ModelLoader.hpp

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#ifndef CSCI441_MODEL_LOADER_HPP
#define CSCI441_MODEL_LOADER_HPP
 
#include "modelMaterial.hpp"
 
#ifdef CSCI441_USE_GLEW
    #include <GL/glew.h>
#else
    #include <glad/gl.h>
#endif
 
#include <glm/glm.hpp>
#include <stb_image.h>
 
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <sstream>
#include <map>
#include <string>
#include <utility>
#include <vector>
 
 
namespace CSCI441 {
 
    class [[maybe_unused]] ModelLoader final {
    public:
        ModelLoader();
        [[maybe_unused]] explicit ModelLoader( const char* filename );
        ~ModelLoader();
 
        ModelLoader(const ModelLoader&) = delete;
        ModelLoader& operator=(const ModelLoader&) = delete;
 
        bool loadModelFile( std::string filename, bool INFO = true, bool ERRORS = true );
 
        [[maybe_unused]] void setAttributeLocations(GLint positionLocation, GLint normalLocation = -1, GLint texCoordLocation = -1) const;
 
        [[maybe_unused]] bool draw( GLuint shaderProgramHandle,
                   GLint matDiffLocation = -1, GLint matSpecLocation = -1, GLint matShinLocation = -1, GLint matAmbLocation = -1,
                   GLenum diffuseTexture = GL_TEXTURE0 ) const;
 
        [[maybe_unused]] [[nodiscard]] GLuint getNumberOfVertices() const;
        [[maybe_unused]] [[nodiscard]] GLfloat* getVertices() const;
        [[maybe_unused]] [[nodiscard]] GLfloat* getNormals() const;
        [[maybe_unused]] [[nodiscard]] GLfloat* getTexCoords() const;
        [[maybe_unused]] [[nodiscard]] GLuint getNumberOfIndices() const;
        [[maybe_unused]] [[nodiscard]] GLuint* getIndices() const;
 
        [[maybe_unused]] static void enableAutoGenerateNormals();
        [[maybe_unused]] static void disableAutoGenerateNormals();
 
    private:
        void _init();
        bool _loadMTLFile( const char *mtlFilename, bool INFO, bool ERRORS );
        bool _loadOBJFile( bool INFO, bool ERRORS );
        bool _loadOFFFile( bool INFO, bool ERRORS );
        bool _loadPLYFile( bool INFO, bool ERRORS );
        bool _loadSTLFile( bool INFO, bool ERRORS );
        static std::vector<std::string> _tokenizeString( std::string input, const std::string& delimiters );
        void _allocateAttributeArrays(GLuint numVertices, GLuint numIndices);
        void _bufferData();
 
        std::string _filename;
        CSCI441_INTERNAL::MODEL_TYPE _modelType;
 
        GLuint _vaod;
        GLuint _vbods[2];
 
        glm::vec3* _vertices;
        glm::vec3* _normals;
        glm::vec2* _texCoords;
        GLuint* _indices;
        GLuint _uniqueIndex;
        GLuint _numIndices;
 
        std::map< std::string, CSCI441_INTERNAL::ModelMaterial* > _materials;
        std::map< std::string, std::vector< std::pair< GLuint, GLuint > > > _materialIndexStartStop;
 
        bool _hasVertexTexCoords;
        bool _hasVertexNormals;
 
        static bool sAUTO_GEN_NORMALS;
    };
}
 
 
namespace CSCI441_INTERNAL {
    unsigned char* createTransparentTexture( const unsigned char *imageData, const unsigned char *imageMask, int texWidth, int texHeight, int texChannels, int maskChannels );
    [[maybe_unused]] void flipImageY( int texWidth, int texHeight, int textureChannels, unsigned char *textureData );
}
 
inline bool CSCI441::ModelLoader::sAUTO_GEN_NORMALS = false;
 
inline CSCI441::ModelLoader::ModelLoader() {
    _init();
}
 
[[maybe_unused]]
inline CSCI441::ModelLoader::ModelLoader( const char* filename ) {
    _init();
    loadModelFile( filename );
}
 
inline CSCI441::ModelLoader::~ModelLoader() {
    delete[] _vertices;
    delete[] _normals;
    delete[] _texCoords;
    delete[] _indices;
 
    glDeleteBuffers( 2, _vbods );
    glDeleteVertexArrays( 1, &_vaod );
}
 
inline void CSCI441::ModelLoader::_init() {
    _hasVertexTexCoords = false;
    _hasVertexNormals = false;
 
    _vertices = nullptr;
    _texCoords = nullptr;
    _normals = nullptr;
    _indices = nullptr;
 
    _uniqueIndex = 0;
    _numIndices = 0;
 
    glGenVertexArrays( 1, &_vaod );
    glGenBuffers( 2, _vbods );
}
 
inline bool CSCI441::ModelLoader::loadModelFile( std::string filename, bool INFO, bool ERRORS ) {
    bool result = true;
    _filename = std::move(filename);
    if( _filename.find(".obj") != std::string::npos ) {
        result = _loadOBJFile( INFO, ERRORS );
        _modelType = CSCI441_INTERNAL::MODEL_TYPE::OBJ;
    }
    else if( _filename.find(".off") != std::string::npos ) {
        result = _loadOFFFile( INFO, ERRORS );
        _modelType = CSCI441_INTERNAL::MODEL_TYPE::OFF;
    }
    else if( _filename.find(".ply") != std::string::npos ) {
        result = _loadPLYFile( INFO, ERRORS );
        _modelType = CSCI441_INTERNAL::MODEL_TYPE::PLY;
    }
    else if( _filename.find(".stl") != std::string::npos ) {
        result = _loadSTLFile( INFO, ERRORS );
        _modelType = CSCI441_INTERNAL::MODEL_TYPE::STL;
    }
    else {
        result = false;
        if (ERRORS) fprintf( stderr, "[ERROR]:  Unsupported file format for file: %s\n", _filename.c_str() );
    }
 
    return result;
}
 
[[maybe_unused]]
inline void CSCI441::ModelLoader::setAttributeLocations(GLint positionLocation, GLint normalLocation, GLint texCoordLocation) const {
    glBindVertexArray( _vaod );
    glBindBuffer( GL_ARRAY_BUFFER, _vbods[0] );
 
    glEnableVertexAttribArray( positionLocation );
    glVertexAttribPointer( positionLocation, 3, GL_FLOAT, GL_FALSE, 0, (void*)nullptr );
 
    glEnableVertexAttribArray( normalLocation );
    glVertexAttribPointer( normalLocation, 3, GL_FLOAT, GL_FALSE, 0, (void*)(sizeof(glm::vec3) * _uniqueIndex) );
 
    glEnableVertexAttribArray( texCoordLocation );
    glVertexAttribPointer( texCoordLocation, 2, GL_FLOAT, GL_FALSE, 0, (void*)(sizeof(glm::vec3) * _uniqueIndex * 2) );
}
 
[[maybe_unused]]
inline bool CSCI441::ModelLoader::draw( GLuint shaderProgramHandle,
                                        GLint matDiffLocation, GLint matSpecLocation, GLint matShinLocation, GLint matAmbLocation,
                                        GLenum diffuseTexture ) const {
    glBindVertexArray( _vaod );
 
    bool result = true;
    if( _modelType == CSCI441_INTERNAL::MODEL_TYPE::OBJ ) {
        for(const auto & materialIter : _materialIndexStartStop) {
            auto materialName = materialIter.first;
            auto indexStartStop = materialIter.second;
 
            CSCI441_INTERNAL::ModelMaterial* material = nullptr;
            if( _materials.find( materialName ) != _materials.end() )
                material = _materials.find( materialName )->second;
 
            for(auto & idxIter : indexStartStop) {
                auto start = idxIter.first;
                auto end = idxIter.second;
                GLsizei length = (GLsizei)(end - start) + 1;
 
//              printf( "rendering material %s (%u, %u) = %u\n", materialName.c_str(), start, end, length );
 
                if( material != nullptr ) {
                    glProgramUniform4fv( shaderProgramHandle, matAmbLocation, 1, &material->ambient[0] );
                    glProgramUniform4fv( shaderProgramHandle, matDiffLocation, 1, &material->diffuse[0] );
                    glProgramUniform4fv( shaderProgramHandle, matSpecLocation, 1, &material->specular[0] );
                    glProgramUniform1f( shaderProgramHandle, matShinLocation, material->shininess );
 
                    if( material->map_Kd != -1 ) {
                        glActiveTexture( diffuseTexture );
                        glBindTexture( GL_TEXTURE_2D, material->map_Kd );
                    }
                }
 
                glDrawElements( GL_TRIANGLES, length, GL_UNSIGNED_INT, (void*)(sizeof(GLuint)*start) );
            }
        }
    } else {
        glDrawElements( GL_TRIANGLES, static_cast<GLint>(_numIndices), GL_UNSIGNED_INT, (void*)nullptr );
    }
 
    return result;
}
 
[[maybe_unused]] inline GLuint CSCI441::ModelLoader::getNumberOfVertices() const { return _uniqueIndex; }
[[maybe_unused]] inline GLfloat* CSCI441::ModelLoader::getVertices() const { return (_vertices != nullptr ? (GLfloat*)&_vertices[0] : nullptr); }
[[maybe_unused]] inline GLfloat* CSCI441::ModelLoader::getNormals() const { return (_normals != nullptr ? (GLfloat*)&_normals[0] : nullptr); }
[[maybe_unused]] inline GLfloat* CSCI441::ModelLoader::getTexCoords() const { return (_texCoords != nullptr ? (GLfloat*)&_texCoords[0] : nullptr); }
[[maybe_unused]] inline GLuint CSCI441::ModelLoader::getNumberOfIndices() const { return _numIndices; }
[[maybe_unused]] inline GLuint* CSCI441::ModelLoader::getIndices() const { return _indices; }
 
