constructor() {

    this.x = random(-width, width);

    this.y = random(-height, height);

    this.z = random(width);

    this.pz = 0;

  }

​

  update() {

    this.z = this.z - speed;

    if (this.z < 1) {

      this.z = width;

      this.x = random(-width, width);

      this.y = random(-height, height);

      this.pz = this.z;

    }

  }

​

  show() {

    fill(255);

    noStroke();

​

    this.sx = map(this.x / this.z, 0, 1, 0, width);

    this.sy = map(this.y / this.z, 0, 1, 0, height);

    this.r = map(this.z, 0, width, 16, 0);

    // ellipse(this.sx, this.sy, this.r, this.r);

    this.px = map(this.x / this.pz, 0, 1, 0, width);

    this.py = map(this.y / this.pz, 0, 1, 0, height);

    this.pz = this.z;

    stroke(255);

    line(this.px, this.py, this.sx, this.sy);

  }

}