
    if (!std::isfinite(x))
        x = 0;

    if (!std::isfinite(y))
        y = 0;

    if (!std::isfinite(z))
        z = 0;

    point3d_array.emplace_back(x, y, z);
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
    return numComponents;
}

void ObjFileParser::getVector3(std::vector<aiVector3D> &point3d_array) {
    ai_real x, y, z;
    copyNextWord(m_buffer, Buffersize);
    x = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    y = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    z = (ai_real)fast_atof(m_buffer);

    point3d_array.emplace_back(x, y, z);
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

void ObjFileParser::getHomogeneousVector3(std::vector<aiVector3D> &point3d_array) {
    ai_real x, y, z, w;
    copyNextWord(m_buffer, Buffersize);
    x = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    y = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    z = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    w = (ai_real)fast_atof(m_buffer);

    if (w == 0)
        throw DeadlyImportError("OBJ: Invalid component in homogeneous vector (Division by zero)");

    point3d_array.emplace_back(x / w, y / w, z / w);
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

void ObjFileParser::getTwoVectors3(std::vector<aiVector3D> &point3d_array_a, std::vector<aiVector3D> &point3d_array_b) {
    ai_real x, y, z;
    copyNextWord(m_buffer, Buffersize);
    x = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    y = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    z = (ai_real)fast_atof(m_buffer);

    point3d_array_a.emplace_back(x, y, z);

    copyNextWord(m_buffer, Buffersize);
    x = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    y = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    z = (ai_real)fast_atof(m_buffer);

    point3d_array_b.emplace_back(x, y, z);

    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

void ObjFileParser::getVector2(std::vector<aiVector2D> &point2d_array) {
    ai_real x, y;
    copyNextWord(m_buffer, Buffersize);
    x = (ai_real)fast_atof(m_buffer);

    copyNextWord(m_buffer, Buffersize);
    y = (ai_real)fast_atof(m_buffer);

    point2d_array.emplace_back(x, y);

    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

static constexpr char DefaultObjName[] = "defaultobject";

void ObjFileParser::getFace(aiPrimitiveType type) {
    m_DataIt = getNextToken<DataArrayIt>(m_DataIt, m_DataItEnd);
    if (m_DataIt == m_DataItEnd || *m_DataIt == '\0') {
        return;
    }

    ObjFile::Face *face = new ObjFile::Face(type);
    bool hasNormal = false;

    const int vSize = static_cast<unsigned int>(m_pModel->mVertices.size());
    const int vtSize = static_cast<unsigned int>(m_pModel->mTextureCoord.size());
    const int vnSize = static_cast<unsigned int>(m_pModel->mNormals.size());

    const bool vt = (!m_pModel->mTextureCoord.empty());
    const bool vn = (!m_pModel->mNormals.empty());
    int iPos = 0;
    while (m_DataIt < m_DataItEnd) {
        int iStep = 1;

        if (IsLineEnd(*m_DataIt) || *m_DataIt == '#') {
            break;
        }

        if (*m_DataIt == '/') {
            if (type == aiPrimitiveType_POINT) {
                ASSIMP_LOG_ERROR("Obj: Separator unexpected in point statement");
            }
            iPos++;
        } else if (IsSpaceOrNewLine(*m_DataIt)) {
            iPos = 0;
        } else {
            //OBJ USES 1 Base ARRAYS!!!!
            int iVal;
            auto end = m_DataIt;
            // find either the buffer end or the '\0'
            while (end < m_DataItEnd && *end != '\0')
                ++end;
            // avoid temporary string allocation if there is a zero
            if (end != m_DataItEnd) {
                iVal = ::atoi(&(*m_DataIt));
            } else {
                // otherwise make a zero terminated copy, which is safe to pass to atoi
                std::string number(&(*m_DataIt), m_DataItEnd - m_DataIt);
                iVal = ::atoi(number.c_str());
            }

