let columns = 10;

let rows = 5;

let wColumns;

let hRows;

let add;

​

​

function setup() {

  createCanvas(400, 200);

  wColumns = width / columns;

  hRows= height / rows;

  stroke(255);

}

​

function draw() {

  background(225);

  //for(r = 0; r<=columns; r++ && d = 0; d<=rows; d++

  for(r = 0; r<=columns; r++) {

    for (d = 0; d<=rows; d++) {  

  let x = r*wColumns;

  let y = d*hRows;

      //the color part learned from other people's code, still trying to understand why  

      let spotColor = dist(mouseX, mouseY, x, y);

      spotColor = map(spotColor, 0, dist(0, 0, width, height), 255, 0);

      fill(spotColor);

      rect(x,y,wColumns,hRows);

    }

  }

}