pos: {x: 0, y:0},

  vel: {x:0, y:0},

  radius: 10,

  mass: 11

}

​

let prev_ball;

​

const G = {x:0, y:9.8};

​

​

​

let dt = 0.01;

let currentTime;

let accumulator = 0.0;

​

​

​

​

function setup() {

  createCanvas(400, 400);

  ball.pos = {x: width/2, y:20};

  currentTime = millis() /1000;

  prev_ball = ball;

​

  mainLoop();

}

​

​

​

​

​

const verlet_integration = (obj, acc, dt) => {

  obj.pos.y += dt * (obj.vel.y * acc.y /2);

  obj.vel.y += dt * (acc.y + acc.y) /2;

  obj.pos.x += dt * (obj.vel.x * acc.x /2);

  obj.vel.x += dt * (acc.x + acc.x) /2;

}

​

​

const getAcceleration = (force, mass) => {

  return {x:force.x/mass , y: force.y/mass};

}

​

​

function render(obj) {

    background(12);

  ellipseMode(CENTER);

  fill(255);

  ellipse(obj.pos.x, obj.pos.y, obj.radius, obj.radius)

}

​

const lerpp = (a, b, mu) => {

  return a * mu + b * (1-mu)

}

​

function simulate(dt) {

  let force = {x:0, y: 0};

  let acc = getAcceleration(force, ball.mass);

  acc.x += G.x;

  acc.y += G.y;

  verlet_integration(ball, acc, dt);

  if(ball.pos.y > height) {

    ball.pos.y = 0;

    ball.pos.x = random(0, width);

    ball.vel.x = 0;

    ball.vel.y = 0;

​

  }

}

​

​

let tickCount = 0;

​

function mainLoop() {

  simulate(dt);

  tickCount++;

  setInterval(mainLoop, 100);

}

​

​

function mousePressed() {

  dt = 1/61;

}

​

function mouseReleased() {

  dt = 0.01;

​

}

​

​

​

function draw() {

  let newTime = millis() /1000;

  let frameTime = newTime - currentTime;

  if ( frameTime > 0.25 )

            frameTime = 0.25;

  currentTime = newTime;

  accumulator += (frameTime);

  while (accumulator >= dt ) {

    prev_ball       = ball;

    prev_ball.pos.x = ball.pos.x; 

    prev_ball.pos.y = ball.pos.y;

    prev_ball.vel.x = ball.vel.x;

    prev_ball.vel.y = ball.vel.y;

    //simulate(dt);

    accumulator -= dt;

  }

  const mu = accumulator /dt;

  let newBall_x = lerpp(ball.pos.x, prev_ball.pos.x, mu);

  let newBall_y = lerpp(ball.pos.y, prev_ball.pos.y, mu);

  let newBall = ball;

  newBall.pos = {x: newBall_x, y:newBall_y};

  render(newBall);

}