/// <summary>
/// Executes a random walk from given unvisited cell adding visited cells to visited list on finish
/// </summary>
/// <param name="unvisitedCell"></param>
/// <param name="service"></param>
/// <param name="visited"></param>
private void RandomWalk(MazeCell unvisitedCell, MazeGenerationService service, List <MazeCell> visited)
{
//setup data structures necessary for the random walk to take place
List <KeyValuePair <MazeCell, Vector2Int> > records = new List <KeyValuePair <MazeCell, Vector2Int> >();
List <MazeCell> neighbours = service.GetNeighbours(unvisitedCell);
//pick a random neighbour as the walking position and check whether it is not already visited
MazeCell walker = neighbours[Random.Range(0, neighbours.Count)];
if (walker.IsVisited)
{
//mark the unvisited cell as visited
unvisitedCell.MarkAsVisited();
visited.Add(unvisitedCell);
//link unvisited cell to the walker and return
unvisitedCell.CreatePassage(walker);
walker.CreatePassage(unvisitedCell);
return;
}
//get the direction relative to the walker so we can store it as a record
Vector2Int direction = unvisitedCell.GetDirectionRelative(walker);
records.Add(new KeyValuePair <MazeCell, Vector2Int>(unvisitedCell, direction));
//loop until there are not records left
while (records.Count != 0)
{
//refresh the neighbours list with the walkers neighbours
neighbours.Clear();
neighbours.AddRange(service.GetNeighbours(walker));
//pick a random neighbour, and record the direction from the walker to it
MazeCell randomNeighbour = neighbours[Random.Range(0, neighbours.Count)];
direction = walker.GetDirectionRelative(randomNeighbour);
if (!records.TryUpdate(walker, direction))
{
records.Add(new KeyValuePair <MazeCell, Vector2Int>(walker, direction));
}
if (randomNeighbour.IsVisited)
{
//if the random neighbour is visited, carve out a path using the records and clear the records list
MarkRecordAsVisitedRecursive(records[0], records, service, visited);
records.Clear();
}
else
{
//if the random neighbour isn't visited yet, set it as the new walker cell
walker = randomNeighbour;
}
}
}
