/// <summary>
/// This is the A* function. This will be called multiple times until
/// the path is calculated. All the states values are storred in Ticket.
/// To calcualte the path this function must be called multiple times until
/// will return true!
/// </summary>
/// <param name="ticket">the request</param>
/// <param name="token">the cancelation token</param>
/// <returns>true if the processing finished.</returns>
private bool ProcessTicket(Ticket ticket, CancellationToken token)
{
/// Check the cancelation token.
if (token.IsCancellationRequested)
{
/// In case the Cancel was requested from external,
/// the function will return.
ticket.State = Ticket.STATE.CANCELLED;
token.ThrowIfCancellationRequested();
}
/// Switch the state to Processing.
ticket.State = Ticket.STATE.PROCESSING;
ticket.Steps++;
if (NavMesh.GetNodeType(ticket.GoalIndex) == NodeType.INVALID)
{
ticket.State = Ticket.STATE.INVALID_GOAL;
return(true);
}
/// Chekc if the StartIndex is the same with GoalIndex
if (ticket.StartIndex == ticket.GoalIndex)
{
ticket.Path.Add(ticket.StartIndex);
/// Search is stopped because the goal si the same with start node
ticket.State = Ticket.STATE.COMPLETED;
return(true);
}
/// This is the first step -> closed list is empty.
/// Add the start node to the closed list.
if (ticket.ClosedList.Count == 0)
{
Node startNode = new Node(ticket.StartIndex);
/// calculate the distance to target
startNode.DistanceToTarget = NavMesh.ComputeDistanceToGoal(ticket.GoalIndex, ticket.StartIndex);
/// Calculate the "F" value
startNode.F = startNode.DistanceToTarget;
/// Add the start node to the open list
ticket.OpenList[ticket.StartIndex] = startNode;
/// Set the current node to be the start node
ticket.CurrentNode = startNode;
}
//Console.WriteLine(this.GetType().FullName + ".ProcessTicket ticket.CurrentNode.Index=" + ticket.CurrentNode.Index);
/// If the start node does not have valid neighbors, try to GetNeighbors and add them to the open list
if (ticket.CurrentNode.Neighbors.Count == 0)
{
ticket.CurrentNode.Neighbors = NavMesh.GetNeighbors(ticket.CurrentNode.Index); // ticket->m_current->GetNeighbors();
}
foreach (ulong neighborIndex in ticket.CurrentNode.Neighbors)
{
/// Check if the goal is one of the neighbors
if (ticket.GoalIndex == neighborIndex)
{
ticket.Path.Add(ticket.GoalIndex);
Node node = ticket.CurrentNode;
do
{
ticket.Path.Add(node.Index);
//std::cout << "result " << node << " " << node->m_index << " " << node->m_f << std::endl;
node = node.Parent;
}while (node != null);
ticket.State = Ticket.STATE.COMPLETED;
return(true);
}
bool addedAlready = false;
Node neighborNode = null;
/// check if is in open list
if (ticket.OpenList.ContainsKey(neighborIndex))
{
addedAlready = true;
neighborNode = ticket.OpenList[neighborIndex];
}
else if (ticket.ClosedList.ContainsKey(neighborIndex))
{
addedAlready = true;
neighborNode = ticket.ClosedList[neighborIndex];
}
if (!addedAlready)
{
neighborNode = new Node(neighborIndex);
neighborNode.Parent = ticket.CurrentNode;
}
/// calculate the distance to target
neighborNode.DistanceToTarget = NavMesh.ComputeDistanceToGoal(ticket.GoalIndex, neighborIndex);
/// calculate the cost to travel from startIndex node to the neighbor note
neighborNode.Cost = NavMesh.ComputeCostToNeighbor(neighborIndex, ticket.CurrentNode.Index);
/// Calculate the "F" value
double _f = neighborNode.DistanceToTarget + neighborNode.Cost;
if (!addedAlready)
{
neighborNode.F = _f;
/// Add the neighbor node to the open list
ticket.OpenList[neighborIndex] = neighborNode;
}
else if (neighborNode.F > _f)
{
neighborNode.F = _f;
}
}
/// Chekc if there are some nodes in Open list
if (ticket.OpenList.Count == 0)
{
Node node = ticket.CurrentNode;
do
{
ticket.Path.Add(node.Index);
node = node.Parent;
}while (node != null);
/// If no nodes -> search is stopped due to no path to goal.
ticket.State = Ticket.STATE.STOPPED;
return(true);
}
/// Get the object with the minimal "F"
double f = Double.MaxValue;
foreach (ulong index in ticket.OpenList.Keys)
{
if (ticket.OpenList[index].F < f)
{
f = ticket.OpenList[index].F;
ticket.CurrentNode = ticket.OpenList[index];
}
}
ticket.OpenList.Remove(ticket.CurrentNode.Index);
ticket.ClosedList[ticket.CurrentNode.Index] = ticket.CurrentNode;
return(false);
}
