【p5.js】壁伸ばし法で迷路を生成する

迷路の幅と高さをそれぞれ width, height として設定し、
その数値にしたがって壁伸ばし法で迷路を生成する。
※迷路の幅と高さは5以上の奇数とする。

let maze1;

function setup() {
  maze1 = new Maze(15, 15);
  maze1.set_maze_kabenobashi();
  maze1.print_maze();
}

class Maze {
  constructor(width, height, seed=0) {
    this.PATH = 0;
    this.WALL = 1;
    this.width = width;
    this.height = height;
    if (this.width < 5 || this.height < 5) {
      return;
    }
    if (this.width%2 == 0) {
      this.width++;
    }
    if (this.height%2 == 0) {
      this.height++;
    }
    this.maze = Array.from(new Array(this.height), () => new Array(this.width).fill(this.PATH));
    randomSeed(seed);
  }

  set_outer_wall() {
    for (let y = 0; y < this.height; ++y) {
      for (let x = 0; x < this.width; ++x) {
        if (x == 0 || y == 0 || x == this.width-1 || y == this.height-1) {
          this.maze[y][x] = this.WALL;
        }
      }
    }
    return this.maze;
  }

  set_maze_kabenobashi() {
    this.set_outer_wall();
  let stack = [];
    for (let y = 2; y < this.height-1; y+=2) {
      for (let x = 2; x < this.width-1; x+=2) {
        stack.push([x,y]);
      }
    }
    while (true) {
      if (stack.length == 0) {
        break;
      }
      stack = shuffle(stack);
      let _point = stack.pop();
      if (this.maze[_point[1]][_point[0]] == this.WALL) {
        continue;
      }
      this.maze[_point[1]][_point[0]] = this.WALL;
      let extend_wall = []
      extend_wall.push([_point[0],_point[1]]);
      while (true) {
        let directions = [];
        if (this.maze[_point[1]-1][_point[0]] == this.PATH && !extend_wall.some(e => e[0] == _point[0] && e[1] == _point[1]-2)) {
          directions.push(0);
        }
        if (this.maze[_point[1]][_point[0]+1] == this.PATH && !extend_wall.some(e => e[0] == _point[0]+2 && e[1] == _point[1])) {
          directions.push(1);
        }
        if (this.maze[_point[1]+1][_point[0]] == this.PATH && !extend_wall.some(e => e[0] == _point[0] && e[1] == _point[1]+2)) {
          directions.push(2);
        }
        if (this.maze[_point[1]][_point[0]-1] == this.PATH && !extend_wall.some(e => e[0] == _point[0]-2 && e[1] == _point[1])) {
          directions.push(3);
        }
        if (directions.length == 0) {
          break;
        }
        let direction = directions[floor(random(directions.length))];
        if (direction == 0) {
          if (this.maze[_point[1]-2][_point[0]] == this.WALL) {
            this.maze[_point[1]-1][_point[0]] = this.WALL;
            break;
          } else {
            this.maze[_point[1]-1][_point[0]] = this.WALL;
            this.maze[_point[1]-2][_point[0]] = this.WALL;
            extend_wall.push([_point[0],_point[1]-2]);
            _point = [_point[0],_point[1]-2];
          }
        } else if (direction == 1) {
          if (this.maze[_point[1]][_point[0]+2] == this.WALL) {
            this.maze[_point[1]][_point[0]+1] = this.WALL;
            break;
          } else {
            this.maze[_point[1]][_point[0]+1] = this.WALL;
            this.maze[_point[1]][_point[0]+2] = this.WALL;
            extend_wall.push([_point[0]+2,_point[1]]);
            _point = [_point[0]+2,_point[1]];
          }
        } else if (direction == 2) {
          if (this.maze[_point[1]+2][_point[0]] == this.WALL) {
            this.maze[_point[1]+1][_point[0]] = this.WALL;
            break;
          }  else {
            this.maze[_point[1]+1][_point[0]] = this.WALL;
            this.maze[_point[1]+2][_point[0]] = this.WALL;
            extend_wall.push([_point[0],_point[1]+2]);
            _point = [_point[0],_point[1]+2];
          }
        } else if (direction == 3) {
          if (this.maze[_point[1]][_point[0]-2] == this.WALL) {
            this.maze[_point[1]][_point[0]-1] = this.WALL;
            break;
          } else {
            this.maze[_point[1]][_point[0]-1] = this.WALL;
            this.maze[_point[1]][_point[0]-2] = this.WALL;
            extend_wall.push([_point[0]-2,_point[1]]);
            _point = [_point[0]-2,_point[1]];
          }
        }
      }
    }
    return this.maze;
  }

  print_maze() {
    for (let col of this.maze) {
      let arr = '';
      for(let cell of col) {
        if (cell == this.WALL) {
          arr += '#';
        } else if (cell == this.PATH) {
          arr += ' ';
        }
      }
      console.log(arr);
    }
  }
}

今回は、以下のように出力される。

###############
#   #     # # #
### # # # # # #
#     # #     #
##### # # #####
#     # #   # #
# # ####### # #
# # # #     # #
# ### ### # # #
#     # # #   #
# ### # # ### #
#   # # # # # #
# ### # ### ###
#   #         #
###############
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A web editor for p5.js, a JavaScript library with the goal of making coding accessible to artists, designers, educators, and beginners.

参考

迷路生成(壁伸ばし法) - Algoful
壁伸ばし法は迷路生成アルゴリズムの一種で...
[Python] 壁伸ばし法による迷路生成
迷路生成のアルゴリズム 迷路生成のアルゴリズムは数多くあります。 Maze Classification -M…
自動生成迷路

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