createCanvas(700, 700);

  background("rgb(255,0,190)");

}

​

function draw() {

  // loop 10 times

  for (let index = 0; index < 12; index++) {

    // use the index to calculate the y position

    let y = index * 41;

​

    for (let index2 = 0; index2 < 12; index2++) {

      // use the index to calculate the y position

      let x = index2 * 41;

​

      circle(y + 25, 30, 30);

​

    }

  }

  // add 20 because that is half of the size

​

  let c = map(mouseY, 0, width, 0, 300);

  fill(c);

​

  describe(

    "A circle changes color from black to white as the mouse moves from left to right."

  );

}

​

​

​