const pendulums = [];

​

function setup() {

  createCanvas(800, 600);

  // Create the pendulums

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

    const pendulum = createPendulum(width / 2, 200, 100, random(0.2, 0.5), random(0.2, 0.5));

    pendulums.push(pendulum);

  }

}

​

function draw() {

  background(255);

  // Update and draw the pendulums

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

    const pendulum = pendulums[i];

    pendulum.update();

    pendulum.draw();

  }

}

​

function createPendulum(x, y, length1, angle1, angle2) {

  const p = {

    x: x,

    y: y,

    length1: length1,

    length2: length1,

    angle1: angle1,

    angle2: angle2,

    angle1_v: 0,

    angle2_v: 0,

    gravity: 0.5,

    update: function() {

      const num1 = -this.gravity * (2 * this.length1 * m1 + m2) * sin(this.angle1);

      const num2 = -m2 * this.gravity * sin(this.angle1 - 2 * this.angle2);

      const num3 = -2 * sin(this.angle1 - this.angle2) * m2;

      const num4 = this.angle2_v * this.angle2_v * this.length2 + this.angle1_v * this.angle1_v * this.length1 * cos(this.angle1 - this.angle2);

      const den = this.length1 * (2 * m1 + m2 - m2 * cos(2 * this.angle1 - 2 * this.angle2));

      const angle1_a = (num1 + num2 + num3 * num4) / den;

      const num5 = 2 * sin(this.angle1 - this.angle2);

      const num6 = (this.angle1_v * this.angle1_v * this.length1 * (m1 + m2));

      const num7 = this.gravity * (m1 + m2) * cos(this.angle1);

      const num8 = this.angle2_v * this.angle2_v * this.length2 * m2 * cos(this.angle1 - this.angle2);

      const den2 = this.length2 * (2 * m1 + m2 - m2 * cos(2 * this.angle1 - 2 * this.angle2));

      const angle2_a = (num5 * (num6 + num7 + num8)) / den2;

      this.angle1_v += angle1_a;

      this.angle2_v += angle2_a;

      this.angle1 += this.angle1_v;

      this.angle2 += this.angle2_v;

    },

    draw: function() {

      const x1 = this.x + this.length1 * sin(this.angle1);

      const y1 = this.y + this.length1 * cos(this.angle1);

      const x2 = x1 + this.length2 * sin(this.angle2);

      const y2 = y1 + this.length2 * cos(this.angle2);

      stroke(0);

      line(this.x, this.y, x1, y1);

      line(x1, y1, x2, y2);

      fill(0);

      ellipse(x1, y1, m1, m1);

      ellipse(x2, y2, m2, m2);

    }

  };

  return p;

}

​