``` private void AddTop(int x, int y, int z, List<float> verts, List<uint> indices) { ui

 private void AddTop(int x, int y, int z, List<float> verts, List<uint> indices)
    {

      uint oldCount = (uint)verts.Count;

      var toAdd = new float[] {
        //X          Y         Z          U   V
          x + 0.5f,  y + 0.5f, z + -0.5f, 1f, 1f,
          x + 0.5f,  y + 0.5f, z +  0.5f, 1f, 0f,
          x + -0.5f, y + 0.5f, z +  0.5f, 0f, 0f,
          x + -0.5f, y + 0.5f, z + -0.5f, 0f, 1f
      };


      verts.AddRange(toAdd);

      indices.AddRange(Indices.Select(x => x + oldCount));

    }