            // increment iStep position based off of the sign and # of digits
            int tmp = iVal;
            if (iVal < 0) {
                ++iStep;
            }
            while ((tmp = tmp / 10) != 0) {
                ++iStep;
            }

            if (iPos == 1 && !vt && vn) {
                iPos = 2; // skip texture coords for normals if there are no tex coords
            }

            if (iVal > 0) {
                // Store parsed index
                if (0 == iPos) {
                    face->m_vertices.push_back(iVal - 1);
                } else if (1 == iPos) {
                    face->m_texturCoords.push_back(iVal - 1);
                } else if (2 == iPos) {
                    face->m_normals.push_back(iVal - 1);
                    hasNormal = true;
                } else {
                    reportErrorTokenInFace();
                }
            } else if (iVal < 0) {
                // Store relatively index
                if (0 == iPos) {
                    face->m_vertices.push_back(vSize + iVal);
                } else if (1 == iPos) {
                    face->m_texturCoords.push_back(vtSize + iVal);
                } else if (2 == iPos) {
                    face->m_normals.push_back(vnSize + iVal);
                    hasNormal = true;
                } else {
                    reportErrorTokenInFace();
                }
            } else {
                //On error, std::atoi will return 0 which is not a valid value
                delete face;
                throw DeadlyImportError("OBJ: Invalid face index.");
            }
        }
        m_DataIt += iStep;
    }

    if (face->m_vertices.empty()) {
        ASSIMP_LOG_ERROR("Obj: Ignoring empty face");
        // skip line and clean up
        m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
        delete face;
        return;
    }

    // Set active material, if one set
    if (nullptr != m_pModel->mCurrentMaterial) {
        face->m_pMaterial = m_pModel->mCurrentMaterial;
    } else {
        face->m_pMaterial = m_pModel->mDefaultMaterial;
    }

    // Create a default object, if nothing is there
    if (nullptr == m_pModel->mCurrentObject) {
        createObject(DefaultObjName);
    }

    // Assign face to mesh
    if (nullptr == m_pModel->mCurrentMesh) {
        createMesh(DefaultObjName);
    }

    // Store the face
    m_pModel->mCurrentMesh->m_Faces.emplace_back(face);
    m_pModel->mCurrentMesh->m_uiNumIndices += static_cast<unsigned int>(face->m_vertices.size());
    m_pModel->mCurrentMesh->m_uiUVCoordinates[0] += static_cast<unsigned int>(face->m_texturCoords.size());
    if (!m_pModel->mCurrentMesh->m_hasNormals && hasNormal) {
        m_pModel->mCurrentMesh->m_hasNormals = true;
    }
    // Skip the rest of the line
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

void ObjFileParser::getMaterialDesc() {
    // Get next data for material data
    m_DataIt = getNextToken<DataArrayIt>(m_DataIt, m_DataItEnd);
    if (m_DataIt == m_DataItEnd) {
        return;
    }

    char *pStart = &(*m_DataIt);
    while (m_DataIt != m_DataItEnd && !IsLineEnd(*m_DataIt)) {
        ++m_DataIt;
    }

    // In some cases we should ignore this 'usemtl' command, this variable helps us to do so
    bool skip = false;

    // Get name
    std::string strName(pStart, &(*m_DataIt));
    strName = ai_trim(strName);
    if (strName.empty()) {
        skip = true;
    }

    // If the current mesh has the same material, we will ignore that 'usemtl' command
    // There is no need to create another object or even mesh here
    if (!skip) {
        if (m_pModel->mCurrentMaterial && m_pModel->mCurrentMaterial->MaterialName == aiString(strName)) {
            skip = true;
        }
    }

    if (!skip) {
        // Search for material
        std::map<std::string, ObjFile::Material *>::iterator it = m_pModel->mMaterialMap.find(strName);
        if (it == m_pModel->mMaterialMap.end()) {
            // Not found, so we don't know anything about the material except for its name.
            // This may be the case if the material library is missing. We don't want to lose all
            // materials if that happens, so create a new named material instead of discarding it
            // completely.
            ASSIMP_LOG_ERROR("OBJ: failed to locate material ", strName, ", creating new material");
            m_pModel->mCurrentMaterial = new ObjFile::Material();
            m_pModel->mCurrentMaterial->MaterialName.Set(strName);
            m_pModel->mMaterialLib.push_back(strName);
            m_pModel->mMaterialMap[strName] = m_pModel->mCurrentMaterial;
        } else {
            // Found, using detected material
            m_pModel->mCurrentMaterial = (*it).second;
        }

        if (needsNewMesh(strName)) {
            auto newMeshName = m_pModel->mActiveGroup.empty() ? strName : m_pModel->mActiveGroup;
            createMesh(newMeshName);
        }

        m_pModel->mCurrentMesh->m_uiMaterialIndex = getMaterialIndex(strName);
    }

    // Skip rest of line
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

// -------------------------------------------------------------------
//  Get a comment, values will be skipped
void ObjFileParser::getComment() {
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

