let gravity;

let position;

let acceleration;

let wind;

let drag = 0.99;

let mass = 50;

let pot;

let left = 0;

let right = 0;

let rcolor;

let gcolor;

let bcolor;

​

function setup() {

  createCanvas(640, 360);

  noFill();

  position = createVector(width / 2, 0);

  velocity = createVector(0, 0);

  acceleration = createVector(0, 0);

  gravity = createVector(0, 0.5 * mass);

  wind = createVector(0, 0);

  rcolor = random(0, 255);

  gcolor = random(0, 255);

  bcolor = random(0, 255);

}

​

function draw() {

  background(255);

  if (serialActive) {

    applyForce(wind);

    applyForce(gravity);

    velocity.add(acceleration);

    velocity.mult(drag);

    position.add(velocity);

    acceleration.mult(0);

    fill(rcolor, gcolor, bcolor);

    ellipse(position.x, position.y, mass, mass);

    if (position.y > height - mass / 2) {

      velocity.y *= -0.9; // A little dampening when hitting the bottom

      position.y = height - mass / 2;

      left = (left + 1) % 2;

      if (left == 0) {

        right = 1;

      } else {

        right = 0;

      }

    }

  } else {

    fill(255, 0, 255, 255);

    text("Press Right Arrow to select Serial Port", 20, 30);

  }

}

​

function applyForce(force) {

  // Newton's 2nd law: F = M * A

  // or A = F / M

  let f = p5.Vector.div(force, mass);

  acceleration.add(f);

}

​

function keyPressed() {

  if (keyCode == RIGHT_ARROW) {

    // important to have in order to start the serial connection!!

    setUpSerial();

  }

  if (key == " ") {

    mass = random(15, 80);

    position.y = -mass;

    velocity.mult(0);

    rcolor = random(0, 255);

    gcolor = random(0, 255);

    bcolor = random(0, 255);

    left = 0;

    right = 0;

  }

}

​

// This function will be called by the web-serial library

// with each new *line* of data. The serial library reads

// the data until the newline and then gives it to us through

// this callback function

function readSerial(data) {

  ////////////////////////////////////

  //READ FROM ARDUINO HERE

  ////////////////////////////////////

​

  if (data != null) {

    // make sure there is actually a message

    // split the message

    let fromArduino = split(trim(data), ",");

    // if the right length, then proceed

    if (fromArduino.length == 1) {

      // only store values here

      // do everything with those values in the main draw loop

​

      // We take the string we get from Arduino and explicitly

      // convert it to a number by using int()

      // e.g. "103" becomes 103

      wind.x = map(float(fromArduino[0]), 0, 1023, 5, -5);

    }

​

    //////////////////////////////////

    //SEND TO ARDUINO HERE (handshake)

    //////////////////////////////////

    let sendToArduino = left + "," + right + "\n";

    writeSerial(sendToArduino);

  }

}

​