private void GenerateIndices()
        {
            List <StaticVertex> tempVertices = new List <StaticVertex>();
            List <int>          tempIndices  = new List <int>();

            foreach (StaticVertex v in VertexData)
            {
                //verifica se esiste un vertice giĆ  nella lista
                int  i     = 0;
                bool found = false;
                foreach (StaticVertex v2 in tempVertices)
                {
                    if (StaticVertex.Compare(v, v2))
                    {
                        //travato
                        found = true;
                        break;
                    }
                    i++;
                }

                if (found)
                {
                    tempIndices.Add(i);
                    StaticVertex v2 = tempVertices[i];
                    //somma le normali
                }
                else
                {
                    i = tempVertices.Count;
                    tempVertices.Add(v);
                    tempIndices.Add(i);
                }

                //normali
                StaticVertex vTemp = tempVertices[i];
                vTemp.Normal   += v.Normal;
                tempVertices[i] = vTemp;
            }


            //normalizzazione finale
            VertexData.Clear();
            //foreach (VertexFormat v in tempVertices)
            //{
            //    v.Normal.Normalize();
            //    Vertices.Add(v);
            //}
            VertexData.AddRange(tempVertices);

            IndexData.Clear();
            IndexData.AddRange(tempIndices);
        }