// -------------------------------------------------------------------
//  Get material library from file.
void ObjFileParser::getMaterialLib() {
    // Translate tuple
    m_DataIt = getNextToken<DataArrayIt>(m_DataIt, m_DataItEnd);
    if (m_DataIt == m_DataItEnd) {
        return;
    }

    char *pStart = &(*m_DataIt);
    while (m_DataIt != m_DataItEnd && !IsLineEnd(*m_DataIt)) {
        ++m_DataIt;
    }

    // Check for existence
    const std::string strMatName(pStart, &(*m_DataIt));
    std::string absName;

    // Check if directive is valid.
    if (0 == strMatName.length()) {
        ASSIMP_LOG_WARN("OBJ: no name for material library specified.");
        return;
    }

    if (m_pIO->StackSize() > 0) {
        std::string path = m_pIO->CurrentDirectory();
        if ('/' != *path.rbegin()) {
            path += '/';
        }
        absName += path;
        absName += strMatName;
    } else {
        absName = strMatName;
    }
	
	std::unique_ptr<IOStream> pFile(m_pIO->Open(absName));
    if (nullptr == pFile) {
        ASSIMP_LOG_ERROR("OBJ: Unable to locate material file ", strMatName);
        std::string strMatFallbackName = m_originalObjFileName.substr(0, m_originalObjFileName.length() - 3) + "mtl";
        ASSIMP_LOG_INFO("OBJ: Opening fallback material file ", strMatFallbackName);
        pFile.reset(m_pIO->Open(strMatFallbackName));
        if (!pFile) {
            ASSIMP_LOG_ERROR("OBJ: Unable to locate fallback material file ", strMatFallbackName);
            m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
            return;
        }
    }

    // Import material library data from file.
    // Some exporters (e.g. Silo) will happily write out empty
    // material files if the model doesn't use any materials, so we
    // allow that.
    std::vector<char> buffer;
    BaseImporter::TextFileToBuffer(pFile.get(), buffer, BaseImporter::ALLOW_EMPTY);
    //m_pIO->Close(pFile);

    // Importing the material library
    ObjFileMtlImporter mtlImporter(buffer, strMatName, m_pModel.get());
}

// -------------------------------------------------------------------
//  Set a new material definition as the current material.
void ObjFileParser::getNewMaterial() {
    m_DataIt = getNextToken<DataArrayIt>(m_DataIt, m_DataItEnd);
    m_DataIt = getNextWord<DataArrayIt>(m_DataIt, m_DataItEnd);
    if (m_DataIt == m_DataItEnd) {
        return;
    }

    char *pStart = &(*m_DataIt);
    std::string strMat(pStart, *m_DataIt);
    while (m_DataIt != m_DataItEnd && IsSpaceOrNewLine(*m_DataIt)) {
        ++m_DataIt;
    }
    std::map<std::string, ObjFile::Material *>::iterator it = m_pModel->mMaterialMap.find(strMat);
    if (it == m_pModel->mMaterialMap.end()) {
        // Show a warning, if material was not found
        ASSIMP_LOG_WARN("OBJ: Unsupported material requested: ", strMat);
        m_pModel->mCurrentMaterial = m_pModel->mDefaultMaterial;
    } else {
        // Set new material
        if (needsNewMesh(strMat)) {
            createMesh(strMat);
        }
        m_pModel->mCurrentMesh->m_uiMaterialIndex = getMaterialIndex(strMat);
    }

    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

// -------------------------------------------------------------------
int ObjFileParser::getMaterialIndex(const std::string &strMaterialName) {
    int mat_index = -1;
    if (strMaterialName.empty()) {
        return mat_index;
    }
    for (size_t index = 0; index < m_pModel->mMaterialLib.size(); ++index) {
        if (strMaterialName == m_pModel->mMaterialLib[index]) {
            mat_index = (int)index;
            break;
        }
    }
    return mat_index;
}

// -------------------------------------------------------------------
//  Getter for a group name.
void ObjFileParser::getGroupName() {
    std::string groupName;

    // here we skip 'g ' from line
    m_DataIt = getNextToken<DataArrayIt>(m_DataIt, m_DataItEnd);
    m_DataIt = getName<DataArrayIt>(m_DataIt, m_DataItEnd, groupName);
    if (isEndOfBuffer(m_DataIt, m_DataItEnd)) {
        return;
    }

    // Change active group, if necessary
    if (m_pModel->mActiveGroup != groupName) {
        // Search for already existing entry
        ObjFile::Model::ConstGroupMapIt it = m_pModel->mGroups.find(groupName);

        // We are mapping groups into the object structure
        createObject(groupName);

