let first = 262;

​

// Create an array of frequencies for the C Major scale based on the frequency of Middle C.

let frequencies = [

  first,             // Middle C

  first * 9/8,       // D

  first * 5/4,       // E

  first * 4/3,       // F

  first * 3/2,       // G

  first * 5/3,       // A

  first * 15/8,      // B

  first * 2          // C (one octave higher)

];

​

// Initialize an array to hold Oscillator objects.

let oscillators = [];

​

// Initialize an array to track whether each note is being played.

let noteStates = [false, false, false, false, false, false, false, false];

​

function setupXylophone() {

  // Create an Oscillator for each frequency.

  for (let freq of frequencies) {

    let osc = new Oscillator(freq);

    osc.amp(0);

    osc.start();

    oscillators.push(osc);

  }

}

​

function drawXylophone() {

  // Draw a rectangle for each note.

  for (let i = 0; i < 8; i++) {

    if (noteStates[i]) {

      fill(100, 200, 100); // Highlight color when note is playing.

    } else {

      fill(200); // Default color when note is not playing.

    }

    rect(i * 45 + 20, 200, 40, 100); // Position each rectangle with some spacing.

    fill(0)

    text("(" + (i+1) + ")", i * 47 + 25, 320) //display key number

  }

}

​

function playNote(noteIndex) {

  oscillators[noteIndex].amp(1);

  noteStates[noteIndex] = true;

}

​

function stopNote(noteIndex) {

  oscillators[noteIndex].amp(0);

  noteStates[noteIndex] = false;

}

​