// Read in a WaveFront *.obj File
inline bool CSCI441::ModelLoader::_loadOBJFile( bool INFO, bool ERRORS ) {
    bool result = true;
 
    if ( INFO ) fprintf( stdout, "[.obj]: -=-=-=-=-=-=-=- BEGIN %s Info -=-=-=-=-=-=-=- \n", _filename.c_str() );
 
    time_t start, end;
    time(&start);
 
    std::ifstream in( _filename );
    if( !in.is_open() ) {
        if (ERRORS) fprintf( stderr, "[.obj]: [ERROR]: Could not open \"%s\"\n", _filename.c_str() );
        if ( INFO ) fprintf( stdout, "[.obj]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=- \n", _filename.c_str() );
        return false;
    }
 
    GLuint numObjects = 0, numGroups = 0;
    GLuint numVertices = 0, numTexCoords = 0, numNormals = 0;
    GLuint numFaces = 0, numTriangles = 0;
    glm::vec3 minDimension = {999999.f, 999999.f, 999999.f};
    glm::vec3 maxDimension = { -999999.f, -999999.f, -999999.f };
    std::string line;
 
    std::map<std::string, GLuint> uniqueCounts;
    _uniqueIndex = 0;
 
    int progressCounter = 0;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " \t" );
        if( tokens.empty() ) continue;
 
        //the line should have a single character that lets us know if it's a...
        if( tokens[0] == "#"  || tokens[0].find_first_of('#') == 0 ) {
            // comment ignore
        } else if( tokens[0] == "o" ) {                     // object name ignore
            numObjects++;
        } else if( tokens[0] == "g" ) {                     // polygon group name ignore
            numGroups++;
        } else if( tokens[0] == "mtllib" ) {                    // material library
            _loadMTLFile( tokens[1].c_str(), INFO, ERRORS );
        } else if( tokens[0] == "v" ) {                     //vertex
            numVertices++;
 
            glm::vec3 pos = { strtof( tokens[1].c_str(), nullptr ),
                            strtof( tokens[2].c_str(), nullptr ),
                            strtof( tokens[3].c_str(), nullptr ) };
 
            if( pos.x < minDimension.x ) minDimension.x = pos.x;
            if( pos.x > maxDimension.x ) maxDimension.x = pos.x;
            if( pos.y < minDimension.y ) minDimension.y = pos.y;
            if( pos.y > maxDimension.y ) maxDimension.y = pos.y;
            if( pos.z < minDimension.z ) minDimension.z = pos.z;
            if( pos.z > maxDimension.z ) maxDimension.z = pos.z;
        } else if( tokens[0] == "vn" ) {                    //vertex normal
            numNormals++;
        } else if( tokens[0] == "vt" ) {                    //vertex tex coord
            numTexCoords++;
        } else if( tokens[0] == "f" ) {                     //face!
            //now, faces can be either quads or triangles (or maybe more?)
            //split the string on spaces to get the number of vertices+attributes.
            std::vector<std::string> faceTokens = _tokenizeString(line, " ");
 
            for (GLuint i = 1; i < faceTokens.size(); i++) {
                //need to use both the tokens and number of slashes to determine what info is there.
                std::vector<std::string> groupTokens = _tokenizeString(faceTokens[i], "/");
                int numSlashes = 0;
                for (char j: faceTokens[i]) {
                    if (j == '/') numSlashes++;
                }
 
                std::stringstream currentFaceTokenStream;
 
                auto signedVertexIndex = (GLint) strtol(groupTokens[0].c_str(), nullptr, 10);
                GLuint vertexIndex = signedVertexIndex;
                if (signedVertexIndex < 0) vertexIndex = numVertices + signedVertexIndex + 1;
 
                currentFaceTokenStream << vertexIndex;
 
                //based on combination of number of tokens and slashes, we can determine what we have.
                if (groupTokens.size() == 2 && numSlashes == 1) {
                    _hasVertexTexCoords = true;
 
                    auto signedTexCoordIndex = (GLint) strtol(groupTokens[1].c_str(), nullptr, 10);
                    GLuint texCoordIndex = signedTexCoordIndex;
                    if (signedTexCoordIndex < 0) texCoordIndex = numTexCoords + signedTexCoordIndex + 1;
 
                    currentFaceTokenStream << "/" << texCoordIndex;
                } else if (groupTokens.size() == 2 && numSlashes == 2) {
                    _hasVertexNormals = true;
 
                    auto signedNormalIndex = (GLint) strtol(groupTokens[1].c_str(), nullptr, 10);
                    GLuint normalIndex = signedNormalIndex;
                    if (signedNormalIndex < 0) normalIndex = numNormals + signedNormalIndex + 1;
 
                    currentFaceTokenStream << "//" << normalIndex;
                } else if (groupTokens.size() == 3) {
                    _hasVertexTexCoords = true;
                    _hasVertexNormals = true;
 
                    auto signedTexCoordIndex = (GLint) strtol(groupTokens[1].c_str(), nullptr, 10);
                    GLuint texCoordIndex = signedTexCoordIndex;
                    if (signedTexCoordIndex < 0) texCoordIndex = numTexCoords + signedTexCoordIndex + 1;
 
                    auto signedNormalIndex = (GLint) strtol(groupTokens[2].c_str(), nullptr, 10);
                    GLuint normalIndex = signedNormalIndex;
                    if (signedNormalIndex < 0) normalIndex = numNormals + signedNormalIndex + 1;
 
                    currentFaceTokenStream << "/" << texCoordIndex << "/" << normalIndex;
                } else if (groupTokens.size() != 1) {
                    if (ERRORS) fprintf(stderr, "[.obj]: [ERROR]: Malformed OBJ file, %s.\n", _filename.c_str());
                    return false;
                }
 
                std::string processedFaceToken = currentFaceTokenStream.str();
                if (uniqueCounts.find(processedFaceToken) == uniqueCounts.end()) {
                    uniqueCounts.insert(std::pair<std::string, long int>(processedFaceToken, _uniqueIndex));
                    _uniqueIndex++;
                }
            }
 
            numTriangles += (faceTokens.size() - 1 - 3 + 1);
 
            numFaces++;
        } else if( tokens[0] == "usemtl" ) {                            // use material library
 
        } else {
            if (INFO) printf( "[.obj]: ignoring line: %s\n", line.c_str() );
        }
 
        if (INFO) {
            progressCounter++;
            if( progressCounter % 5000 == 0 ) {
                printf("\33[2K\r");
                switch( progressCounter ) {
                    case 5000:  printf("[.obj]: scanning %s...\\", _filename.c_str());  break;
                    case 10000: printf("[.obj]: scanning %s...|", _filename.c_str());   break;
                    case 15000: printf("[.obj]: scanning %s.../", _filename.c_str());   break;
                    case 20000: printf("[.obj]: scanning %s...-", _filename.c_str());   break;
                    default: break;
                }
                fflush(stdout);
            }
            if( progressCounter == 20000 )
                progressCounter = 0;
        }
    }
    in.close();
 
    if (INFO) {
        printf( "\33[2K\r" );
        printf( "[.obj]: scanning %s...done!\n", _filename.c_str() );
        printf( "[.obj]: ------------\n" );
        printf( "[.obj]: Model Stats:\n" );
        printf( "[.obj]: Vertices:  \t%u\tNormals:  \t%u\tTex Coords:\t%u\n", numVertices, numNormals, numTexCoords );
        printf( "[.obj]: Unique Verts:\t%u\n", _uniqueIndex );
        printf( "[.obj]: Faces:     \t%u\tTriangles:\t%u\n", numFaces, numTriangles );
        printf( "[.obj]: Objects:   \t%u\tGroups:   \t%u\n", numObjects, numGroups );
 
        glm::vec3 sizeDimensions = maxDimension - minDimension;
        printf( "[.obj]: Dimensions:\t(%f, %f, %f)\n", sizeDimensions.x, sizeDimensions.y, sizeDimensions.z );
    }
 
    if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
        if (INFO && !_hasVertexNormals)
            printf( "[.obj]: [WARN]: No vertex normals exist on model.  To autogenerate vertex\n\tnormals, call CSCI441::ModelLoader::enableAutoGenerateNormals()\n\tprior to loading the model file.\n" );
        _allocateAttributeArrays(_uniqueIndex, numTriangles*3);
    } else {
        if (INFO) printf( "[.obj]: No vertex normals exist on model, vertex normals will be autogenerated\n" );
        _allocateAttributeArrays(numTriangles * 3, numTriangles*3);
    }
 
    auto objVertices  = new glm::vec3[numVertices];
    auto objNormals   = new glm::vec3[numNormals];
    auto objTexCoords = new glm::vec2[numTexCoords];
 
    std::vector<glm::vec3> verticesTemps;
    std::vector<glm::vec2> texCoordsTemp;
 
    printf( "[.obj]: ------------\n" );
 
    uniqueCounts.clear();
    _uniqueIndex = 0;
    _numIndices = 0;
 
    in.open( _filename );
 
