OBJ Model Renderering Gaps

Question

When I render a OBJ Wavefront model which I parse using a parser that I built myself, I get the following result when rendering:

Are the gaps that are present normal or is it just from faulty rendering code?

Here is the rendering code:

glPushMatrix();
glColor3f(1.0f, 1.0f, 1.0f);
glScaled(scale, scale, scale);

glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);

for (int i = 0; i < vertices_indexes.size()-3; i+=3) {
    glBegin(GL_TRIANGLE_FAN);
        if (is_normals) glNormal3f(normals.at(normals_indexes[i]).x, normals.at(normals_indexes[i]).y, normals.at(normals_indexes[i]).z);
        glVertex3f(vertices.at(vertices_indexes[i]).x, vertices.at(vertices_indexes[i]).y, vertices.at(vertices_indexes[i]).z);

        if (is_normals) glNormal3f(normals.at(normals_indexes[i+1]).x, normals.at(normals_indexes[i+1]).y, normals.at(normals_indexes[i+1]).z);
        glVertex3f(vertices.at(vertices_indexes[i + 1]).x, vertices.at(vertices_indexes[i + 1]).y, vertices.at(vertices_indexes[i + 1]).z);

        if (is_normals) glNormal3f(normals.at(normals_indexes[i+2]).x, normals.at(normals_indexes[i+2]).y, normals.at(normals_indexes[i+2]).z);
        glVertex3f(vertices.at(vertices_indexes[i + 2]).x, vertices.at(vertices_indexes[i + 2]).y, vertices.at(vertices_indexes[i + 2]).z);
    glEnd();
}

glPopMatrix();

Answer 1

Have you checked that your model is created with triangles and not quads? Most models you find will come rendered in quads by default, so you can either load it up in a 3D program (like Blender or Maya) and convert the mesh to triangles (Ctrl+T in Blender), or change your parser to handle quads.