/// <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;
}
}
}
/// <summary>
/// Returns an enumerator that creates a maze by linking cells using prim's algorithm
/// </summary>
/// <param name="service"></param>
/// <returns></returns>
public override IEnumerator CreateMazeRoutine(MazeGenerationService service)
{
//create data structures necessary for algorithm to work
MazeCell[] cells = service.Cells.Cast <MazeCell>().ToArray();
List <MazeCell> frontier = new List <MazeCell>();
//set starting point
MazeCell startCell = service.RootCell;
startCell.MarkAsVisited();
//add neighbours of starting cell to frontier
frontier.AddRange(service.GetNeighbours(startCell));
while (frontier.Count != 0)
{
//pick a random frontier cell, mark it as visited and remove it from the frontier
MazeCell randomFrontierCell = frontier[Random.Range(0, frontier.Count)];
randomFrontierCell.MarkAsVisited();
frontier.Remove(randomFrontierCell);
//pick a random visited neighbour of it and link it with it
List <MazeCell> visitedNeighbours = service.GetVisitedNeighbours(randomFrontierCell);
if (visitedNeighbours.Count > 0)
{
MazeCell randomVisitedNeighbour = visitedNeighbours[Random.Range(0, visitedNeighbours.Count)];
randomFrontierCell.CreatePassage(randomVisitedNeighbour);
randomVisitedNeighbour.CreatePassage(randomFrontierCell);
}
//add unvisited neighbours of it to the frontier if they aren't already in it
List <MazeCell> unvisitedNeighbours = service.GetUnVisitedNeighbours(randomFrontierCell);
foreach (MazeCell cell in unvisitedNeighbours)
{
if (!frontier.Contains(cell))
{
frontier.Add(cell);
}
}
randomFrontierCell.ShowAsStep(true);
yield return(null);
randomFrontierCell.ShowAsStep(false);
}
CompletedRoutine();
}
/// <summary>
/// Returns an enumerator that creates a maze by linking cells using the adlous broder algorithm
/// </summary>
/// <param name="service"></param>
/// <returns></returns>
public override IEnumerator CreateMazeRoutine(MazeGenerationService service)
{
//create data structures necessary for algorithm to work
List <MazeCell> visited = new List <MazeCell>();
//set starting point
MazeCell startCell = service.RootCell;
startCell.MarkAsVisited();
visited.Add(startCell);
//set current cel as starting cell
MazeCell currentCell = startCell;
//loop until all cells have been visited
long totalCells = service.Cells.LongLength;
while (visited.Count != totalCells)
{
//pick a random neighbour of the current cell
List <MazeCell> neighbours = service.GetNeighbours(currentCell);
MazeCell randomNeighbour = neighbours[Random.Range(0, neighbours.Count)];
if (!randomNeighbour.IsVisited)
{
//if the random neighbour hasn't been visited yet, mark it as visited
randomNeighbour.MarkAsVisited();
visited.Add(randomNeighbour);
//create passage between cell and neighbour
randomNeighbour.CreatePassage(currentCell);
currentCell.CreatePassage(randomNeighbour);
}
//set current cell to random neighbour to travel from it
currentCell = randomNeighbour;
//show stepping feedback
currentCell.ShowAsStep(true);
yield return(null);
currentCell.ShowAsStep(false);
}
CompletedRoutine();
}
