class Segment {

  /* Unlike in Java, JavaScript does not implement

   * function overloading, which means we cannot simply have

   * two different constructors for our Segment class as Shiffman does in

   * his pde example. Instead, we must have one constructor function

   * which behaves differently depending on the type of arguments we pass.

   */

  constructor(point, len, i) {

    if (point.hasOwnProperty("angle")) { // point is probably a Segment

​

      this.par = point;

      this.a = this.par.b.copy();

​

    } else {

​

      this.par = false;

      this.a = point;

​

    }

​

    this.b = new p5.Vector();

    this.angle = 0;

    this.sw = map(i, 0, 20, 1, 10);

    this.len = len;

    this.calculateB();

  }

​

​

  follow(tx, ty) {

  /* Shiffman used function overloading here too, but since we can't

   * in JavaScript we instead check whether or not ty is undefined. */

    if (typeof(ty) == "undefined") {

​

      let targetX = this.child.a.x;

      let targetY = this.child.a.y;

      this.follow(targetX, targetY);

​

    } else {

​

      let target = new p5.Vector(tx, ty);

      let dir = p5.Vector.sub(target, this.a);

      this.angle = dir.heading();

​

      dir.setMag(this.len);

      dir.mult(-1);

      this.a = p5.Vector.add(target, dir);

​

    }

  }

​

​

  calculateB() {

    let dx = this.len * cos(this.angle);

    let dy = this.len * sin(this.angle)

    this.b.set(this.a.x + dx, this.a.y + dy);

  }

​

​

  update() {

    this.calculateB();

  }

​

​

  show() {

    stroke(255);

    strokeWeight(9);

    line(this.a.x, this.a.y, this.b.x, this.b.y);

  }

}

​