Pathfinding.cs

using System.Collections.Generic;

namespace ProcGenTiles
{
	public class Pathfinding
	{
		HashSet<(int x, int y)> visited = new HashSet<(int x, int y)>();
		Queue<(int x, int y)> queue = new Queue<(int x, int y)>();
		Map Map;

		public Pathfinding(Map map)
		{
			Map = map;
		}

		public void LandWaterFloodfill((int x, int y) start)
		{
			queue.Clear();
			queue.Enqueue(start);
			visited.Clear();
			visited.Add(start);

			while (queue.Count > 0)
			{
				(int x, int y) coords = queue.Dequeue();
				Tile tile = Map.GetTile(coords); //Can always assume value is not null due to AddNeighborsToQueue

				//Check the elevation layer, if it doesn't exist exit with an error
				if (!tile.ValuesHere.ContainsKey("Elevation"))
				{
					throw new InvalidOperationException("Cannot floodfill without elevation data");
				}

				if (tile.ValuesHere["Elevation"] >= 0)
					tile.ValuesHere.Add("Land", 1); //Heck this only takes floats so we'll use positive 1 for true and 0 for false
				else
					tile.ValuesHere.Add("Land", 0);
				
				AddFourNeighbors(coords.x, coords.y, queue);
			}
		}
		
		public void MarkAllRegions()
		{
			//Get a list of all tiles
			List<(int x, int y)> values = new List<(int x, int y)>();
			for (int x = 0; x < Map.Width; x++)
			{
				for (int y = 0; y < Map.Height; y++)
				{
					values.Add((x, y));
				}
			}
			//Move first tile from list to frontier
			Queue<(int x, int y)> frontier = new Queue<(int x, int y)>();
			visited.Clear();
			int region = 0; //Track which region we're marking
			//Add neighbors to frontier if Land values match
			
			while (values.Count > 0)
			{ //Loop for all tiles
				frontier.Enqueue(values[0]);
				visited.Add(values[0]);
				Tile compare = Map.GetTile(values[0]); //For checking the Land value
				
				while (frontier.Count > 0)
				{
					(int x, int y) coords = frontier.Dequeue();
					Tile found = Map.GetTile(coords);
					if (found.ValuesHere["Land"] == compare.ValuesHere["Land"])
					{ //The neighbor matches the start value so assign them the same region
						found.ValuesHere.TryAdd("Region", region);
						values.Remove(coords); //Delete from values if region is marked
						AddFourNeighbors(coords.x, coords.y, frontier);
					}
				}
				region++; //On to the next one if the frontier ran out
				visited.Clear();
			}
			//Mark until frontier is empty, removing values from the list
			//increment region and pop first item from list until list is empty
		}

		public void BFS((int x, int y) start)
		{

			visited.Add(start);
			queue.Enqueue(start);

			while (queue.Count > 0)
			{
				var current = queue.Dequeue();

				// Add neighboring tiles to the queue if not visited for 4 dir pathfinding: diamonds
				AddFourNeighbors(current.x, current.y, queue);

				//Thinking about running a Func<> through the params to determine what to do with the found tiles

			}
		}

		private void AddFourNeighbors(int x, int y, Queue<(int x, int y)> q)
		{
			AddNeighborToQueue(x - 1, y, q);
			AddNeighborToQueue(x + 1, y, q);
			AddNeighborToQueue(x, y - 1, q);
			AddNeighborToQueue(x, y + 1, q);
		}
		
		private void AddEightNeighbors(int x, int y, Queue<(int x, int y)> q)
		{ //Stubbed just in case
			AddFourNeighbors(x, y, q);
			AddNeighborToQueue(x - 1, y - 1, q);
			AddNeighborToQueue(x + 1, y - 1, q);
			AddNeighborToQueue(x - 1, y + 1, q);
			AddNeighborToQueue(x + 1, y + 1, q);
		}

		private void AddNeighborToQueue(int x, int y, Queue<(int x, int y)> q)
		{
			if (Map.IsValidTilePosition(x, y) && !visited.Contains((x, y)))
				q.Enqueue((x, y));
				visited.Add((x, y));
		}
	}
}