requestAnimationFrame
A browser-independent function to request a new animation frame. This is used to create an application's draw loop as shown in the example below.
Parameters:
| Name | Type | Description | 
|---|---|---|
| callback | Function | The function to call when animation is ready. | 
Returns:
	 An ID that can be passed to @{link cancelAnimationFrame} to cancel the request.
         
    
    
        Example
// Create a draw loop using requestAnimationFrame. The
// tick callback function is called for every animation frame.
function tick() {
  scene.render();
  Cesium.requestAnimationFrame(tick);
}
tick();
    
	
	
