​

let movers = [];

let attractor;

​

function setup() {

  createCanvas(600, 600);

  for (let i = 0; i < 30; i++) {

    let x = random(width);

    let y = random(height);

    let m = random(50, 150);

    movers[i] = new Mover(x, y, m);

  }

  attractor = new Attractor(width / 2, height / 2, 100);

  background(0);

}

​

function draw() {

  background(0);

  for (let mover of movers) {

    mover.update();

    mover.show();

    attractor.attract(mover);

  }

​

  attractor.show();

  attractor.update();

  attractor.control();

}

​

class Attractor {

  constructor(x, y, m) {

    this.pos = createVector(x, y);

    this.mass = m;

    this.r = sqrt(this.mass) * 2;

    this.vel = p5.Vector.random2D(0,0);

  }

​

  attract(mover) {

    let force = p5.Vector.sub(this.pos, mover.pos);

    let distanceSq = constrain(force.magSq(), 400, 800);

    let G = 3;

    let strength = (G * (this.mass * mover.mass)) / distanceSq;

    force.setMag(strength);

    mover.applyForce(force);

  }

  update(){

    this.pos.add(this.vel);

  }

  control(){

     if (keyIsDown(38)){

      this.vel.add(0.06, -0.06);

    } else if (keyIsDown(40)){

      this.vel.add(-0.06, 0.06);

    }

    if (keyIsDown(37)){

      this.vel.add(-0.06);

    } else if (keyIsDown(39)){

      this.vel.add(0.06);

    }

  }

​

  show() {

    noStroke();

    fill(255);

    ellipse(this.pos.x, this.pos.y, this.r * 1);

  }

}

​

class Mover {

  constructor(x, y, m) {

    this.pos = createVector(x, y);

    this.vel = p5.Vector.random2D();

    this.vel.mult(3);

    this.acc = createVector(0, 0);

    this.mass = m;

    this.r = sqrt(this.mass) * 2;

  }

​

  applyForce(force) {

    let f = p5.Vector.div(force, this.mass);

    this.acc.add(f);

  }

​

  update() {

    this.vel.add(this.acc);

    this.pos.add(this.vel);

    this.acc.set(0, 0);

  }

​

  show() {

    noStroke();

    fill(255, 120, 50);

    ellipse(this.pos.x, this.pos.y, this.r * 0.5);

  }

}