    GLuint verticesSeen = 0, texCoordsSeen = 0, normalsSeen = 0, indicesSeen = 0;
    GLuint uniqueNumVertices = 0;
 
    std::string currentMaterial = "default";
    _materialIndexStartStop.insert( std::pair< std::string, std::vector< std::pair< GLuint, GLuint > > >( currentMaterial, std::vector< std::pair< GLuint, GLuint > >(1) ) );
    _materialIndexStartStop.find( currentMaterial )->second.back().first = indicesSeen;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        auto tokens = _tokenizeString( line, " \t" );
        if( tokens.empty() ) continue;
 
        //the line should have a single character that lets us know if it's a...
        if( tokens[0] == "#" || tokens[0].find_first_of('#') == 0   // comment ignore
            || tokens[0] == "o"                                         // object name ignore
            || tokens[0] == "g"                                         // polygon group name ignore
            || tokens[0] == "mtllib"                                    // material library
            || tokens[0] == "s"                                         // smooth shading
        ) {
 
        } else if( tokens[0] == "usemtl" ) {                            // use material library
            if( currentMaterial == "default" && indicesSeen == 0 ) {
                _materialIndexStartStop.clear();
            } else {
                _materialIndexStartStop.find( currentMaterial )->second.back().second = indicesSeen - 1;
            }
            currentMaterial = tokens[1];
            if( _materialIndexStartStop.find( currentMaterial ) == _materialIndexStartStop.end() ) {
                _materialIndexStartStop.insert( std::pair< std::string, std::vector< std::pair< GLuint, GLuint > > >( currentMaterial, std::vector< std::pair< GLuint, GLuint > >(1) ) );
                _materialIndexStartStop.find( currentMaterial )->second.back().first = indicesSeen;
            } else {
                _materialIndexStartStop.find( currentMaterial )->second.emplace_back(  indicesSeen, -1 );
            }
        } else if( tokens[0] == "v" ) {                     //vertex
            objVertices[verticesSeen++] = glm::vec3(strtof(tokens[1].c_str(), nullptr ),
                                                    strtof( tokens[2].c_str(), nullptr ),
                                                    strtof( tokens[3].c_str(), nullptr ) );
        } else if( tokens[0] == "vn" ) {                    //vertex normal
            objNormals[normalsSeen++] = glm::vec3(strtof(tokens[1].c_str(), nullptr ),
                                                  strtof( tokens[2].c_str(), nullptr ),
                                                  strtof( tokens[3].c_str(), nullptr ));
        } else if( tokens[0] == "vt" ) {                    //vertex tex coord
            objTexCoords[texCoordsSeen++] = glm::vec2(strtof(tokens[1].c_str(), nullptr ),
                                                      strtof( tokens[2].c_str(), nullptr ));
        } else if( tokens[0] == "f" ) {                     //face!
            std::vector<std::string> processedFaceTokens;
 
            bool faceHasVertexNormals = false;
            bool faceHasTextureCoordinates = false;
 
            for(GLuint i = 1; i < tokens.size(); i++) {
                //need to use both the tokens and number of slashes to determine what info is there.
                auto vertexAttributeTokens = _tokenizeString(tokens[i], "/");
                int numAttributeSlashes = 0;
                for(char j : tokens[i]) {
                    if(j == '/') numAttributeSlashes++;
                }
 
                GLuint vertexIndex = 0, texCoordIndex = 0, normalIndex = 0;
 
                std::stringstream currentFaceTokenStream;
                auto signedVertexIndex = (GLint)strtol(vertexAttributeTokens[0].c_str(), nullptr, 10);
                vertexIndex = signedVertexIndex;
                if(signedVertexIndex < 0) vertexIndex = verticesSeen + signedVertexIndex + 1;
                currentFaceTokenStream << vertexIndex;
 
                //based on combination of number of tokens and slashes, we can determine what we have.
                if(vertexAttributeTokens.size() == 2 && numAttributeSlashes == 1) {
                    // v/t
                    _hasVertexTexCoords = true;
                    faceHasTextureCoordinates = true;
 
                    auto signedTexCoordIndex = (GLint)strtol(vertexAttributeTokens[1].c_str(), nullptr, 10);
                    texCoordIndex = signedTexCoordIndex;
                    if(signedTexCoordIndex < 0) texCoordIndex = texCoordsSeen + signedTexCoordIndex + 1;
                    currentFaceTokenStream << "/" << texCoordIndex;
                } else if(vertexAttributeTokens.size() == 2 && numAttributeSlashes == 2) {
                    // v//n
                    _hasVertexNormals = true;
                    faceHasVertexNormals = true;
 
                    auto signedNormalIndex = (GLint)strtol(vertexAttributeTokens[1].c_str(), nullptr, 10);
                    normalIndex = signedNormalIndex;
                    if(signedNormalIndex < 0) normalIndex = normalsSeen + signedNormalIndex + 1;
                    currentFaceTokenStream << "//" << normalIndex;
                } else if(vertexAttributeTokens.size() == 3) {
                    // v/t/n
                    _hasVertexTexCoords = true;
                    faceHasTextureCoordinates = true;
                    _hasVertexNormals = true;
                    faceHasVertexNormals = true;
 
                    auto signedTexCoordIndex = (GLint)strtol(vertexAttributeTokens[1].c_str(), nullptr, 10);
                    texCoordIndex = signedTexCoordIndex;
                    if(signedTexCoordIndex < 0) texCoordIndex = texCoordsSeen + signedTexCoordIndex + 1;
 
                    auto signedNormalIndex = (GLint)strtol(vertexAttributeTokens[2].c_str(), nullptr, 10);
                    normalIndex = signedNormalIndex;
                    if(signedNormalIndex < 0) normalIndex = normalsSeen + signedNormalIndex + 1;
 
                    currentFaceTokenStream << "/" << texCoordIndex << "/" << normalIndex;
                } else if(vertexAttributeTokens.size() != 1) {
                    if (ERRORS) fprintf(stderr, "[.obj]: [ERROR]: Malformed OBJ file, %s.\n", _filename.c_str());
                    return false;
                }
 
                auto processedFaceToken = currentFaceTokenStream.str();
                processedFaceTokens.push_back(processedFaceToken);
 
                // check if we've seen this attribute combination before
                if( uniqueCounts.find( processedFaceToken ) == uniqueCounts.end() ) {
                    // if not, add it to the list
                    uniqueCounts.insert( std::pair<std::string,GLuint>(processedFaceToken, uniqueNumVertices) );
 
                    if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
                        _vertices[ _uniqueIndex ] = objVertices[ vertexIndex - 1 ];
                        if(faceHasTextureCoordinates && texCoordIndex != 0) { _texCoords[ _uniqueIndex ] = objTexCoords[ texCoordIndex - 1 ]; }
                        if(faceHasVertexNormals && normalIndex != 0) _normals[ _uniqueIndex ] = objNormals[ normalIndex - 1 ];
                        _uniqueIndex++;
                    } else {
                        verticesTemps.push_back( objVertices[ vertexIndex - 1 ] );
                        if(faceHasTextureCoordinates && texCoordIndex != 0) { texCoordsTemp.push_back( objTexCoords[ texCoordIndex - 1 ] ); }
 
                        if( (vertexAttributeTokens.size() == 2 && numAttributeSlashes == 2)
                            || (vertexAttributeTokens.size() == 3) ) {
                            // should not occur if no normals
                            if (ERRORS) fprintf( stderr, "[.obj]: [ERROR]: no vertex normals were specified, should not be trying to access values\n" );
                        }
                    }
                    uniqueNumVertices++;
                }
            }
 
            for(GLuint i = 1; i < processedFaceTokens.size()-1; i++) {
                if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
                    _indices[ indicesSeen++ ] = uniqueCounts.find( processedFaceTokens[0]   )->second;
                    _indices[ indicesSeen++ ] = uniqueCounts.find( processedFaceTokens[i]   )->second;
                    _indices[ indicesSeen++ ] = uniqueCounts.find( processedFaceTokens[i+1] )->second;
 
                    _numIndices += 3;
                } else {
                    GLuint aI = uniqueCounts.find( processedFaceTokens[0]   )->second;
                    GLuint bI = uniqueCounts.find( processedFaceTokens[i]   )->second;
                    GLuint cI = uniqueCounts.find( processedFaceTokens[i+1] )->second;
 
                    glm::vec3 a = verticesTemps[aI];
                    glm::vec3 b = verticesTemps[bI];
                    glm::vec3 c = verticesTemps[cI];
 
                    glm::vec3 ab = b - a; glm::vec3 ac = c - a;
                    glm::vec3 ba = a - b; glm::vec3 bc = c - b;
                    glm::vec3 ca = a - c; glm::vec3 cb = b - c;
 
                    glm::vec3 aN = glm::normalize( glm::cross( ab, ac ) );
                    glm::vec3 bN = glm::normalize( glm::cross( bc, ba ) );
                    glm::vec3 cN = glm::normalize( glm::cross( ca, cb ) );
 
                    _vertices[ _uniqueIndex ] = a;
                    _normals[ _uniqueIndex ] = aN;
                    if( faceHasTextureCoordinates && _hasVertexTexCoords ) { _texCoords[ _uniqueIndex ] = texCoordsTemp[ aI ]; }
                    _indices[ _numIndices++ ] = _uniqueIndex++;
 
                    indicesSeen++;
 
