# Blender3D v245 OBJ File: 
# www.blender3d.org

v 1.000000 -1.000000 -1.000000
v 1.000000 -1.000000 1.000000
v -1.000000 -1.000000 1.000000
v -1.000000 -1.000000 -1.000000
v 1.000000 1.000000 -1.000000
v 0.999999 1.000000 1.000001
v -1.000000 1.000000 1.000000
v -1.000000 1.000000 -1.000000
f 5 1 4
f 5 4 8
f 3 7 8
f 3 8 4
f 2 6 3
f 6 7 3
f 1 5 2
f 5 6 2
f 5 8 6
f 8 7 6
f 1 2 3
f 1 3 4

#include <vector>
#include <sstream>

using namespace std;

string getWord(string Line, int Pos)
{
    vector<string> Vec;
    stringstream ss(Line);
    string Word, a;
    while(ss >> Word)
    Vec.push_back(Word);

    if(Pos > Vec.size()-1) //Check whether it's in range
        return "";

    else
    {
        try { a = Vec.at(Pos); } //Just to be safe
        catch(...) { a = ""; } //I'm not sure what to catch
        return a; //Return the word
    }
}

int convertToInt(string Num)
{
    istringstream i(Num);
    int x;

    if(!(i >> x))
        throw 0;

    return x;
}

float convertToFloat(string Num)
{
    istringstream i(Num);
    float x;

    if(!(i >> x))
        throw 0;

    return x;
}

struct Vector {
    float x, y, z;
};

struct Vertex {
    Vector Pos;
    Vector Normal;
};

struct Triangle {
    int v1, v2, v3; //One for each of our corners!
};

class Model
{

    private: //So we can't change them willy nilly
        Triangle Triangles[50000]; //As .obj files don't tell us how many faces
                                   //we have, we have to take a guess, feel free to change the amount for
                                  //bigger models, the most I've come across is 130k
        Vertex Verticies[50000];  //Same as above
        int TriangleCount; //Keep track of the amount of triangles we have
        int VertexCount; //Keep track of the amount of Vertices we have
        int NormalCount; //Keep track of the amount of normals we have
        bool Loaded; //So we know whether it's been loaded of not

public: //So we can access the functions
        Model(); //Constructor
        int Load(const char* Filename);//The function to load, it's int so we can exit the function easily if there's an error!
        void Draw(void); //The function to draw
};

Model::Model()
{
    VertexCount = 1; //Start on 1
    TriangleCount = 1; //Start on 1
    NormalCount = 1; //Start on 1
    Loaded = false; //We haven't loaded a model yet!
}

int Model::Load(const char *Filename)
{

    ifstream F; //Our file
    string Line; //The current line of the file

    F.open(Filename, ios::in);
    if(F.fail()) //Has it failed to open
    {
        cout << "Error opening \"" << Filename << "\"" << endl; //Send an error message
        return 0; //Exit the function
    }

if(Loaded) //If loaded is true
    {
        VertexCount = 1; //Reset
        TriangleCount = 1; //Reset
        NormalCount = 1; //Reset
    }

    while(!F.eof())
    {

getline(F, Line);

if(getWord(Line, 0) == "v") //If the first word is v
        {

            if(VertexCount > 50000) break; //If we're exceeding our 50000 we'd better stop
            Verticies[VertexCount].Pos.x = convertToFloat(getWord(Line, 1)); //Set our x location to the second word of the line.
            Verticies[VertexCount].Pos.y = convertToFloat(getWord(Line, 2)); //Set our y variable to the thrid word of the line.
            Verticies[VertexCount].Pos.z = convertToFloat(getWord(Line, 3)); //Set our z variable to the fourth word of the line.
            VertexCount++; //Next vertex please!

        }
        else if(getWord(Line, 0) == "vn") //If it wasn't v is it vn?
        {
            if(NormalCount > 50000) break; //Are we about to exceed the limit?
            Verticies[NormalCount].Normal.x = convertToFloat(getWord(Line, 1));
            Verticies[NormalCount].Normal.y = convertToFloat(getWord(Line, 2));
            Verticies[NormalCount].Normal.z = convertToFloat(getWord(Line, 3));
            NormalCount++; //Next Normal Please!
        }
        else if(getWord(Line, 0) == "f") //If it wasn't v or vn then is it a face?
        {
            if(TriangleCount > 50000) break; //Check to see if we're exceeding limit again
            Triangles[TriangleCount].v1 = convertToInt(getWord(Line, 1));
            Triangles[TriangleCount].v2 = convertToInt(getWord(Line, 2));
            Triangles[TriangleCount].v3 = convertToInt(getWord(Line, 3));
            TriangleCount++; //Next triangle please!
        }
} //Close Loop!

    F.close();
    Loaded = true;
    cout << "Triangles: " << TriangleCount-1 << endl;
    cout << "Vertecies: " << VertexCount-1 << endl;
    cout << "Normals: " << NormalCount-1 << endl;
}

void Model::Draw(void) //declare our function
{
    if(Loaded) //Check if it's loaded!
    {

glBegin(GL_TRIANGLES); //Say we're using triangles!
        for(int i = 1; i < TriangleCount; i++) //For each face
        {
            glNormal3f(Verticies[Triangles[i].v1].Normal.x, Verticies[Triangles[i].v1].Normal.y, Verticies[Triangles[i].v1].Normal.z);
            glVertex3f(Verticies[Triangles[i].v1].Pos.x, Verticies[Triangles[i].v1].Pos.y, Verticies[Triangles[i].v1].Pos.z);
            
            glNormal3f(Verticies[Triangles[i].v2].Normal.x, Verticies[Triangles[i].v2].Normal.y, Verticies[Triangles[i].v2].Normal.z);
            glVertex3f(Verticies[Triangles[i].v2].Pos.x, Verticies[Triangles[i].v2].Pos.y, Verticies[Triangles[i].v2].Pos.z);
            
            glNormal3f(Verticies[Triangles[i].v3].Normal.x, Verticies[Triangles[i].v3].Normal.y, Verticies[Triangles[i].v3].Normal.z);
            glVertex3f(Verticies[Triangles[i].v3].Pos.x, Verticies[Triangles[i].v3].Pos.
        }
glEnd(); //Stop drawing!

    }
}