let pulse = 255;

let left = 0;

let right = 0;

let stars = [];

let ellipseVisible = false;

​

function setup() {

  createCanvas(600, 600);

  textSize(18);

  createStars();

}

​

function draw() {

  // one value from Arduino controls the background's red color

  background(0);

​

  // the other value controls the text's transparency value

  fill(255, 255, 255);

  strokeWeight(0);

​

  if (!serialActive) {

    text("Press Space Bar to select Serial Port", 20, 30);

  } else {

    text("Connected", 20, 30);

  }

​

  drawingContext.shadowBlur = 80;

  drawingContext.shadowColor = color(255);

​

  if (pulse > 0 && !ellipseVisible) {

    ellipseVisible = true;

  }

​

  if (ellipseVisible) {

    let ellipseSize = map(pulse, 0, 255, 10, 100);

    ellipse(width / 2, height / 2, ellipseSize);

    moveStars();

    displayStars();

  }

}

​

function createStars() {

  for (let i = 0; i < 100; i++) {

    let x = random(width);

    let y = random(height);

    let radius = random(1, 3);

    let speedX = random(1, 3) * (random() > 0.5 ? 1 : -1);

    let speedY = random(1, 3) * (random() > 0.5 ? 1 : -1);

    stars.push({ x, y, radius, speedX, speedY });

  }

}

​

function moveStars() {

  for (let star of stars) {

    star.x += star.speedX;

    star.y += star.speedY;

​

    if (star.x < 0 || star.x > width || star.y < 0 || star.y > height) {

      star.x = random(width);

      star.y = random(height);

    }

  }

}

​

function displayStars() {

  fill(255);

  noStroke();

​

  for (let star of stars) {

    ellipse(star.x, star.y, star.radius * 2, star.radius * 2);

  }

}

​

function updateStars() {

  let rValMapped = map(rVal, 0, 255, -0.1, 0.1);

  let pulseMapped = map(pulse, 0, 255, 1, 3);

  let pulsingFactor = map(pulse, 0, 255, 0.5, 2);

​

  for (let star of stars) {

    star.speedX += rValMapped;

    star.speedY += rValMapped;

​

    star.radius = pulseMapped * pulsingFactor;

  }

}

​

function keyPressed() {

  if (key == " ") {

    setUpSerial();

  }

}

​

function readSerial(data) {

  if (data != null) {

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

    if (fromArduino.length == 2) {

      rVal = fromArduino[0];

      pulse = fromArduino[1];

    }

​

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

    writeSerial(sendToArduino);

  }

}

​