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Added new options when end can't be reached #4

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Added new options when end can't be reached #4

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2 changes: 2 additions & 0 deletions AStar/Options/PathFinderOptions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@ public class PathFinderOptions

public int SearchLimit { get; set; }

public bool ClosestNodeWhenCantReach { get; set; }

public PathFinderOptions()
{
HeuristicFormula = HeuristicFormula.Manhattan;
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23 changes: 21 additions & 2 deletions AStar/PathFinder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,8 @@ public Position[] FindPath(Position start, Position end)
{
var nodesVisited = 0;
IModelAGraph<PathFinderNode> graph = new PathFinderGraph(_world.Height, _world.Width, _options.UseDiagonals);
var lowestNode = start;
var lowestNodeDist = int.MaxValue;

var startNode = new PathFinderNode(position: start, g: 0, h: 2, parentNodePosition: start);
graph.OpenNode(startNode);
Expand All @@ -62,6 +64,13 @@ public Position[] FindPath(Position start, Position end)
}

var newG = q.G + DistanceBetweenNodes;
var distanceBetweenSuccessorAndEnd = this.CalculateDistance(q.Position, end);

if (distanceBetweenSuccessorAndEnd < lowestNodeDist)
{
lowestNode = q.Position;
lowestNodeDist = distanceBetweenSuccessorAndEnd;
}

if (_options.PunishChangeDirection)
{
Expand All @@ -72,7 +81,7 @@ public Position[] FindPath(Position start, Position end)
{
if (qIsHorizontallyAdjacent)
{
newG += Math.Abs(successor.Position.Row - end.Row) + Math.Abs(successor.Position.Column - end.Column);
newG += this.CalculateDistance(successor.Position, end);
}
}

Expand All @@ -81,7 +90,7 @@ public Position[] FindPath(Position start, Position end)
{
if (!qIsHorizontallyAdjacent)
{
newG += Math.Abs(successor.Position.Row - end.Row) + Math.Abs(successor.Position.Column - end.Column);
newG += this.CalculateDistance(successor.Position, end);
}
}
}
Expand All @@ -101,9 +110,19 @@ public Position[] FindPath(Position start, Position end)
nodesVisited++;
}

if (_options.ClosestNodeWhenCantReach && lowestNode != start)
{
return this.FindPath(start, lowestNode);
}

return new Position[0];
}

private int CalculateDistance(Position currentNode, Position endNode)
{
return Math.Abs(currentNode.Row - endNode.Row) + Math.Abs(currentNode.Column - endNode.Column);
}

private bool BetterPathToSuccessorFound(PathFinderNode updateSuccessor, PathFinderNode currentSuccessor)
{
return !currentSuccessor.HasBeenVisited ||
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