// grid
// add amount to y

let gridWidth,gridHeight;

function setup() {
  createCanvas(windowWidth, windowHeight);
}

function draw() {
  background(255);
  
  gridWidth=width/20
  gridHeight=height/3
    
  
  for(x=0;x<=width;x+=gridWidth+10){
    for(y=0;y<3;y++){
      strokeWeight(2)
      rectMode(CENTER);
      rect(x,y*gridHeight+1/2*gridHeight,
           gridWidth,gridHeight-height/15+random(-height/20,height/20))
      
    }
  }
  noLoop();
}