<p>[page:Function callback] — The function will be called every available frame. If `null` is passed it will stop any already ongoing animation.</p>
<p>A build in function that can be used instead of [link:https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame requestAnimationFrame]. For WebVR projects this function must be used.</p>
<p>A built in function that can be used instead of [link:https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame requestAnimationFrame]. For WebVR projects this function must be used.</p>