public IEnumerator ComputePathAsync(IPathNode startNode, IPathNode endNode)
{
FindingParams findingParams = new FindingParams()
{
startNode = startNode,
endNode = endNode,
computedPath = new LinkedList <IPathNode>()
};
return(ComputePathCoroutine(findingParams));
}
public LinkedList <IPathNode> ComputePath(IPathNode startNode, IPathNode endNode)
{
FindingParams findingParams = new FindingParams()
{
startNode = startNode,
endNode = endNode,
computedPath = new LinkedList <IPathNode>()
};
IEnumerator coroutine = ComputePathCoroutine(findingParams);
while (coroutine.MoveNext())
{
;
}
return(findingParams.computedPath);
}
public IEnumerator ComputePathCoroutine(FindingParams findingParams)
{
//NOTE: curTicks will be different for each call.
// if openTicks == curTicks, it means the node in in openList, same for closeList and closeTicks.
// this is faster than reset a bool isInOpenList for all nodes before next call to this method
int curTicks = (int)(Time.realtimeSinceStartup * 1000);
IsComputing = true;
if (findingParams.startNode == findingParams.endNode)
{
findingParams.computedPath.AddLast(findingParams.startNode);
}
else
{
//1) Add the starting square (or node) to the open list.
m_closeList.Clear();
m_openList.Clear();
m_openList.AddLast(findingParams.startNode); findingParams.startNode.openTicks = curTicks;
//2) Repeat the following:
LinkedListNode <IPathNode> curNode;
int iterations = 0;
int iterChunkCounter = k_IterationsPerProcessChunk;
do
{
++iterations;
--iterChunkCounter;
if (iterChunkCounter == 0)
{
iterChunkCounter = k_IterationsPerProcessChunk;
yield return(null);
}
//a) Look for the lowest F cost square on the open list. We refer to this as the current square.
//curNode = m_vOpen.First(c => c.Score == m_vOpen.Min(c2 => c2.Score));
curNode = null;
for (LinkedListNode <IPathNode> pathNode = m_openList.First; pathNode != null; pathNode = pathNode.Next)
{
if (curNode == null || pathNode.Value.Score < curNode.Value.Score)
{
curNode = pathNode;
}
}
//b) Switch it to the closed list.
m_openList.Remove(curNode); curNode.Value.openTicks = 0;
m_closeList.AddLast(curNode); curNode.Value.closeTicks = curTicks;
//c) For each of the 8 squares adjacent to this current square …
for (int i = 0; i < curNode.Value.GetNeighborCount(); ++i)
{
//If it is not walkable or if it is on the closed list, ignore it. Otherwise do the following.
IPathNode neigborNode = curNode.Value.GetNeighbor(i);
float movingCost = curNode.Value.GetNeigborMovingCost(i);
if (
neigborNode.closeTicks != curTicks && // if closeList does not contains node
movingCost != k_InfiniteCostValue && neigborNode.IsPassable()
)
{
//If it isn’t on the open list, add it to the open list. Make the current square the parent of this square. Record the F, G, and H costs of the square.
float newCost = curNode.Value.Cost + movingCost;
if (neigborNode.openTicks != curTicks) // if openList does not contains node
{
m_openList.AddLast(neigborNode); neigborNode.openTicks = curTicks;
neigborNode.ParentNode = curNode.Value;
neigborNode.Cost = newCost;
neigborNode.Score = neigborNode.Cost + neigborNode.GetHeuristic();
if (neigborNode == findingParams.endNode)
{
curNode.Value = neigborNode;
m_openList.Clear(); // force to exit while
break;
}
}
//If it is on the open list already, check to see if this path to that square is better, using G cost as the measure. A lower G cost means that this is a better path.
else if (newCost < neigborNode.Cost)
{
//If so, change the parent of the square to the current square, and recalculate the G and F scores of the square.
neigborNode.ParentNode = curNode.Value;
neigborNode.Cost = newCost;
neigborNode.Score = neigborNode.Cost + neigborNode.GetHeuristic();
}
}
}
}while (m_openList.Count > 0 && (MaxIterations <= 0 || iterations < MaxIterations));
//Debug.Log("iterations: " + iterations);
//d) Stop when you:
//Add the target square to the closed list, in which case the path has been found (see note below), or
//Fail to find the target square, and the open list is empty. In this case, there is no path.
if (curNode.Value == findingParams.endNode)
{
//3) Save the path. Working backwards from the target square, go from each square to its parent square until you reach the starting square. That is your path.
findingParams.computedPath.AddLast(curNode.Value);
do
{
curNode.Value = curNode.Value.ParentNode;
findingParams.computedPath.AddLast(curNode.Value);
}while (curNode.Value != findingParams.startNode);
}
}
IsComputing = false;
yield return(findingParams);
}