/// <summary>
/// Calculate a path using the A* algorithm and the specified input.
/// </summary>
/// <param name="inInput">Input used to calculate path with.</param>
public override NavTilePath FindPath(FindPathInput inInput)
{
NavNodeHeap openSet = new NavNodeHeap();
HashSet <Vector2Int> closedSet = new HashSet <Vector2Int>();
PathfindingNode startNode = GetNode(inInput.StartCoordinate);
openSet.Add(startNode);
Vector2Int targetPosition = inInput.TargetCoordinate;
while (openSet.Count > 0)
{
PathfindingNode currentNode = openSet.RemoveFirst();
closedSet.Add(currentNode.Coordinate);
if (currentNode.Coordinate == targetPosition)
{
// Path found.
List <Vector2Int> pathInCoordinates = RetracePath(startNode, currentNode);
#if UNITY_EDITOR
NavTilePathVisualizer.SetDebugVisualization(inInput.Visualizer, closedSet.ToList(), openSet.GetCoordinateList(), pathInCoordinates);
#endif
return(ConvertCoordinatesToPath(pathInCoordinates, inInput.AreaMask));
}
foreach (Vector2Int neighbourCoordinate in GetWalkableNeighbours(currentNode, inInput.AreaMask, inInput.DiagonalAllowed, inInput.CutCorners))
{
if (inInput.PositionsToAvoid.Contains(neighbourCoordinate))
{
continue;
}
if (closedSet.Contains(neighbourCoordinate))
{
continue;
}
// Get node from the open set if it exists, otherwise, create one.
PathfindingNode neighbourNode = openSet.GetExistingNode(neighbourCoordinate) ?? GetNode(neighbourCoordinate);
int movementPenalty = inInput.IgnoreTileCost ? 0 : neighbourNode.TileCost;
int newMovementCostToNeighbour = currentNode.GCost + GetAdjacentCost(neighbourCoordinate - currentNode.Coordinate) + movementPenalty;
if (neighbourNode.GCost == 0 || newMovementCostToNeighbour < neighbourNode.GCost)
{
neighbourNode.GCost = newMovementCostToNeighbour;
neighbourNode.HCost = GetHeuristicCost(neighbourCoordinate, inInput.TargetCoordinate, inInput.DiagonalAllowed);
neighbourNode.ParentNode = currentNode;
if (openSet.Contains(neighbourNode))
{
openSet.UpdateItem(neighbourNode);
}
else
{
openSet.Add(neighbourNode);
}
}
}
}
// Path not found.
return(null);
}