/// <summary>
/// Get all the neighbors of a given tile in the grid.
/// </summary>
/// <param name="_node">Node to get neighbors for.</param>
/// <returns>List of node neighbors.</returns>
public List <Node> GetNeighbours(Node _node, ePathFindDistanceType _distanceType)
{
if (m_Neighbours.Count > 0)
{
m_Neighbours.Clear();
m_Neighbours = null;
}
m_Neighbours = new List <Node>();
int x = 0, y = 0;
switch (_distanceType)
{
case ePathFindDistanceType.Manhattan:
y = 0;
for (x = -1; x <= 1; ++x)
{
Vector3Int position = new Vector3Int(x, y, 0);
AddNodeNeighbour(position, _node);
}
x = 0;
for (y = -1; y <= 1; ++y)
{
Vector3Int position = new Vector3Int(x, y, 0);
AddNodeNeighbour(position, _node);
}
break;
case ePathFindDistanceType.Euclidean:
for (x = -1; x <= 1; x++)
{
for (y = -1; y <= 1; y++)
{
Vector3Int position = new Vector3Int(x, y, 0);
AddNodeNeighbour(position, _node);
}
}
break;
default:
break;
}
return(m_Neighbours);
}
/// <summary>
/// Find a path between two points.
/// </summary>
/// <param name="_grid">Grid to search.</param>
/// <param name="_startPos">Starting position.</param>
/// <param name="_targetPos">Ending position.</param>
/// <param name="_distance">The type of distance, Euclidean or Manhattan.</param>
/// <param name="_ignorePrices">If true, will ignore tile price (how much it "cost" to walk on).</param>
/// <returns>List of points that represent the path to walk.</returns>
public static HashSet <Vector3Int> FindPath(
Grid _grid, Vector3Int _startPos, Vector3Int _targetPos,
ePathFindDistanceType _distance = ePathFindDistanceType.Euclidean, bool _ignorePrices = false)
{
// find path
List <Node> nodes_path = _ImpFindPath(_grid, _startPos, _targetPos, _distance, _ignorePrices);
// convert to a list of points and return
HashSet <Vector3Int> ret = new HashSet <Vector3Int>();
if (nodes_path != null)
{
foreach (Node node in nodes_path)
{
ret.Add(node.m_GridPosition);
}
}
return(ret);
}
/// <summary>
/// Internal function that implements the path-finding algorithm.
/// </summary>
/// <param name="_grid">Grid to search.</param>
/// <param name="_startPos">Starting position.</param>
/// <param name="_targetPos">Ending position.</param>
/// <param name="_distance">The type of distance, Euclidean or Manhattan.</param>
/// <param name="_ignorePrices">If true, will ignore tile price (how much it "cost" to walk on).</param>
/// <returns>List of grid nodes that represent the path to walk.</returns>
private static List <Node> _ImpFindPath(Grid _grid, Vector3Int _startPos, Vector3Int _targetPos, ePathFindDistanceType _distance = ePathFindDistanceType.Euclidean, bool _ignorePrices = false)
{
Node startNode = _grid.m_NodesDic[_startPos];
Node targetNode = _grid.m_NodesDic[_targetPos];
List <Node> openSet = new List <Node>();
HashSet <Node> closedSet = new HashSet <Node>();
openSet.Add(startNode);
while (openSet.Count > 0)
{
Node currentNode = openSet[0];
//Debug.Log( "[currentNode] x = " + currentNode.gridX + " y = " + currentNode.gridY );
for (int i = 1; i < openSet.Count; i++)
{
if (openSet[i].fCost < currentNode.fCost || openSet[i].fCost == currentNode.fCost && openSet[i].m_hCost < currentNode.m_hCost)
{
currentNode = openSet[i];
}
}
openSet.Remove(currentNode);
closedSet.Add(currentNode);
if (currentNode.m_GridPosition == targetNode.m_GridPosition)
{
return(RetracePath(startNode, targetNode));
}
foreach (Node neighbour in _grid.GetNeighbours(currentNode, _distance))
{
if (!neighbour.m_Walkable || closedSet.Contains(neighbour))
{
continue;
}
int newMovementCostToNeighbour = currentNode.m_gCost + GetDistance(currentNode, neighbour) * (_ignorePrices ? 1 : (int)(10.0f * neighbour.m_Price));
if (newMovementCostToNeighbour < neighbour.m_gCost || !openSet.Contains(neighbour))
{
neighbour.m_gCost = newMovementCostToNeighbour;
neighbour.m_hCost = GetDistance(neighbour, targetNode);
neighbour.m_Parent = currentNode;
if (!openSet.Contains(neighbour))
{
openSet.Add(neighbour);
}
}
}
}
Debug.LogError("end of _ImpFindPath() return null");
return(null);
}