                    _vertices[ _uniqueIndex ] = b;
                    _normals[ _uniqueIndex ] = bN;
                    if( faceHasTextureCoordinates && _hasVertexTexCoords ) { _texCoords[ _uniqueIndex ] = texCoordsTemp[ bI ]; }
                    _indices[ _numIndices++ ] = _uniqueIndex++;
 
                    indicesSeen++;
 
                    _vertices[ _uniqueIndex ] = c;
                    _normals[ _uniqueIndex ] = cN;
                    if( faceHasTextureCoordinates && _hasVertexTexCoords ) { _texCoords[ _uniqueIndex ] = texCoordsTemp[ cI ]; }
                    _indices[ _numIndices++ ] = _uniqueIndex++;
 
                    indicesSeen++;
                }
            }
        }
 
        if (INFO) {
            progressCounter++;
            if( progressCounter % 5000 == 0 ) {
                printf("\33[2K\r");
                switch( progressCounter ) {
                    case 5000:  printf("[.obj]: parsing %s...\\", _filename.c_str());   break;
                    case 10000: printf("[.obj]: parsing %s...|", _filename.c_str());    break;
                    case 15000: printf("[.obj]: parsing %s.../", _filename.c_str());    break;
                    case 20000: printf("[.obj]: parsing %s...-", _filename.c_str());    break;
                    default: break;
                }
                fflush(stdout);
            }
            if( progressCounter == 20000 )
                progressCounter = 0;
        }
    }
 
    in.close();
 
    if (INFO) {
        printf( "\33[2K\r" );
        printf( "[.obj]: parsing %s...done!\n", _filename.c_str() );
    }
 
    _materialIndexStartStop.find( currentMaterial )->second.back().second = indicesSeen - 1;
 
    _bufferData();
 
    time(&end);
    double seconds = difftime( end, start );
 
    if (INFO) {
        printf( "[.obj]: Completed in %.3fs\n", seconds );
        printf( "[.obj]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=- \n\n", _filename.c_str() );
    }
 
    return result;
}
 
inline bool CSCI441::ModelLoader::_loadMTLFile( const char* mtlFilename, bool INFO, bool ERRORS ) {
    bool result = true;
 
    if (INFO) printf( "[.mtl]: -*-*-*-*-*-*-*- BEGIN %s Info -*-*-*-*-*-*-*-\n", mtlFilename );
 
    std::string line;
    std::string path;
    if( _filename.find('/') != std::string::npos ) {
        path = _filename.substr( 0, _filename.find_last_of('/')+1 );
    } else {
        path = "./";
    }
 
    std::ifstream in;
    in.open( mtlFilename );
    if( !in.is_open() ) {
        std::string folderMtlFile = path + mtlFilename;
        in.open( folderMtlFile.c_str() );
        if( !in.is_open() ) {
            if (ERRORS) fprintf( stderr, "[.mtl]: [ERROR]: could not open material file: %s\n", mtlFilename );
            if ( INFO ) printf( "[.mtl]: -*-*-*-*-*-*-*-  END %s Info  -*-*-*-*-*-*-*-\n", mtlFilename );
            return false;
        }
    }
 
    CSCI441_INTERNAL::ModelMaterial* currentMaterial = nullptr;
    std::string materialName;
 
    unsigned char *textureData = nullptr;
    unsigned char *maskData = nullptr;
    unsigned char *fullData;
    int texWidth, texHeight, textureChannels = 1, maskChannels = 1;
    GLuint textureHandle = 0;
 
    std::map< std::string, GLuint > imageHandles;
 
    int numMaterials = 0;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " /" );
        if( tokens.empty() ) continue;
 
        //the line should have a single character that lets us know if it's a...
        if( tokens[0] == "#" ) {                            // comment
            // ignore
        } else if( tokens[0] == "newmtl" ) {                //new material
            if (INFO) printf( "[.mtl]: Parsing material %s properties\n", tokens[1].c_str() );
            currentMaterial = new CSCI441_INTERNAL::ModelMaterial();
            materialName = tokens[1];
            _materials.insert( std::pair<std::string, CSCI441_INTERNAL::ModelMaterial*>( materialName, currentMaterial ) );
 
            textureHandle = 0;
            textureData = nullptr;
            maskData = nullptr;
            textureChannels = 1;
            maskChannels = 1;
 
            numMaterials++;
        } else if( tokens[0] == "Ka" ) {                    // ambient component
            currentMaterial->ambient[0] = strtof( tokens[1].c_str(), nullptr );
            currentMaterial->ambient[1] = strtof( tokens[2].c_str(), nullptr );
            currentMaterial->ambient[2] = strtof( tokens[3].c_str(), nullptr );
        } else if( tokens[0] == "Kd" ) {                    // diffuse component
            currentMaterial->diffuse[0] = strtof( tokens[1].c_str(), nullptr );
            currentMaterial->diffuse[1] = strtof( tokens[2].c_str(), nullptr );
            currentMaterial->diffuse[2] = strtof( tokens[3].c_str(), nullptr );
        } else if( tokens[0] == "Ks" ) {                    // specular component
            currentMaterial->specular[0] = strtof( tokens[1].c_str(), nullptr );
            currentMaterial->specular[1] = strtof( tokens[2].c_str(), nullptr );
            currentMaterial->specular[2] = strtof( tokens[3].c_str(), nullptr );
        } else if( tokens[0] == "Ke" ) {                    // emissive component
            currentMaterial->emissive[0] = strtof( tokens[1].c_str(), nullptr );
            currentMaterial->emissive[1] = strtof( tokens[2].c_str(), nullptr );
            currentMaterial->emissive[2] = strtof( tokens[3].c_str(), nullptr );
        } else if( tokens[0] == "Ns" ) {                    // shininess component
            currentMaterial->shininess = strtof( tokens[1].c_str(), nullptr );
        } else if( tokens[0] == "Tr"
                    || tokens[0] == "d" ) {                 // transparency component - Tr or d can be used depending on the format
            currentMaterial->ambient[3] = strtof( tokens[1].c_str(), nullptr );
            currentMaterial->diffuse[3] = strtof( tokens[1].c_str(), nullptr );
            currentMaterial->specular[3] = strtof( tokens[1].c_str(), nullptr );
        } else if( tokens[0] == "illum" ) {                 // illumination type component
            // TODO illumination type?
        } else if( tokens[0] == "map_Kd" ) {                // diffuse color texture map
            if( imageHandles.find( tokens[1] ) != imageHandles.end() ) {
                // _textureHandles->insert( pair< string, GLuint >( materialName, imageHandles.find( tokens[1] )->second ) );
                currentMaterial->map_Kd = imageHandles.find( tokens[1] )->second;
            } else {
                stbi_set_flip_vertically_on_load(true);
                textureData = stbi_load( tokens[1].c_str(), &texWidth, &texHeight, &textureChannels, 0 );
                if( !textureData ) {
                    std::string folderName = path + tokens[1];
                    textureData = stbi_load( folderName.c_str(), &texWidth, &texHeight, &textureChannels, 0 );
                }
 
                if( !textureData ) {
                    if (ERRORS) fprintf( stderr, "[.mtl]: [ERROR]: File Not Found: %s\n", tokens[1].c_str() );
                } else {
                    if (INFO) printf( "[.mtl]: TextureMap:\t%s\tSize: %dx%d\tColors: %d\n", tokens[1].c_str(), texWidth, texHeight, textureChannels );
 
                    if( maskData == nullptr ) {
                        if( textureHandle == 0 ) {
                            glGenTextures( 1, &textureHandle );
                            imageHandles.insert( std::pair<std::string, GLuint>( tokens[1], textureHandle ) );
                        }
 
                        glBindTexture( GL_TEXTURE_2D, textureHandle );
 
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 
                        GLint colorSpace = GL_RGB;
                        if( textureChannels == 4 )
                            colorSpace = GL_RGBA;
                        glTexImage2D( GL_TEXTURE_2D, 0, colorSpace, texWidth, texHeight, 0, colorSpace, GL_UNSIGNED_BYTE, textureData );
 
                        currentMaterial->map_Kd = textureHandle;
                    } else {
                        fullData = CSCI441_INTERNAL::createTransparentTexture( textureData, maskData, texWidth, texHeight, textureChannels, maskChannels );
 
                        if( textureHandle == 0 ) {
                            glGenTextures( 1, &textureHandle );
                            imageHandles.insert( std::pair<std::string, GLuint>( tokens[1], textureHandle ) );
                        }
 
                        glBindTexture( GL_TEXTURE_2D, textureHandle );
 
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 
                        glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, texWidth, texHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, fullData );
 
                        delete[] fullData;
 
