// and branch out somewhere else

//let color =0;

function index(i, j){

    if (i < 0 || j < 0 || i > cols - 1 || j > rows - 1) {

        return -1;

    }

    return i + j * cols;

}

​

//

function removeWalls(a, b) {

    let x = a.i - b.i;

    if (x === 1) {

      a.walls[3] = false;

      b.walls[1] = false;

    } else if (x === -1) {

      a.walls[1] = false;

      b.walls[3] = false;

    }

​

    let y = a.j - b.j;

    if (y === 1) {

      a.walls[0] = false;

      b.walls[2] = false;

    } else if (y === -1) {

      a.walls[2] = false;

      b.walls[0] = false;

    }

  }

​

function Cell(i, j,color) {

    this.i = i;

    this.j = j;

    this.color = color;

    this.walls = [true, true, true, true];

​

    this.visited = false;

​

    this.checkNeighbors = function() {

      let neighbors = [];

​

      let top = grid[index(i, j - 1)];

      let right = grid[index(i + 1, j)];

      let bottom = grid[index(i, j + 1)];

      let left = grid[index(i - 1, j)];

​

      if (top && !top.visited) {

        neighbors.push(top);

      }

      if (right && !right.visited) {

        neighbors.push(right);

      }

      if (bottom && !bottom.visited) {

        neighbors.push(bottom);

      }

      if (left && !left.visited) {

        neighbors.push(left);

      }

​

​

      if (neighbors.length > 0) {

        let r = floor(random(0, neighbors.length));

        return neighbors[r];

      } else {

        return undefined;

      }

    };

​

    this.highlight = function() {

      let x = this.i * w;

      let y = this.j * w;

      noStroke();

      //color ++;

      fill(color, color, color,100);

      rect(x, y, w, w);

      line(x+w/2,y+w/2,w+x/2,w+y/2);

    };

​

​

    this.show = function() {

      let x = this.i * w;

      let y = this.j * w;

      noStroke();

​

      if (this.walls[0]) {

        line(x, y, x + w, y);

      }

      if (this.walls[1]) {

        line(x + w, y, x + w, y + w);

      }

      if (this.walls[2]) {

        line(x + w, y + w, x, y + w);

      }

      if (this.walls[3]) {

        line(x, y + w, x, y);

      }

​

​

      if (this.visited) {

        noStroke();

        color = color+0.1;

        fill(color, color, color,250);

​

        rect(x, y, w, w);

        //line(x+w/2,y+w/2,w+x/2,w+y/2);

      }

    };

  }

​

​

  let current;

  let cols, rows;

  let w = 10;

  let grid = [];

  let stack = []; // what is the stack? is a term from computer science. Is like an array, it is a list of things one of the top of each other.

  // things are getting pushed on the top of the stack. push!

  // when take things out, you take them from the top of the pile, meaning the last item added. pop! The last thing in, is the first thing out

​

  function setup() {

    createCanvas(800, 800);

    cols = floor(width / w);

    rows = floor(height / w);

    let color = 0;

    for (let j = 0; j < rows; j++) {

      for (let i = 0; i < cols; i++) {

        var cell = new Cell(i, j, color);

        grid.push(cell);

      }

    }

​

    current = grid[0];

    background(0)

  }

​

  function draw() {

    background(51);

    //color ++;

    for (let i = 0; i < grid.length; i++) {

      grid[i].show();

    }

​

    current.visited = true;

    current.highlight(); // let's add a function that tells us where the cursor is.

    // step 1 in the wiki page. Pick a random neighbour and mark it as visie

    let next = current.checkNeighbors();

​

    if (next) {

​

        next.visited = true;

​

        // STEP 2

        // check the wiki page! simply push things in

        stack.push(current);

​

        // step 3, remove walls

        removeWalls(current, next);

​

        // step 4 in the wiki page

        current = next;

    // here is where the magic happen. If there is no an available free neighbor,

    // we check if our stack it is not empty. If it is not, we take the last cell cell insert as our new current cursor.

    // We are done!!

    } else if (stack.length > 0) {

        current = stack.pop();

    }

​

  }

​

  // how about changing the colors depending on how many time they get visited

  // what about adding horizzontal or vertical bias?

​