        // New group name, creating a new entry
        if (it == m_pModel->mGroups.end()) {
            std::vector<unsigned int> *pFaceIDArray = new std::vector<unsigned int>;
            m_pModel->mGroups[groupName] = pFaceIDArray;
            m_pModel->mGroupFaceIDs = (pFaceIDArray);
        } else {
            m_pModel->mGroupFaceIDs = (*it).second;
        }
        m_pModel->mActiveGroup = groupName;
    }
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

// -------------------------------------------------------------------
//  Not supported
void ObjFileParser::getGroupNumber() {
    // Not used

    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

// -------------------------------------------------------------------
//  Not supported
void ObjFileParser::getGroupNumberAndResolution() {
    // Not used

    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}

// -------------------------------------------------------------------
//  Stores values for a new object instance, name will be used to
//  identify it.
void ObjFileParser::getObjectName() {
    m_DataIt = getNextToken<DataArrayIt>(m_DataIt, m_DataItEnd);
    if (m_DataIt == m_DataItEnd) {
        return;
    }
    char *pStart = &(*m_DataIt);
    while (m_DataIt != m_DataItEnd && !IsSpaceOrNewLine(*m_DataIt)) {
        ++m_DataIt;
    }

    std::string strObjectName(pStart, &(*m_DataIt));
    if (!strObjectName.empty()) {
        // Reset current object
        m_pModel->mCurrentObject = nullptr;

        // Search for actual object
        for (std::vector<ObjFile::Object *>::const_iterator it = m_pModel->mObjects.begin();
                it != m_pModel->mObjects.end();
                ++it) {
            if ((*it)->m_strObjName == strObjectName) {
                m_pModel->mCurrentObject = *it;
                break;
            }
        }

        // Allocate a new object, if current one was not found before
        if (nullptr == m_pModel->mCurrentObject) {
            createObject(strObjectName);
        }
    }
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
}
// -------------------------------------------------------------------
//  Creates a new object instance
void ObjFileParser::createObject(const std::string &objName) {
    ai_assert(nullptr != m_pModel);

    m_pModel->mCurrentObject = new ObjFile::Object;
    m_pModel->mCurrentObject->m_strObjName = objName;
    m_pModel->mObjects.push_back(m_pModel->mCurrentObject);

    createMesh(objName);

    if (m_pModel->mCurrentMaterial) {
        m_pModel->mCurrentMesh->m_uiMaterialIndex =
                getMaterialIndex(m_pModel->mCurrentMaterial->MaterialName.data);
        m_pModel->mCurrentMesh->m_pMaterial = m_pModel->mCurrentMaterial;
    }
}
// -------------------------------------------------------------------
//  Creates a new mesh
void ObjFileParser::createMesh(const std::string &meshName) {
    ai_assert(nullptr != m_pModel);

    m_pModel->mCurrentMesh = new ObjFile::Mesh(meshName);
    m_pModel->mMeshes.push_back(m_pModel->mCurrentMesh);
    unsigned int meshId = static_cast<unsigned int>(m_pModel->mMeshes.size() - 1);
    if (nullptr != m_pModel->mCurrentObject) {
        m_pModel->mCurrentObject->m_Meshes.push_back(meshId);
    } else {
        ASSIMP_LOG_ERROR("OBJ: No object detected to attach a new mesh instance.");
    }
}

// -------------------------------------------------------------------
//  Returns true, if a new mesh must be created.
bool ObjFileParser::needsNewMesh(const std::string &materialName) {
    // If no mesh data yet
    if (m_pModel->mCurrentMesh == nullptr) {
        return true;
    }
    bool newMat = false;
    int matIdx = getMaterialIndex(materialName);
    int curMatIdx = m_pModel->mCurrentMesh->m_uiMaterialIndex;
    if (curMatIdx != int(ObjFile::Mesh::NoMaterial) && curMatIdx != matIdx
            // no need create a new mesh if no faces in current
            // lets say 'usemtl' goes straight after 'g'
            && !m_pModel->mCurrentMesh->m_Faces.empty()) {
        // New material -> only one material per mesh, so we need to create a new
        // material
        newMat = true;
    }
    return newMat;
}

// -------------------------------------------------------------------
//  Shows an error in parsing process.
void ObjFileParser::reportErrorTokenInFace() {
    m_DataIt = skipLine<DataArrayIt>(m_DataIt, m_DataItEnd, m_uiLine);
    ASSIMP_LOG_ERROR("OBJ: Not supported token in face description detected");
}

// -------------------------------------------------------------------

} // Namespace Assimp

#endif // !! ASSIMP_BUILD_NO_OBJ_IMPORTER