public static List <Tile> FindPath_GreedyBestFirstSearch(TileGrid grid, Tile start, Tile end, List <IVisualStep> outSteps)
{
// Visual stuff
outSteps.Add(new MarkStartTileStep(start));
outSteps.Add(new MarkEndTileStep(end));
// ~Visual stuff
Comparison <Tile> heuristicComparison = (lhs, rhs) =>
{
float lhsCost = GetEuclideanHeuristicCost(lhs, end);
float rhsCost = GetEuclideanHeuristicCost(rhs, end);
return(lhsCost.CompareTo(rhsCost));
};
MinHeap <Tile> frontier = new MinHeap <Tile>(heuristicComparison);
frontier.Add(start);
HashSet <Tile> visited = new HashSet <Tile>();
visited.Add(start);
start.PrevTile = null;
while (frontier.Count > 0)
{
Tile current = frontier.Remove();
// Visual stuff
if (current != start && current != end)
{
outSteps.Add(new VisitTileStep(current));
}
// ~Visual stuff
if (current == end)
{
break;
}
foreach (var neighbor in grid.GetNeighbors(current))
{
if (!visited.Contains(neighbor))
{
frontier.Add(neighbor);
visited.Add(neighbor);
neighbor.PrevTile = current;
// Visual stuff
if (neighbor != end)
{
outSteps.Add(new PushTileInFrontierStep(neighbor, 0));
}
// ~Visual stuff
}
}
}
List <Tile> path = BacktrackToPath(end);
// Visual stuff
foreach (var tile in path)
{
if (tile == start || tile == end)
{
continue;
}
outSteps.Add(new MarkPathTileStep(tile));
}
// ~Visual stuff
return(path);
}
public static List <Tile> FindPath_Dijkstra(TileGrid grid, Tile start, Tile end, List <IVisualStep> outSteps)
{
// Visual stuff
outSteps.Add(new MarkStartTileStep(start));
outSteps.Add(new MarkEndTileStep(end));
// ~Visual stuff
foreach (var tile in grid.Tiles)
{
tile.Cost = int.MaxValue;
}
start.Cost = 0;
HashSet <Tile> visited = new HashSet <Tile>();
visited.Add(start);
MinHeap <Tile> frontier = new MinHeap <Tile>((lhs, rhs) => lhs.Cost.CompareTo(rhs.Cost));
frontier.Add(start);
start.PrevTile = null;
while (frontier.Count > 0)
{
Tile current = frontier.Remove();
// Visual stuff
if (current != start && current != end)
{
outSteps.Add(new VisitTileStep(current));
}
// ~Visual stuff
if (current == end)
{
break;
}
foreach (var neighbor in grid.GetNeighbors(current))
{
int newNeighborCost = current.Cost + neighbor.Weight;
if (newNeighborCost < neighbor.Cost)
{
neighbor.Cost = newNeighborCost;
neighbor.PrevTile = current;
}
if (!visited.Contains(neighbor))
{
visited.Add(neighbor);
frontier.Add(neighbor);
// Visual stuff
if (neighbor != end)
{
outSteps.Add(new PushTileInFrontierStep(neighbor, neighbor.Cost));
}
// ~Visual stuff
}
}
}
List <Tile> path = BacktrackToPath(end);
// Visual stuff
foreach (var tile in path)
{
if (tile == start || tile == end)
{
continue;
}
outSteps.Add(new MarkPathTileStep(tile));
}
// ~Visual stuff
return(path);
}
private static BreadCrumb FindPathReversed(Grid world, Point start, Point end)
{
var openList = new MinHeap <BreadCrumb>(256);
var brWorld = new BreadCrumb[world.Right, world.Top];
var current = new BreadCrumb(start)
{
Cost = 0
};
var finish = new BreadCrumb(end);
brWorld[current.Position.X, current.Position.Y] = current;
openList.Add(current);
while (openList.Count > 0)
{
//Find best item and switch it to the 'closedList'
current = openList.ExtractFirst();
current.OnClosedList = true;
//Find neighbours
for (var i = 0; i < Surrounding.Length; i++)
{
var tmp = new Point(current.Position.X + Surrounding[i].X, current.Position.Y + Surrounding[i].Y);
if (!world.ConnectionIsValid(current.Position, tmp))
{
continue;
}
try
{
//Check if we've already examined a neighbour, if not create a new node for it.
BreadCrumb node;
if (brWorld[tmp.X, tmp.Y] == null)
{
node = new BreadCrumb(tmp);
brWorld[tmp.X, tmp.Y] = node;
}
else
{
node = brWorld[tmp.X, tmp.Y];
}
//If the node is not on the 'closedList' check it's new score, keep the best
if (!node.OnClosedList)
{
var diff = 0;
if (current.Position.X != node.Position.X)
{
diff += 1;
}
if (current.Position.Y != node.Position.Y)
{
diff += 1;
}
var distance =
(int)Mathf.Pow(
Mathf.Max(Mathf.Abs(end.X - node.Position.X), Mathf.Abs(end.Y - node.Position.Y)), 2);
var cost = current.Cost + diff + distance;
if (cost < node.Cost)
{
node.Cost = cost;
node.Next = current;
}
//If the node wasn't on the openList yet, add it
if (!node.OnOpenList)
{
//Check to see if we're done
if (node.Equals(finish))
{
node.Next = current;
return(node);
}
node.OnOpenList = true;
openList.Add(node);
}
}
}
catch (Exception e)
{
Debug.LogWarning(tmp);
}
}
}
return(null); //no path found
}