                        currentMaterial->map_Kd = textureHandle;
                    }
                }
            }
        } else if( tokens[0] == "map_d" ) {             // alpha texture map
            if( imageHandles.find( tokens[1] ) != imageHandles.end() ) {
                // _textureHandles->insert( pair< string, GLuint >( materialName, imageHandles.find( tokens[1] )->second ) );
                currentMaterial->map_d = imageHandles.find( tokens[1] )->second;
            } else {
                stbi_set_flip_vertically_on_load(true);
                maskData = stbi_load( tokens[1].c_str(), &texWidth, &texHeight, &textureChannels, 0 );
                if( !textureData ) {
                    std::string folderName = path + tokens[1];
                    maskData = stbi_load( folderName.c_str(), &texWidth, &texHeight, &textureChannels, 0 );
                }
 
                if( !maskData ) {
                    if (ERRORS) fprintf( stderr, "[.mtl]: [ERROR]: File Not Found: %s\n", tokens[1].c_str() );
                } else {
                    if (INFO) printf( "[.mtl]: AlphaMap:  \t%s\tSize: %dx%d\tColors: %d\n", tokens[1].c_str(), texWidth, texHeight, maskChannels );
 
                    if( textureData != nullptr ) {
                        fullData = CSCI441_INTERNAL::createTransparentTexture( textureData, maskData, texWidth, texHeight, textureChannels, maskChannels );
 
                        if( textureHandle == 0 ) {
                            glGenTextures( 1, &textureHandle );
                            imageHandles.insert( std::pair<std::string, GLuint>( tokens[1], textureHandle ) );
                        }
 
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
                        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
 
                        glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, texWidth, texHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, fullData );
 
                        delete[] fullData;
 
                        currentMaterial->map_Kd = textureHandle;
                    }
                }
            }
        } else if( tokens[0] == "map_Ka" ) {                    // ambient color texture map
          // TODO ambient color map?
        } else if( tokens[0] == "map_Ks" ) {                    // specular color texture map
          // TODO specular color map?
        } else if( tokens[0] == "map_Ns" ) {                    // specular highlight map (shininess map)
          // TODO specular highlight map?
        } else if( tokens[0] == "Ni" ) {                        // optical density / index of refraction
          // TODO index of refraction?
        } else if( tokens[0] == "Tf" ) {                        // transmission filter
          // TODO transmission filter?
        } else if( tokens[0] == "bump"
                    || tokens[0] == "map_bump" ) {              // bump map
          // TODO bump map?
        } else {
            if (INFO) printf( "[.mtl]: ignoring line: %s\n", line.c_str() );
        }
    }
 
    in.close();
 
    if ( INFO ) {
        printf( "[.mtl]: Materials:\t%d\n", numMaterials );
        printf( "[.mtl]: -*-*-*-*-*-*-*-  END %s Info  -*-*-*-*-*-*-*-\n", mtlFilename );
    }
 
    return result;
}
 
inline bool CSCI441::ModelLoader::_loadOFFFile( bool INFO, bool ERRORS ) {
    bool result = true;
 
    if (INFO ) printf( "[.off]: -=-=-=-=-=-=-=- BEGIN %s Info -=-=-=-=-=-=-=-\n", _filename.c_str() );
 
    time_t start, end;
    time(&start);
 
    std::ifstream in( _filename );
    if( !in.is_open() ) {
        if (ERRORS) fprintf( stderr, "[.off]: [ERROR]: Could not open \"%s\"\n", _filename.c_str() );
        if ( INFO ) printf( "[.off]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
        return false;
    }
 
    GLuint numVertices = 0, numFaces = 0, numTriangles = 0;
    GLfloat minX = 999999.0f, maxX = -999999.0f, minY = 999999.0f, maxY = -999999.0f, minZ = 999999.0f, maxZ = -999999.0f;
    std::string line;
 
    enum OFF_FILE_STATE { HEADER, VERTICES, FACES, DONE };
 
    OFF_FILE_STATE fileState = HEADER;
 
    GLuint vSeen = 0, fSeen = 0;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " \t" );
        if( tokens.empty() ) continue;
 
        //the line should have a single character that lets us know if it's a...
        if( tokens[0] == "#" || tokens[0].find_first_of('#') == 0 ) {                               // comment ignore
        } else if( fileState == HEADER ) {
            if( tokens[0] == "OFF" ) {                  // denotes OFF File type
            } else {
                if( tokens.size() != 3 ) {
                    if (ERRORS) fprintf( stderr, "[.off]: [ERROR]: Malformed OFF file.  # vertices, faces, edges not properly specified\n" );
                    if ( INFO ) printf( "[.off]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
                    in.close();
                    return false;
                }
                // read in number of expected vertices, faces, and edges
                numVertices = (GLuint)strtol( tokens[0].c_str(), nullptr, 10 );
                numFaces = (GLuint)strtol( tokens[1].c_str(), nullptr, 10 );
 
                // ignore tokens[2] - number of edges -- unnecessary information
                // numEdges = (GLuint)strtol( tokens[2].c_str(), nullptr, 10 );
 
                fileState = VERTICES;
            }
        } else if( fileState == VERTICES ) {
            // read in x y z vertex location
            GLfloat x = strtof( tokens[0].c_str(), nullptr ),
                    y = strtof( tokens[1].c_str(), nullptr ),
                    z = strtof( tokens[2].c_str(), nullptr );
 
            if( x < minX ) minX = x;
            if( x > maxX ) maxX = x;
            if( y < minY ) minY = y;
            if( y > maxY ) maxY = y;
            if( z < minZ ) minZ = z;
            if( z > maxZ ) maxZ = z;
 
            vSeen++;
            if( vSeen == numVertices )
                fileState = FACES;
        } else if( fileState == FACES ) {
            auto numberOfVerticesInFace = (GLuint)strtol( tokens[0].c_str(), nullptr, 10 );
 
            numTriangles += numberOfVerticesInFace - 3 + 1;
 
            if( fSeen == numFaces )
                fileState = DONE;
        } else {
            if (INFO) printf( "[.off]: unknown file state: %d\n", fileState );
        }
    }
    in.close();
 
    if (INFO) {
        printf( "\33[2K\r" );
        printf( "[.off]: scanning %s...done!\n", _filename.c_str() );
        printf( "[.off]: ------------\n" );
        printf( "[.off]: Model Stats:\n" );
        printf( "[.off]: Vertices:  \t%u\tNormals:   \t%u\tTex Coords:\t%u\n", numVertices, 0, 0 );
        printf( "[.off]: Faces:     \t%u\tTriangles: \t%u\n", numFaces, numTriangles );
        printf( "[.off]: Dimensions:\t(%f, %f, %f)\n", (maxX - minX), (maxY - minY), (maxZ - minZ) );
    }
 
    if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
        if (INFO && !_hasVertexNormals)
            printf( "[.off]: [WARN]: No vertex normals exist on model.  To autogenerate vertex\n\tnormals, call CSCI441::ModelLoader::enableAutoGenerateNormals()\n\tprior to loading the model file.\n" );
        _allocateAttributeArrays(numVertices, numTriangles*3);
    } else {
        if (INFO) printf( "[.off]: No vertex normals exist on model, vertex normals will be autogenerated\n" );
        _allocateAttributeArrays(numTriangles*3, numTriangles*3);
    }
 
    std::vector<glm::vec3> verticesTemp;
 
    if (INFO) printf( "[.off]: ------------\n" );
 
    in.open( _filename );
 
    _uniqueIndex = 0;
    _numIndices = 0;
    vSeen = 0;
 
    fileState = HEADER;
 
    int progressCounter = 0;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " \t" );
        if( tokens.empty() ) continue;
 
        //the line should have a single character that lets us know if it's a...
        if( tokens[0] == "#"  || tokens[0].find_first_of('#') == 0 ) {
            // comment ignore
        } else if( fileState == HEADER ) {
            if( tokens[0] == "OFF" ) {
                // denotes OFF File type
            } else {
                // end of OFF Header reached
                fileState = VERTICES;
            }
        } else if( fileState == VERTICES ) {
            // read in x y z vertex location
            glm::vec3 pos(strtof( tokens[0].c_str(), nullptr ),
                          strtof( tokens[1].c_str(), nullptr ),
                          strtof( tokens[2].c_str(), nullptr ) );
 
            // check if RGB(A) color information is associated with vertex
            if( tokens.size() == 6 || tokens.size() == 7 ) {
                // TODO: handle RGBA color info
//               glm::vec4 color(strtof( tokens[3].c_str(), nullptr ),
//                                 strtof( tokens[4].c_str(), nullptr ),
//                                 strtof( tokens[5].c_str(), nullptr ),
//                                 (tokens.size() == 7 ? strtof( tokens[6].c_str(), nullptr ) : 1.0f) );
            }
 
            if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
                _vertices[ _uniqueIndex ] = pos;
                _uniqueIndex++;
            } else {
                verticesTemp.push_back(pos);
                vSeen++;
            }
            // if all vertices have been read in, move on to faces
            if( _uniqueIndex == numVertices || vSeen == numVertices )
                fileState = FACES;
        } else if( fileState == FACES ) {
            auto numberOfVerticesInFace = (GLuint)strtol( tokens[0].c_str(), nullptr, 10 );
 
            // read in each vertex index of the face
            for(GLuint i = 2; i <= numberOfVerticesInFace - 1; i++) {
                if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
                    auto fanRoot = strtol( tokens[1].c_str(), nullptr, 10 );
                    auto fanA = strtol( tokens[i].c_str(), nullptr, 10 );
                    auto fanB = strtol( tokens[i+1].c_str(), nullptr, 10 );
 
                    if( fanRoot < 0 ) fanRoot = numVertices + fanRoot + 1;
                    if( fanA < 0 ) fanA = numVertices + fanA + 1;
                    if( fanB < 0 ) fanB = numVertices + fanB + 1;
 
