Spotlight

lines = []

n = 200;

​

function setup() {

  colorMode(HSB)

  createCanvas(600, 900);

  strokeWeight(40);

  for (i = 0; i < n; i++){

    lines.push({

      x1 : random(width),

      x2 : random(3 * width / 8, 5 * width / 8),

      vl : random(-10, 10),

      cl : color(random(48, 96),

                 100,

                 100,

                 0.1

                )

    });

  }

}

​

function draw() {

  background(0);

  for (i = 0; i < n; i++){

    if (abs(lines[i].x1 - lines[i].x2) >= width * 1.5) {

      lines[i].vl *= -1;

    }

    lines[i].x2 += lines[i].vl;

    stroke(lines[i].cl);

    line(lines[i].x1, 0, lines[i].x2, height);

  }

}