struct Vector
{
  float *dim;

  Vector ()
  {
    dim = new float [3];
  }
};

struct Face
{
  float an_N, an_P;
  int P, N;
  Vector Af;
  float Ad;
  Vector cnt;
  float ifac;
  float mf;
};

std::vector <Face> face;

Face temp_face;

for (;;)
{
    temp_face.cnt.dim[0] = 0.f;
    temp_face.cnt.dim[1] = 0.f;
    temp_face.cnt.dim[2] = 0.f;

    for (int q=0; q<n_vtx_2D; ++q)
    {
        temp_face.cnt = temp_face.cnt + pt[vtx[q]] / n_vtx_2D;
    }

    face.push_back(temp_face);
}

std::cout << face[0].cnt.dim[0] << std::endl;

struct Vector
{
    float dim[3];
};