                    //regardless, we always get a vertex index.
                    _indices[ _numIndices++ ] = fanRoot;
                    _indices[ _numIndices++ ] = fanA;
                    _indices[ _numIndices++ ] = fanB;
                } else {
                    auto aI = strtol( tokens[1].c_str(), nullptr, 10 );
                    auto bI = strtol( tokens[i].c_str(), nullptr, 10 );
                    auto cI = strtol( tokens[i+1].c_str(), nullptr, 10 );
 
                    if( aI < 0 ) aI = numVertices + aI + 1;
                    if( bI < 0 ) bI = numVertices + bI + 1;
                    if( cI < 0 ) cI = numVertices + cI + 1;
 
                    glm::vec3 a = verticesTemp[aI];
                    glm::vec3 b = verticesTemp[bI];
                    glm::vec3 c = verticesTemp[cI];
 
                    glm::vec3 ab = b - a; glm::vec3 ac = c - a;
                    glm::vec3 ba = a - b; glm::vec3 bc = c - b;
                    glm::vec3 ca = a - c; glm::vec3 cb = b - c;
 
                    glm::vec3 aN = glm::normalize( glm::cross( ab, ac ) );
                    glm::vec3 bN = glm::normalize( glm::cross( bc, ba ) );
                    glm::vec3 cN = glm::normalize( glm::cross( ca, cb ) );
 
                    _vertices[ _uniqueIndex ] = a;
                    _normals[ _uniqueIndex ] = aN;
                    _indices[ _numIndices++ ] = _uniqueIndex++;
 
                    _vertices[ _uniqueIndex ] = b;
                    _normals[ _uniqueIndex ] = bN;
                    _indices[ _numIndices++ ] = _uniqueIndex++;
 
                    _vertices[ _uniqueIndex ] = c;
                    _normals[ _uniqueIndex ] = cN;
                    _indices[ _numIndices++ ] = _uniqueIndex++;
                }
            }
 
            // check if RGB(A) color information is associated with face
            // TODO: handle color info
            //some local variables to hold the vertex+attribute indices we read in.
            //we do it this way because we'll have to split quads into triangles ourselves.
            // GLfloat color[4] = {-1,-1,-1,1};
            // if( tokens.size() == numberOfVerticesInFace + 4 || tokens.size() == numberOfVerticesInFace + 5 ) {
            //  color[0] = atof( tokens[numberOfVerticesInFace + 1].c_str() );
            //  color[1] = atof( tokens[numberOfVerticesInFace + 2].c_str() );
            //  color[2] = atof( tokens[numberOfVerticesInFace + 3].c_str() );
            //  color[3] = 1;
      //
            //  if( tokens.size() == numberOfVerticesInFace + 5 )
            //      color[3] = atof( tokens[numberOfVerticesInFace + 4].c_str() );
            // }
 
        } else {
 
        }
 
        if (INFO) {
            progressCounter++;
            if( progressCounter % 5000 == 0 ) {
                printf("\33[2K\r");
                switch( progressCounter ) {
                    case 5000:  printf("[.off]: parsing %s...\\", _filename.c_str());   break;
                    case 10000: printf("[.off]: parsing %s...|", _filename.c_str());    break;
                    case 15000: printf("[.off]: parsing %s.../", _filename.c_str());    break;
                    case 20000: printf("[.off]: parsing %s...-", _filename.c_str());    break;
                    default: break;
                }
                fflush(stdout);
            }
            if( progressCounter == 20000 )
                progressCounter = 0;
        }
    }
    in.close();
 
    _bufferData();
 
    time(&end);
    double seconds = difftime( end, start );
 
    if (INFO) {
        printf( "\33[2K\r" );
        printf( "[.off]: parsing %s...done!  (Time: %.1fs)\n", _filename.c_str(), seconds );
        printf( "[.off]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
    }
 
    return result;
}
 
// notes on PLY format: http://paulbourke.net/dataformats/ply/
inline bool CSCI441::ModelLoader::_loadPLYFile( bool INFO, bool ERRORS ) {
    bool result = true;
 
    if (INFO ) printf( "[.ply]: -=-=-=-=-=-=-=- BEGIN %s Info -=-=-=-=-=-=-=-\n", _filename.c_str() );
 
    time_t start, end;
    time(&start);
 
    std::ifstream in( _filename );
    if( !in.is_open() ) {
        if (ERRORS) fprintf( stderr, "[.ply]: [ERROR]: Could not open \"%s\"\n", _filename.c_str() );
        if ( INFO ) printf( "[.ply]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
        return false;
    }
 
    GLuint numVertices = 0, numFaces = 0, numTriangles = 0, numMaterials = 0;
    GLfloat minX = 999999.0f, maxX = -999999.0f, minY = 999999.0f, maxY = -999999.0f, minZ = 999999.0f, maxZ = -999999.0f;
    std::string line;
 
    enum PLY_FILE_STATE { HEADER, VERTICES, FACES, MATERIALS };
    enum PLY_ELEMENT_TYPE { NONE, VERTEX, FACE, MATERIAL };
 
    PLY_FILE_STATE fileState = HEADER;
    PLY_ELEMENT_TYPE elemType = NONE;
 
    GLuint progressCounter = 0;
    GLuint vSeen = 0;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " \t" );
 
        if( tokens.empty() ) continue;
 
        //the line should have a single character that lets us know if it's a...
        if( tokens[0] == "comment" ) {                              // comment ignore
        } else if( fileState == HEADER ) {
            if( tokens[0] == "ply" ) {                  // denotes ply File type
            } else if( tokens[0] == "format" ) {
                if( tokens[1] != "ascii" ) {
                    if (ERRORS) fprintf( stderr, "[.ply]: [ERROR]: File \"%s\" not ASCII format\n", _filename.c_str() );
                    if ( INFO ) printf( "[.ply]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
                    in.close();
                    return false;
                }
            } else if( tokens[0] == "element" ) {       // an element (vertex, face, material)
                if( tokens[1] == "vertex" ) {
                    numVertices = (GLuint)strtol( tokens[2].c_str(), nullptr, 10 );
                    elemType = VERTEX;
                } else if( tokens[1] == "face" ) {
                    numFaces = (GLuint)strtol( tokens[2].c_str(), nullptr, 10 );
                    elemType = FACE;
                } else if( tokens[1] == "edge" ) {
 
                } else if( tokens[1] == "material" ) {
                    numMaterials = (GLuint)strtol( tokens[2].c_str(), nullptr, 10 );
                    elemType = MATERIAL;
                } else {
 
                }
            } else if( tokens[0] == "property" ) {
                if( elemType == VERTEX ) {
 
                } else if( elemType == FACE ) {
 
                } else if( elemType == MATERIAL ) {
 
                }
            } else if( tokens[0] == "end_header" ) {    // end of the header section
                fileState = VERTICES;
            }
        } else if( fileState == VERTICES ) {
            // read in x y z vertex location
            auto x = (GLfloat) strtof( tokens[0].c_str(), nullptr ),
                 y = (GLfloat) strtof( tokens[1].c_str(), nullptr ),
                 z = (GLfloat) strtof( tokens[2].c_str(), nullptr );
 
            if( x < minX ) minX = x;
            if( x > maxX ) maxX = x;
            if( y < minY ) minY = y;
            if( y > maxY ) maxY = y;
            if( z < minZ ) minZ = z;
            if( z > maxZ ) maxZ = z;
 
            vSeen++;
            // if all vertices have been read in, move on to faces
            if( vSeen == numVertices )
                fileState = FACES;
        } else if( fileState == FACES ) {
            auto numberOfVerticesInFace = (GLuint)strtol( tokens[0].c_str(), nullptr, 10);
            numTriangles += numberOfVerticesInFace - 3 + 1;
        } else {
            if (INFO) printf( "[.ply]: unknown file state: %d\n", fileState );
        }
 
        if (INFO) {
            progressCounter++;
            if( progressCounter % 5000 == 0 ) {
                printf("\33[2K\r");
                switch( progressCounter ) {
                    case 5000:  printf("[.ply]: scanning %s...\\", _filename.c_str());  break;
                    case 10000: printf("[.ply]: scanning %s...|", _filename.c_str());   break;
                    case 15000: printf("[.ply]: scanning %s.../", _filename.c_str());   break;
                    case 20000: printf("[.ply]: scanning %s...-", _filename.c_str());   break;
                    default: break;
                }
                fflush(stdout);
            }
            if( progressCounter == 20000 )
                progressCounter = 0;
        }
    }
    in.close();
 
    if (INFO) {
        printf( "\33[2K\r" );
        printf( "[.ply]: scanning %s...done!\n", _filename.c_str() );
        printf( "[.ply]: ------------\n" );
        printf( "[.ply]: Model Stats:\n" );
        printf( "[.ply]: Vertices:  \t%u\tNormals:   \t%u\tTex Coords:\t%u\n", numVertices, 0, 0 );
        printf( "[.ply]: Faces:     \t%u\tTriangles: \t%u\n", numFaces, numTriangles );
        printf( "[.ply]: Dimensions:\t(%f, %f, %f)\n", (maxX - minX), (maxY - minY), (maxZ - minZ) );
    }
 
    if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
        if (INFO && !_hasVertexNormals)
            printf( "[.ply]: [WARN]: No vertex normals exist on model.  To autogenerate vertex\n\tnormals, call CSCI441::ModelLoader::enableAutoGenerateNormals()\n\tprior to loading the model file.\n" );
        _allocateAttributeArrays(numVertices, numTriangles*3);
    } else {
        if (INFO) printf( "[.ply]: No vertex normals exist on model, vertex normals will be autogenerated\n" );
        _allocateAttributeArrays(numTriangles*3, numTriangles*3);
    }
 
    if (INFO) printf( "[.ply]: ------------\n" );
 
    std::vector<glm::vec3> verticesTemp;
 
    in.open( _filename );
 
