public static List <Tile> FindPath_BFS(TileGrid grid, Tile start, Tile end, List <IVisualStep> outSteps)
{
// Visual stuff
outSteps.Add(new MarkStartTileStep(start));
outSteps.Add(new MarkEndTileStep(end));
// ~Visual stuff
HashSet <Tile> visited = new HashSet <Tile>();
visited.Add(start);
Queue <Tile> frontier = new Queue <Tile>();
frontier.Enqueue(start);
start.PrevTile = null;
while (frontier.Count > 0)
{
Tile current = frontier.Dequeue();
// 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))
{
visited.Add(neighbor);
frontier.Enqueue(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);
}
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);
}
