private void BuildVertexToHalfFacet(int vKey, int elementID, int halfFacetID)
        {
            ITopologicVertex v = GetVertexWithKey(vKey);

            if (v.V2HF == 0)
            {
                v.SetV2HF(elementID, halfFacetID);
                SetVertex(vKey, v);
            }

            if (_elements[elementID].GetSiblingHalfFacet(halfFacetID) == 0)
            {
                if (v.GetElementID() != elementID || v.GetHalfFacetID() != halfFacetID)
                {
                    v.SetV2HF(elementID, halfFacetID);
                    SetVertex(vKey, v);
                }
            }
        }