    _uniqueIndex = 0;
    _numIndices = 0;
 
    fileState = HEADER;
    elemType = NONE;
 
    progressCounter = 0;
    vSeen = 0;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " \t" );
 
        if( tokens.empty() ) continue;
 
        //the line should have a single character that lets us know if it's a...
        if( tokens[0] == "comment" ) {                              // comment ignore
        } else if( fileState == HEADER ) {
            if( tokens[0] == "ply" ) {                  // denotes ply File type
            } else if( tokens[0] == "format" ) {
                if( tokens[1] != "ascii" ) {
                    if (ERRORS) fprintf( stderr, "[.ply]: [ERROR]: File \"%s\" not ASCII format\n", _filename.c_str() );
                    if ( INFO ) printf( "[.ply]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
                    in.close();
                    return false;
                }
            } else if( tokens[0] == "element" ) {       // an element (vertex, face, material)
                if( tokens[1] == "vertex" ) {
                    numVertices = (GLuint)strtol( tokens[2].c_str(), nullptr, 10 );
                    elemType = VERTEX;
                } else if( tokens[1] == "face" ) {
                    numFaces = (GLuint)strtol( tokens[2].c_str(), nullptr, 10 );
                    elemType = FACE;
                } else if( tokens[1] == "edge" ) {
 
                } else if( tokens[1] == "material" ) {
                    numMaterials = (GLuint)strtol( tokens[2].c_str(), nullptr, 10 );
                    elemType = MATERIAL;
                } else {
 
                }
            } else if( tokens[0] == "property" ) {
                if( elemType == VERTEX ) {
 
                } else if( elemType == FACE ) {
 
                } else if( elemType == MATERIAL ) {
 
                }
            } else if( tokens[0] == "end_header" ) {    // end of the header section
                fileState = VERTICES;
            }
        } else if( fileState == VERTICES ) {
            // read in x y z vertex location
            glm::vec3 pos(strtof( tokens[0].c_str(), nullptr ),
                          strtof( tokens[1].c_str(), nullptr ),
                          strtof( tokens[2].c_str(), nullptr ) );
 
            if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
                _vertices[ _uniqueIndex ] = pos;
                _uniqueIndex++;
            } else {
                verticesTemp.push_back(pos );
                vSeen++;
            }
            // if all vertices have been read in, move on to faces
            if( _uniqueIndex == numVertices || vSeen == numVertices )
                fileState = FACES;
        } else if( fileState == FACES ) {
            auto numberOfVerticesInFace = (GLuint)strtol( tokens[0].c_str(), nullptr, 10 );
 
            for( GLuint i = 2; i <= numberOfVerticesInFace - 1; i++ ) {
                if( _hasVertexNormals || !sAUTO_GEN_NORMALS ) {
                    _indices[ _numIndices++ ] = (GLuint)strtol( tokens[1].c_str(), nullptr, 10 );
                    _indices[ _numIndices++ ] = (GLuint)strtol( tokens[i].c_str(), nullptr, 10 );
                    _indices[ _numIndices++ ] = (GLuint)strtol( tokens[i+1].c_str(), nullptr, 10 );
                } else {
                    auto aI = (GLuint)strtol( tokens[1].c_str(), nullptr, 10 );
                    auto bI = (GLuint)strtol( tokens[i].c_str(), nullptr, 10 );
                    auto cI = (GLuint)strtol( tokens[i+1].c_str(), nullptr, 10 );
 
                    glm::vec3 a = verticesTemp[aI];
                    glm::vec3 b = verticesTemp[bI];
                    glm::vec3 c = verticesTemp[cI];
 
                    glm::vec3 ab = b - a; glm::vec3 ac = c - a;
                    glm::vec3 ba = a - b; glm::vec3 bc = c - b;
                    glm::vec3 ca = a - c; glm::vec3 cb = b - c;
 
                    glm::vec3 aN = glm::normalize( glm::cross( ab, ac ) );
                    glm::vec3 bN = glm::normalize( glm::cross( bc, ba ) );
                    glm::vec3 cN = glm::normalize( glm::cross( ca, cb ) );
 
                    _vertices[ _uniqueIndex ] = a;
                    _normals[ _uniqueIndex ] = aN;
                    _indices[ _numIndices++ ] = _uniqueIndex++;
 
                    _vertices[ _uniqueIndex ] = b;
                    _normals[ _uniqueIndex ] = bN;
                    _indices[ _numIndices++ ] = _uniqueIndex++;
 
                    _vertices[ _uniqueIndex ] = c;
                    _normals[ _uniqueIndex ] = cN;
                    _indices[ _numIndices++ ] = _uniqueIndex++;
                }
            }
        } else {
            if (INFO) printf( "[.ply]: unknown file state: %d\n", fileState );
        }
 
        if (INFO) {
            progressCounter++;
            if( progressCounter % 5000 == 0 ) {
                printf("\33[2K\r");
                switch( progressCounter ) {
                    case 5000:  printf("[.ply]: parsing %s...\\", _filename.c_str());   break;
                    case 10000: printf("[.ply]: parsing %s...|", _filename.c_str());    break;
                    case 15000: printf("[.ply]: parsing %s.../", _filename.c_str());    break;
                    case 20000: printf("[.ply]: parsing %s...-", _filename.c_str());    break;
                    default: break;
                }
                fflush(stdout);
            }
            if( progressCounter == 20000 )
                progressCounter = 0;
        }
    }
    in.close();
 
    _bufferData();
 
    time(&end);
    double seconds = difftime( end, start );
 
    if (INFO) {
        printf( "\33[2K\r" );
        printf( "[.ply]: parsing %s...done!\n[.ply]: Time to complete: %.3fs\n", _filename.c_str(), seconds );
        printf( "[.ply]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
    }
 
    return result;
}
 
inline bool CSCI441::ModelLoader::_loadSTLFile( bool INFO, bool ERRORS ) {
    bool result = true;
 
    if (INFO) printf( "[.stl]: -=-=-=-=-=-=-=- BEGIN %s Info -=-=-=-=-=-=-=-\n", _filename.c_str() );
 
    time_t start, end;
    time(&start);
 
    std::ifstream in( _filename );
    if( !in.is_open() ) {
        if (ERRORS) fprintf(stderr, "[.stl]: [ERROR]: Could not open \"%s\"\n", _filename.c_str() );
        if ( INFO ) printf( "[.stl]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
        return false;
    }
 
    GLuint numVertices = 0, numNormals = 0, numFaces = 0, numTriangles = 0, numVertsInLoop = 0;
    GLfloat minX = 999999.0f, maxX = -999999.0f, minY = 999999.0f, maxY = -999999.0f, minZ = 999999.0f, maxZ = -999999.0f;
    std::string line;
 
    int progressCounter = 0;
    glm::vec3 normalVector = {0.f,0.f,0.f};
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " \t" );
 
        if( tokens.empty() ) continue;
 
        if( tokens[0] == "solid" ) {
 
        } else if( tokens[0] == "facet" ) {
            // read in x y z triangle normal
            numNormals++;
        } else if( tokens[0] == "outer" && tokens[1] == "loop" ) {
            // begin a primitive
            numVertsInLoop = 0;
        } else if( tokens[0] == "vertex" ) {
            GLfloat x = strtof( tokens[1].c_str(), nullptr ),
                    y = strtof( tokens[2].c_str(), nullptr ),
                    z = strtof( tokens[3].c_str(), nullptr );
 
            if( x < minX ) minX = x;
            if( x > maxX ) maxX = x;
            if( y < minY ) minY = y;
            if( y > maxY ) maxY = y;
            if( z < minZ ) minZ = z;
            if( z > maxZ ) maxZ = z;
 
            numVertices++;
            numVertsInLoop++;
        } else if( tokens[0] == "endloop" ) {
            // end primitive
            numTriangles += numVertsInLoop - 3 + 1;
        } else if( tokens[0] == "endfacet" ) {
            numFaces++;
        } else if( tokens[0] == "endsolid" ) {
 
        }
        else {
            if( memchr( line.c_str(), '\0', line.length() ) != nullptr ) {
                if (ERRORS) fprintf( stderr, "[.stl]: [ERROR]: Cannot read binary STL file \"%s\"\n", _filename.c_str() );
                if ( INFO ) printf( "[.stl]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
                in.close();
                return false;
            } else if (INFO) printf( "[.stl]: unknown line: %s\n", line.c_str() );
        }
 
        if (INFO) {
            progressCounter++;
            if( progressCounter % 5000 == 0 ) {
                printf("\33[2K\r");
                switch( progressCounter ) {
                    case 5000:  printf("[.stl]: scanning %s...\\", _filename.c_str());  break;
                    case 10000: printf("[.stl]: scanning %s...|", _filename.c_str());   break;
                    case 15000: printf("[.stl]: scanning %s.../", _filename.c_str());   break;
                    case 20000: printf("[.stl]: scanning %s...-", _filename.c_str());   break;
                    default: break;
                }
                fflush(stdout);
            }
            if( progressCounter == 20000 )
                progressCounter = 0;
        }
    }
    in.close();
 
    if (INFO) {
        printf( "\33[2K\r" );
        printf( "[.stl]: scanning %s...done!\n", _filename.c_str() );
        printf( "[.stl]: ------------\n" );
        printf( "[.stl]: Model Stats:\n" );
        printf( "[.stl]: Vertices:  \t%u\tNormals:   \t%u\tTex Coords:\t%u\n", numVertices, numNormals, 0 );
        printf( "[.stl]: Faces:     \t%u\tTriangles: \t%u\n", numFaces, numTriangles );
        printf( "[.stl]: Dimensions:\t(%f, %f, %f)\n", (maxX - minX), (maxY - minY), (maxZ - minZ) );
    }
 
