为什么这个循环是没完没了的？

Question

嗨，伙计们！

我想切换到UE4，现在正在尝试重复通过路点找路的功能，它在Unity中工作得很好，但在C ++中有问题。这个函数产生了一个无限循环，据我所知，openList不能为空。我的c ++知识不足以解决这个问题。我将很高兴得到任何帮助！

TArray<FVector> UWaypointsPathfinding::GetPath(UWaypoint* startNode, UWaypoint* goalNode)
{
    UWaypoint* beginNode = startNode;
    set<UWaypoint*> openList;
    vector<UWaypoint*> closedList;

    openList.insert(startNode);
    startNode->previous = nullptr;
    startNode->distance = 0;


    while (!openList.empty())
    {
        startNode = *openList.begin();
        openList.erase(openList.begin());


        float dist = startNode->distance;
        closedList.push_back(startNode);
        if(startNode == goalNode) break;

        int l = startNode->nearest.Num();
        for (int i = 0; i < l; i++)
        {
            UWaypoint* node = startNode->nearest[i]->FindComponentByClass<UWaypoint>();
            if(find(closedList.begin(),closedList.end(),node) != closedList.end() || openList.find(node) != openList.end())
                continue;

            node->previous = startNode;
            node->distance = dist + FVector::Dist(node->GetOwner()->GetActorLocation(), startNode->GetOwner()->GetActorLocation());
            node->distance += FVector::Dist(node->GetOwner()->GetActorLocation(), goalNode->GetOwner()->GetActorLocation());

            openList.insert(startNode);
        }


    }

    // create path...

    return TArray<FVector>();
}

据推测，问题出在这篇文章中

if(startNode == goalNode) break;

int l = startNode->nearest.Num();
for (int i = 0; i < l; i++)
{
   UWaypoint* node = startNode->nearest[i]->FindComponentByClass<UWaypoint>();
   if(find(closedList.begin(),closedList.end(),node) != closedList.end() || openList.find(node) != openList.end())
                        continue;

    node->previous = startNode;
    node->distance = dist + FVector::Dist(node->GetOwner()->GetActorLocation(), startNode->GetOwner()->GetActorLocation());
    node->distance += FVector::Dist(node->GetOwner()->GetActorLocation(), goalNode->GetOwner()->GetActorLocation());

    openList.insert(startNode);
}

Answer 1

逻辑很奇怪，所以这可能是一个错误的类型。在开始处将startNode插入到openList，然后在循环中擦除它并再次插入。因此，openList将始终具有单个成员startNode，并且所有周期都是相同的。也许您的意思是在循环的最后一行使用openList.insert(node);而不是openList.insert(startNode);？