let permissionGranted = false

let nonios13device = false

​

let cx, cy

​

function setup() {

  createCanvas(windowWidth, windowHeight)

​

  if (typeof(DeviceOrientationEvent) !== 'undefined' && typeof(DeviceOrientationEvent.requestPermission) === 'function') {

    button = createButton('click to allow access to sensors')

    button.style("font-size", "24px")

    button.center()

    button.mousePressed(requestAccess)

  } else {

    // non ios 13 devices

    nonios13device = true

  }

}

​

function draw() {

  if (!permissionGranted && !nonios13device) {

    // I am simply not running draw, but you can treat in different ways.

    return

  }

​

  background('lightblue')

  textSize(72)

  text(rotationX, 100, 100)

}

​

function requestAccess() {

  DeviceOrientationEvent.requestPermission()

    .then(response => {

      if (response == 'granted') {

        permissionGranted = true

      }

    })

    .catch(console.error)

  button.remove()

}