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(64);

    stroke(0);

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

    strokeWeight(60);

    stroke(255);

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

    strokeWeight(4);

    stroke(0);

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

    // perpendiculine(this.a.position.x, this.a.position.y, this.b.position.x, this.b.position.y);

  }

}

​

function perpendiculine(x1, y1, x2, y2){

  // let ang = atan2(x1,y1,x2- x1, y2 - y1);

  // ang += PI/2;

  // let x3 = 

  let a = (y2 - y1) / (x2 - x1);

  // let y = a * x 

  let b = y - a*x;

  y3 = a *(x2-x1) + y1;

  line(x1, y1, x1 + x3, y1 + y3);

}

​

​