I have found very difficult to calculate face normals for the lessons heightmap loading part , I calculated something like this for(int nIndex=0;nIndex<m_nVertexCount;nIndex+=3) { CVec v1=m_pVertices[nIndex+2]-m_pVertices[nIndex]; CVec v2=m_pVertices[nIndex+1]-m_pVertices[nIndex]; CVec n=Cross(v1,v2); m_pNormals[nIndex]=Normalize(n); } hm.... come to think more of it I think I found what the problem is