source: GTP/trunk/Lib/Vis/Preprocessing/manual/code/pseudocode.cpp @ 2066

//---- initialisation
Stack.Push(kDTree.Root);
//---- while there are some nodes in the stack or the query queue
while (!Stack.Empty() $||$ !QueryQueue.Empty()) {
  //---- PART 1: processing finished occlusion queries
  while (!QueryQueue.Empty() &&
         (ResultAvailable(QueryQueue.Front()) $||$ Stack.Empty())) {
    if (!ResultAvailable(QueryQueue.Front())) {
      //--- result is not available and the stack is empty
      //--- check if we can do some conservative decision
      N = QueryQueue.GetLeastCostNode();
      if (N.renderingCost < MaxRenderCost) {
        RenderSubtree(N);
        QueryQueue.DequeLeastCostNode();
        //-- we do not change N's visibility classfication -
        //-- N remains in the cut for the next frame
      } else
        //-- wait for the availability of the result
        while (!QueryQueue.ResultAvailable) Wait();
    } else {
      N = QueryQueue.Dequeue();
      //-- check the result of the query
      if ( N.visiblePixels $>$ VisibilityThreshold )  {
        N.visibility = VISIBLE;
        if (IsLeaf(N))
          Render(N);
        else {
          //-- pull down
          Stack.Push(FarChild(N)); Stack.Push(CloseChild(N));
        }
      } else {
        N.visibility = INVISIBLE;
        //-- pull up
        PullUpInvisibility(N);
      }
    }
  }
  
  //---- PART 2: kd-tree traversal
  if (!Stack.Empty()) {
    N = Stack.Pop();
    N.lastVisited = frameID;
    if (InsideViewFrustum(N)) {
      //-- skip testing of all nodes above the cut
      if (!IsAboveTheCut(N)) {
        IssueOcclustionQuery(N); QueryQueue.Enqueue(N);
        if (WasVisible(N) $&&$ IsLeaf(N))
          Render(N);
        else {
          //-- go down the kD-tree
          Stack.Push(FarChild(N)); Stack.Push(CloseChild(N)); 
        }
      }
    }
  }
}