//from coding challenge  https://youtu.be/HyK_Q5rrcr4 

// In my version i treated creating maze as erasing lines ,So there is no need for storing objects in array ,iterating them with multiple for loops 

// so my version will work superfast at any number of cells

​

​

let s=15  //size of cell

let grid=[]

let Current

let stack=[]

let pos

let off=1

let small=2*off

let large=s-2*off

let gap=small/2

let end=false

let next,pre

let forward=true

​

function setup() {

  createCanvas(windowWidth,windowHeight);

  background(0);

  stroke(255);

  strokeWeight(1);

  noFill()

 cols=floor(width/s);

 rows=floor(height/s);

  for (var i = 0; i <rows ; i++) {

    let gridx=[]

    for (var j = 0; j <cols ; j++) {

        let c=new Cell(j,i)

        gridx.push(c)

        rect(j*s,i*s,s,s)

    }

    grid.push(gridx)

  }

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

        for (var j = 0; j < grid[i].length; j++) {

            grid[i][j].calcneighbours()

         } 

    }

  Current=grid[0][0]

  pre=grid[0][0]

}

​

function draw() {

    if(Current){

    Current.current=true

    Current.active=true

    if (forward) {fill(0,230,0)}

    else {fill(230,0,0)}

    rect(Current.x+off,Current.y+off,s-small,s-small)

    fill(0)

    rect(pre.x+off,pre.y+off,s-small,s-small)

    if (Current.neighbour.length!=0){

        Current.neighbourupdate()

        Current.current=false

        if (Current.neighbour.length!=0){

            forward=true

            next=random(Current.neighbour)

        Current.eraselines(Current,next)

        pos = Current.eraselines(Current,next)

        erasepath()

        pre=Current

        Current=next

        stack.push(Current)

        }

    }

     else {

        forward=false

            pre=Current

          Current=stack.pop()       

        }

    }

​

    else {

        if(!end){

            console.log('maze generated');

    }

        end=true

​

        fill(0)

        rect(pre.x+off,pre.y+off,s-small,s-small)

        }

}

​

function erasepath(){

        let x=Current.x

        let y=Current.y

        noStroke()

        fill(0);

        if (pos==1) {rect(x+off,y-gap,large,small);}

        else if (pos==2) {rect(x+s-gap,y+off,small,large);}

        else if (pos==3) {rect(x+off,y-gap+s,large,small);}

        else if (pos==4) {rect(x-gap,y+off,small,large);}

        noFill()    

​

}

class Cell{

    constructor(x,y){

        this.i=x;

        this.j=y;

        this.x=x*s;

        this.y=y*s;

        this.wall=[true,true,true,true]

        this.active=false

        this.current=false

        this.neighbour=[]

    }

    calcneighbours(){

        let x=this.j;

        let y=this.i

        this.index=function(x,y){if (x<0 || y<0 || x>rows-1 || y>cols-1) {

            return false

        }

        return true}

​

        if(this.index(x-1,y)){this.neighbour.push(grid[x-1][y])}

        if(this.index(x,y+1)){this.neighbour.push(grid[x][y+1])}

        if(this.index(x+1,y)){this.neighbour.push(grid[x+1][y])}

        if(this.index(x,y-1)){this.neighbour.push(grid[x][y-1])}

    }

    neighbourupdate(){

​

        for (var i = this.neighbour.length-1; i >-1 ; i--) {

            if(this.neighbour[i].active){

                this.neighbour.splice(i,1)

            }

        }

    }

    eraselines(c,n){

        if (c.j>n.j) {

            //pos=top

            return 1

        }

        if (c.i<n.i) {

            //pos=right

            return 2

        }

        if (c.j<n.j) {

            //pos=bottom

            return 3

        }

        if (c.i>n.i) {

            //pos=left

            return 4

        }

​

    }

​

​

}