constructor(attached, location, k) {

    this.attached = attached;

    this.location = location;

    this.equilPos = this.location.copy();

    this.k = k;

    this.r = 10;

​

    this.velocity = createVector(0, 0);

    this.acceleration = createVector(0, 0);

  }

​

  stop() {

    this.acceleration.mult(0);

    this.velocity.mult(0);

    // this.location.set(this.equilPos);

    this.stopped = true; 

  }

​

  applyForce(force) {

    this.acceleration.add(force);

  }

​

  update() {

    if (this.stopped) {

      this.stopped = false; 

      return 

    }

    this.applyForce(gravity)

    if (p5.Vector.dist(this.location, this.equilPos) > 0) {

      let force = this.location.copy();

      force.sub(this.equilPos);

      force.mult(-this.k);

      this.applyForce(force);

    }

    this.acceleration.div(timestep);

    this.velocity.add(this.acceleration);

    this.velocity.mult(0.99999);

    this.location.add(this.velocity);

  }

​

  show() {

    strokeWeight(2);

    stroke(0);

    line(this.attached.x, this.attached.y, this.location.x, this.location.y);

    fill(35, 60, 255);

    circle(this.location.x, this.location.y, this.r);

  }

}

​

let bob;

let timestep = 1000;

let setting = false

let gravity ;

let gravitySlider

​

function setup() {

  createCanvas(400, 400);

  bob = new Bob(createVector(200, 50), createVector(200, 200), 3e-5);

  bob.location = createVector(200, 200);

  let b = createButton("Stop");

  b.mousePressed(() => {

    bob.stop();

  });

  gravity = createVector(0, 0.001)

  gravitySlider = createSlider(0, 0.01, 0.0001, 0.00001)

  gravitySlider.input(() => {

    gravity.set(0, gravitySlider.value())

  })

}

​

function mousePressed() {

  if (setting) return 

  if (mouseX >= 0 && mouseX < width && mouseY >= 0 && mouseY < height) {

      bob.location.set(mouseX, mouseY);

    setting = true 

    }

}

​

function mouseReleased() {

  setting = false 

}

​

function draw() {

  background(220);

  for (let i = 0; i < timestep; i++) {

    bob.update();

  }

  bob.show();

​

​

​

  noStroke();

  fill(255);

  textSize(14);

  text(bob.location, 10, 15);

  text(bob.velocity, 10, 45);

  text(bob.acceleration, 10, 70);

}

​