private void buildLines(){
  while (!nodeEdgeStack.empty()) {
    HalfEdge e=(HalfEdge)nodeEdgeStack.pop();
    if (MarkHalfEdge.isMarked(e))     continue;
    buildLine(e);
  }
}

private void buildLines ( ) { while ( ! nodeEdgeStack . empty ( ) ) { HalfEdge e = ( HalfEdge ) nodeEdgeStack . pop ( ) ; if ( MarkHalfEdge . isMarked ( e ) ) continue ; buildLine ( e ) ; } }
for each edge in stack ( which must originate at a node ) extracts the line it initiates .
