const NUM_LINES = 100;

​

function setup() {

  createCanvas(400, 400);

  for (let i = 0; i < NUM_LINES; i += 1) {

    // lines[i] = random(0, 255);

    lines[i] = 255*abs(cos(i*0.1));

  }

}

​

function draw() {

  background(255);

  for (let i = 0; i < NUM_LINES; i += 1) {

    stroke(lines[i]);

    let xPos = map(i, 0, NUM_LINES, 0, width);

    line(xPos, 0, xPos, height);

  }

}