let alpha = 255;

​

function setup() {

  createCanvas(640, 480);

  textSize(18);

}

​

function draw() {

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

  background(map(rVal, 0, 1023, 0, 255), 255, 255);

​

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

  fill(255, 0, 255, map(alpha, 0, 1023, 0, 255));

​

  if (!serialActive) {

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

  } else {

    text("Connected", 20, 30);

​

    // Print the current values

    text("rVal = " + str(rVal), 20, 50);

    text("alpha = " + str(alpha), 20, 70);

  }

}

​

function keyPressed() {

  if (key == " ") {

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

    setUpSerial();

  }

}

​

// 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 == 2) {

      // 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

      rVal = int(fromArduino[0]);

      alpha = int(fromArduino[1]);

    }

​

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

    //SEND TO ARDUINO HERE (handshake)

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

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

    writeSerial(sendToArduino);

  }

}

​

​