Visualizing normals and tangents using GL_LINES?

[HiredK]

What would be the best way to display this:

[IMG]http://www.fabiensanglard.net/bumpMapping/normalVis.jpg[/IMG]

I tried looking on Google but It's not explained anywhere, here's my object.h if that can help

#ifndef OBJECT_H_
    #define OBJECT_H_

#include "MaterialsLibrary.h"
#include "Common.h"
#include "Vertex.h"

class Object {
    public:
        struct Polygon {
            short a;
            short b;
            short c;
        };

        struct MapCoord {
            float u;
            float v;
        };

         Object();
        ~Object();

        int vertices_qty;
        int polygons_qty;

        Material* material;

        map<int,Vertex> vertex;
        map<int,Vertex> normal;
        map<int,Vertex> tangent;
        map<int,Vertex> bitangent;
        map<int,Polygon> polygon;
        map<int,MapCoord> mapcoord;

        void load();

    private:
        void generateNormalsAndTangents();
};

#endif

[Jallen]

Surely you can just loop through the vertecies, specifying first the vertex itself, then the vertex's position + its normal (you may want to multiply the normal by a scalar first so the line isn't tiny) with GL_LINES as the drawing type.

I'm no GL expert but something like

glBegin(GL_LINE);
for(int i = 0; i < vertexContainerSize; i++)
{
    Vertex endpoint = vert[i] + (5 * norm[i]);
    glVertex3f(vert[i].x, vert[i].y, vert[i].z);
    glVertex3f(endpoint[i].x, endpoint[i].y, endpoint[i].z);
}
glEnd();

You should easily be able to work out how to do tangents too.

Surely it's as simple as that?

[b]Edit:[/b]
Just saw you've already sort of done it in waywo