public Entities.Path FindPath(Entities.Grid grid, Entities.GridLocation startPoint, Entities.GridLocation endPoint)
{
var result = new ShortestPath.Optimization.Entities.Path();
var currentLocation = result.Add(grid[startPoint.X, startPoint.Y]);
currentLocation.DistanceFromStart = 0;
while (!IsCurrentLocationTheEndPoint(currentLocation, endPoint))
{
var moveX = _random.Next(3) - 1;
var moveY = _random.Next(3) - 1;
if (moveX != 0 || moveY != 0)
{
var newX = currentLocation.X + moveX;
var newY = currentLocation.Y + moveY;
if (grid.LocationIsTraversable(newX, newY))
{
var newLocation = grid[newX, newY];
newLocation.DistanceFromStart = currentLocation.DistanceFromStart + 1;
currentLocation = result.Add(newLocation);
}
}
}
return(result);
}
public Entities.Path FindPath(Entities.Grid grid, Entities.GridLocation startPoint, Entities.GridLocation endPoint)
{
var startingLocation = grid[startPoint.X, startPoint.Y];
var endingLocation = grid[endPoint.X, endPoint.Y];
ProcessLocation(0, grid, startingLocation, endingLocation);
return(RetraceSteps(grid, endPoint));
}
private Entities.Path RetraceSteps(Entities.Grid grid, Entities.GridLocation endPoint)
{
var resultPath = new Entities.Path();
var currentLocation = grid[endPoint.X, endPoint.Y];
resultPath.Add(currentLocation);
var pathLength = currentLocation.DistanceFromStart.Value;
for (int i = pathLength - 1; i >= 0; i--)
{
currentLocation = grid.LocationsAtDistance(i).SurroundingLocation(currentLocation).First();
resultPath.Add(currentLocation);
}
return(resultPath.Reverse());
}
private void ProcessLocation(int currentDistance, Entities.Grid grid, Entities.GridLocation startPoint, Entities.GridLocation endPoint)
{
var currentPoint = startPoint;
if (!currentPoint.DistanceFromStart.HasValue ||
currentPoint.DistanceFromStart.Value > currentDistance)
{
currentPoint.DistanceFromStart = currentDistance;
for (int xDelta = -1; xDelta < 2; xDelta++)
{
for (int yDelta = -1; yDelta < 2; yDelta++)
{
var newLocation = grid.TraversableLocationAtOffset(currentPoint, xDelta, yDelta);
if (newLocation != null)
{
ProcessLocation(currentDistance + 1, grid, newLocation, endPoint);
}
}
}
}
}
public static IEnumerable <Entities.GridLocation> SurroundingLocation(this IEnumerable <Entities.GridLocation> locations, Entities.GridLocation centerPoint)
{
var minX = centerPoint.X - 1;
var maxX = centerPoint.X + 1;
var minY = centerPoint.Y - 1;
var maxY = centerPoint.Y + 1;
return(locations.Where(l => l.X >= minX && l.X <= maxX && l.Y >= minY && l.Y <= maxY));
}
private static bool IsCurrentLocationTheEndPoint(Entities.GridLocation currentLocation, Entities.GridLocation endPoint)
{
return((currentLocation.X == endPoint.X) && (currentLocation.Y == endPoint.Y));
}
