CrowdControl/Assets/Feel/MMTools/Tools/MMProcedural/MMGridGenerators/MMGridGeneratorRandomWalkAvoider.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace MoreMountains.Tools
{
	/// <summary>
	/// Generates a grid with a path carved by a drunkard walk algorithm that will avoid another grid's walls
	/// </summary>
	public class MMGridGeneratorRandomWalkAvoider : MMGridGenerator
	{
		/// <summary>
		/// Generates a grid with a path carved by a drunkard walk algorithm that will avoid another grid's walls
		/// </summary>
		/// <param name="width"></param>
		/// <param name="height"></param>
		/// <param name="seed"></param>
		/// <param name="fillPercentage"></param>
		/// <returns></returns>
		public static int[,] Generate(int width, int height, int seed,  int fillPercentage, Vector2Int startingPoint, int[,] obstacles, int obstacleDistance, int maxIterations)
		{
			int[,] grid = PrepareGrid(ref width, ref height);
			grid = MMGridGeneratorFull.Generate(width, height, true);
			System.Random random = new System.Random(seed);
            
			int requiredFillQuantity = ((width * height) * fillPercentage) / 100;
			int fillCounter = 0;

			int currentX = startingPoint.x;
			int currentY = startingPoint.y;
			grid[currentX, currentY] = 0;
			fillCounter++;

			int iterationsCount = 0;
            
			while ((fillCounter < requiredFillQuantity) && (iterationsCount < maxIterations))
			{
				int direction = random.Next(4); 

				switch (direction)
				{
					case 0: // up
						if ( ((currentY + 1) <= height) && !ObstacleAt(obstacles, currentX, currentY + obstacleDistance) )
						{
							currentY++;
							grid = Carve(grid, currentX, currentY, ref fillCounter);
						}
						break;
					case 1: // down 
						if ( ((currentY - 1) > 1) && !ObstacleAt(obstacles, currentX, currentY - obstacleDistance) )
						{ 
							currentY--;
							grid = Carve(grid, currentX, currentY, ref fillCounter);
						}
						break;
					case 2: // left
						if (((currentX - 1) > 1) && !ObstacleAt(obstacles, currentX - obstacleDistance, currentY ) )
						{
							currentX--;
							grid = Carve(grid, currentX, currentY, ref fillCounter);
						}
						break;
					case 3: // right
						if (((currentX + 1) <= width) && !ObstacleAt(obstacles, currentX + obstacleDistance, currentY) )
						{
							currentX++;
							grid = Carve(grid, currentX, currentY, ref fillCounter);
						}
						break;
				}
				iterationsCount++;
			}
			return grid; 
		}

		/// <summary>
		/// Returns true if an obstacle is found at the specified coordinates, false otherwise
		/// </summary>
		/// <param name="obstacles"></param>
		/// <param name="x"></param>
		/// <param name="y"></param>
		/// <returns></returns>
		private static bool ObstacleAt(int[,] obstacles, int x, int y)
		{
			return (MMGridGenerator.GetValueAtGridCoordinate(obstacles, x, y, 1) == 1);
		}

		/// <summary>
		/// 
		/// </summary>
		/// <param name="grid"></param>
		/// <param name="x"></param>
		/// <param name="y"></param>
		/// <param name="fillCounter"></param>
		/// <returns></returns>
		private static int[,] Carve(int[,] grid, int x, int y, ref int fillCounter)
		{
			if (GetValueAtGridCoordinate(grid, x, y, 0) == 1)
			{
				SetGridCoordinate(grid, x, y, 0);
				fillCounter++; 
			}
			return grid;
		}
	}
}