Bad lighting behaviour (fixed pipeline) - opengl

Question

I'm trying to render an object (say cube) with OpenGL 1.1 (I know that doesn't makes sense nowadays, but I've to use this). Everything works fine until I try some lighting.
Here's the problem:
The Global variable set are:
static GLfloat light_position[] = {1.0, 1.0, 2*cZ.x , 0.0};
// cZ.x is the minimum z of the mesh. I know
// this is at infinity, but don't work also with w=1.0
In the main function:
...
glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity(); // Reset The Modelview Matrix
glEnable(GL_LIGHT0);
glEnable(GL_LIGHTING);
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
....
Drawing a mesh k
// While drawing mesh k
GLfloat light_ambient[] = {COLOUR[k][0], COLOUR[k][1], COLOUR[k][2], 1.0};
GLfloat light_diffuse[] = {COLOUR[k][0], COLOUR[k][1], COLOUR[k][2], 1.0};
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);
....
//This is a mesh, so will be drawn using triangles
glBegin(GL_TRIANGLES);
//Triangles will be defined by vertex indices in faces
for (unsigned int i = 0; i<mesh->faces.size(); i++){
int index1 = mesh->faces.at(i).x;
int index2 = mesh->faces.at(i).y;
int index3 = mesh->faces.at(i).z;
glNormal3f(mesh->normals.at(i).x,mesh->normals.at(i).y,mesh->normals.at(i).z);
glVertex3f(mesh->vertices.at(index1).x, mesh->vertices.at(index1).y, mesh->vertices.at(index1).z);
glVertex3f(mesh->vertices.at(index2).x, mesh->vertices.at(index2).y, mesh->vertices.at(index2).z);
glVertex3f(mesh->vertices.at(index3).x, mesh->vertices.at(index3).y, mesh->vertices.at(index3).z);
}
glEnd();
....
Whereas the normal are computed as:
glm::vec3 currFace = m->faces.at(faceIndex);
glm::vec3 vert1 = m->vertices.at(currFace.x);
glm::vec3 vert2 = m->vertices.at(currFace.y);
glm::vec3 vert3 = m->vertices.at(currFace.z);
glm::vec3 side1 = (vert2 - vert1);
glm::vec3 side2 = (vert3 - vert1);
glm::vec3 normal = glm::cross(side1, side2);
normal = glm::normalize(normal);
I'm really struggling to understand what's wrong, can you point me in the right direction?
EDIT: This happens similarly with the standford bunny (taken from standford repo, so it's well formed)
http://imgur.com/Z6225QG

Answer 1

Looking at your normals picture it looks like that more than not being shaded, some of your object faces are transparent.
I used to have a similar problem while learning OpenGL, in my case I forgot to enable DEPTH_TEST. You can do it simply adding this line to your GL init function function:
glEnable(GL_DEPTH_TEST);
Give it a try