// The Coding Train / Daniel Shiffman

// https://thecodingtrain.com/CodingChallenges/160-spring-forces.html

// https://youtu.be/Rr-5HiXquhw

​

// Simple Spring: https://editor.p5js.org/codingtrain/sketches/dcd6-2mWa

// Spring Vector: https://editor.p5js.org/codingtrain/sketches/_A2pm_SSg

// Spring OOP: https://editor.p5js.org/codingtrain/sketches/9BAoEn4Po

// Soft Spring: https://editor.p5js.org/codingtrain/sketches/S5dY7qjxP

​

class Spring {

  constructor(k, restLength, a, b) {

    this.k = k;

    this.restLength = restLength;

    this.a = a;

    this.b = b;

  }

​

  update() {

    let force = p5.Vector.sub(this.b.position, this.a.position);

    let x = force.mag() - this.restLength;

    force.normalize();

    force.mult(this.k * x);

    this.a.applyForce(force);

    force.mult(-1);

    this.b.applyForce(force);

  }

​

  show() {

    strokeWeight(4);

    stroke(255);

    line(

      this.a.position.x,

      this.a.position.y,

      this.b.position.x,

      this.b.position.y

    );

  }

}

​