this.x = random(width); 

    this.y = random(-500, -50);

    this.z = random(0, 20);

    this.len = map(this.z, 0, 20, 10, 20);

    this.yspeed = map(this.z, 0, 20, 1, 20);

​

    this.update = function() {

        this.y += this.yspeed;

        let grav = map(this.z, 0, 20, 0, 0.2);

        this.yspeed += grav;

        if (this.y >= height) {

            this.y = random(-200, -100);

            this.yspeed = map(this.z, 0, 20, 4, 9);

        }

    }

​

    this.display = function() {

        let thick = map(this.z, 0, 20, 1, 3);

        strokeWeight(thick);

        stroke(138, 43, 226);

        line(this.x, this.y, this.x, this.y + this.len);

    }

}