public void Reset()     //寻路开始时清空成本和指向
 {
     _state       = AStarEightDirectionsNodeState.unopened;
     _nextNode    = null;
     _startToCost = 0;
     _toEndCost   = 0;
     _totalCost   = 0;
 }
 public void Open(AStarEightDirectionsHeapNode nextNode, Vector2 destination)
 {
     _state    = AStarEightDirectionsNodeState.opened;
     _nextNode = nextNode;
     ComputeCost(destination);
 }
 public void Open(Vector2 destination)
 {
     _state = AStarEightDirectionsNodeState.opened;
     ComputeCost(destination);
 }
 public void Close()
 {
     _state = AStarEightDirectionsNodeState.closed;
 }