    _allocateAttributeArrays(numVertices, numTriangles*3);
 
    if (INFO) printf( "[.stl]: ------------\n" );
 
    in.open( _filename );
 
    _uniqueIndex = 0;
    _numIndices = 0;
 
    while( getline( in, line ) ) {
        if( line.length() > 1 && line.at(0) == '\t' )
            line = line.substr( 1 );
        line.erase( line.find_last_not_of( " \n\r\t" ) + 1 );
 
        std::vector< std::string > tokens = _tokenizeString( line, " \t" );
 
        if( tokens.empty() ) continue;
 
        if( tokens[0] == "solid" ) {
 
        } else if( tokens[0] == "facet" ) {
            // read in x y z triangle normal
            normalVector = glm::vec3( strtof( tokens[2].c_str(), nullptr ),
                                      strtof( tokens[3].c_str(), nullptr ),
                                      strtof( tokens[4].c_str(), nullptr ) );
        } else if( tokens[0] == "outer" && tokens[1] == "loop" ) {
            // begin a primitive
        } else if( tokens[0] == "vertex" ) {
            _vertices[ _uniqueIndex ] = glm::vec3(strtof( tokens[1].c_str(), nullptr ),
                                                  strtof( tokens[2].c_str(), nullptr ),
                                                  strtof( tokens[3].c_str(), nullptr ) );
            _normals[ _uniqueIndex ] = normalVector;
            _indices[ _numIndices++ ] = _uniqueIndex++;
        } else if( tokens[0] == "endloop" ) {
            // end primitive
        } else if( tokens[0] == "endfacet" ) {
 
        } else if( tokens[0] == "endsolid" ) {
 
        }
        else {
 
        }
 
        if (INFO) {
            progressCounter++;
            if( progressCounter % 5000 == 0 ) {
                printf("\33[2K\r");
                switch( progressCounter ) {
                    case 5000:  printf("[.stl]: parsing %s...\\", _filename.c_str());   break;
                    case 10000: printf("[.stl]: parsing %s...|", _filename.c_str());    break;
                    case 15000: printf("[.stl]: parsing %s.../", _filename.c_str());    break;
                    case 20000: printf("[.stl]: parsing %s...-", _filename.c_str());    break;
                    default: break;
                }
                fflush(stdout);
            }
            if( progressCounter == 20000 )
                progressCounter = 0;
        }
    }
    in.close();
 
    _bufferData();
 
    time(&end);
    double seconds = difftime( end, start );
 
    if (INFO) {
        printf("\33[2K\r");
        printf("[.stl]: parsing %s...done!\n[.stl]: Time to complete: %.3fs\n", _filename.c_str(), seconds);
        printf( "[.stl]: -=-=-=-=-=-=-=-  END %s Info  -=-=-=-=-=-=-=-\n\n", _filename.c_str() );
    }
 
    return result;
}
 
[[maybe_unused]]
inline void CSCI441::ModelLoader::enableAutoGenerateNormals() {
    sAUTO_GEN_NORMALS = true;
}
 
[[maybe_unused]]
inline void CSCI441::ModelLoader::disableAutoGenerateNormals() {
    sAUTO_GEN_NORMALS = false;
}
 
inline void CSCI441::ModelLoader::_allocateAttributeArrays(const GLuint numVertices, const GLuint numIndices) {
    _vertices  = new glm::vec3[numVertices];
    _normals   = new glm::vec3[numVertices];
    _texCoords = new glm::vec2[numVertices];
    _indices   = new GLuint[numIndices];
}
 
inline void CSCI441::ModelLoader::_bufferData() {
    glBindVertexArray( _vaod );
 
    glBindBuffer( GL_ARRAY_BUFFER, _vbods[0] );
    glBufferData( GL_ARRAY_BUFFER, static_cast<GLsizeiptr>((sizeof(glm::vec3)*2 + sizeof(glm::vec2)) * _uniqueIndex), nullptr, GL_STATIC_DRAW );
    glBufferSubData( GL_ARRAY_BUFFER, 0, static_cast<GLsizeiptr>(sizeof(glm::vec3) * _uniqueIndex), _vertices );
    glBufferSubData( GL_ARRAY_BUFFER, static_cast<GLintptr>(sizeof(glm::vec3) * _uniqueIndex), static_cast<GLsizeiptr>(sizeof(glm::vec3) * _uniqueIndex), _normals );
    glBufferSubData( GL_ARRAY_BUFFER, static_cast<GLintptr>(sizeof(glm::vec3) * _uniqueIndex * 2), static_cast<GLsizeiptr>(sizeof(glm::vec2) * _uniqueIndex), _texCoords );
 
    glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, _vbods[1] );
    glBufferData( GL_ELEMENT_ARRAY_BUFFER, static_cast<GLsizeiptr>(sizeof(GLuint) * _numIndices), _indices, GL_STATIC_DRAW );
}
 
//
//  vector<string> tokenizeString(string input, string delimiters)
//
//      This is a helper function to break a single string into std::vector
//  of strings, based on a given set of delimiter characters.
//
inline std::vector<std::string> CSCI441::ModelLoader::_tokenizeString(std::string input, const std::string& delimiters) {
    if(input.empty())
        return {};
 
    std::vector<std::string> retVec = std::vector<std::string>();
    size_t oldR = 0, r = 0;
 
    //strip all delimiter characters from the front and end of the input string.
    std::string strippedInput;
    GLint lowerValidIndex = 0, upperValidIndex = (GLint)input.size() - 1;
    while((GLuint)lowerValidIndex < input.size() && delimiters.find_first_of(input.at(lowerValidIndex), 0) != std::string::npos)
        lowerValidIndex++;
 
    while(upperValidIndex >= 0 && delimiters.find_first_of(input.at(upperValidIndex), 0) != std::string::npos)
        upperValidIndex--;
 
    //if the lowest valid index is higher than the highest valid index, they're all delimiters! return nothing.
    if((GLuint)lowerValidIndex >= input.size() || upperValidIndex < 0 || lowerValidIndex > upperValidIndex)
        return {};
 
    //remove the delimiters from the beginning and end of the string, if any.
    strippedInput = input.substr(lowerValidIndex, upperValidIndex-lowerValidIndex+1);
 
    //search for each instance of a delimiter character, and create a new token spanning
    //from the last valid character up to the delimiter character.
    while((r = strippedInput.find_first_of(delimiters, oldR)) != std::string::npos)
    {
        if(oldR != r)           //but watch out for multiple consecutive delimiters!
            retVec.push_back(strippedInput.substr(oldR, r-oldR));
        oldR = r+1;
    }
    if(r != 0)
        retVec.push_back(strippedInput.substr(oldR, r-oldR));
 
    return retVec;
}
 
inline unsigned char* CSCI441_INTERNAL::createTransparentTexture( const unsigned char * imageData, const unsigned char *imageMask, int texWidth, int texHeight, int texChannels, int maskChannels ) {
    //combine the 'mask' array with the image data array into an RGBA array.
    auto *fullData = new unsigned char[texWidth*texHeight*4];
 
    for(int j = 0; j < texHeight; j++) {
        for(int i = 0; i < texWidth; i++) {
            if( imageData ) {
                fullData[(j*texWidth+i)*4+0] = imageData[(j*texWidth+i)*texChannels+0]; // R
                fullData[(j*texWidth+i)*4+1] = imageData[(j*texWidth+i)*texChannels+1]; // G
                fullData[(j*texWidth+i)*4+2] = imageData[(j*texWidth+i)*texChannels+2]; // B
            } else {
                fullData[(j*texWidth+i)*4+0] = 1;   // R
                fullData[(j*texWidth+i)*4+1] = 1;   // G
                fullData[(j*texWidth+i)*4+2] = 1;   // B
            }
 
            if( imageMask ) {
                fullData[(j*texWidth+i)*4+3] = imageMask[(j*texWidth+i)*maskChannels+0];    // A
            } else {
                fullData[(j*texWidth+i)*4+3] = 1;   // A
            }
        }
    }
    return fullData;
}
 
[[maybe_unused]]
inline void CSCI441_INTERNAL::flipImageY( int texWidth, int texHeight, int textureChannels, unsigned char *textureData ) {
    for( int j = 0; j < texHeight / 2; j++ ) {
        for( int i = 0; i < texWidth; i++ ) {
            for( int k = 0; k < textureChannels; k++ ) {
                int top = (j*texWidth + i)*textureChannels + k;
                int bot = ((texHeight-j-1)*texWidth + i)*textureChannels + k;
 
                unsigned char t = textureData[top];
                textureData[top] = textureData[bot];
                textureData[bot] = t;
 
            }
        }
    }
}
 
#endif // __CSCI441_MODEL_LOADER_HPP__