VRDisplay: requestAnimationFrame() method
=========================================

**Deprecated:** This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

**Non-standard:** This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The **`requestAnimationFrame()`** method of the `VRDisplay` interface is a special implementation of `Window.requestAnimationFrame` containing a callback function that will be called every time a new frame of the `VRDisplay` presentation is rendered:

**Note:** This method was part of the old WebVR API. It has been superseded by the WebXR Device API.

* When the `VRDisplay` is not presenting a scene, this is functionally equivalent to `Window.requestAnimationFrame`.
* When the `VRDisplay` is presenting, the callback is called at its native refresh rate.
Syntax
------


```js
requestAnimationFrame(callback)
```

### Parameters

`callback`

A callback function that will be called every time a new frame of the `VRDisplay` presentation is rendered.

### Return value

A long representing the handle of the `requestAnimationFrame()` call. This can then be passed to a `VRDisplay.cancelAnimationFrame()` call to unregister the callback.

Examples
--------


```js
const frameData = new VRFrameData();
let vrDisplay;

navigator.getVRDisplays().then((displays) => {
  vrDisplay = displays[0];
  console.log("Display found");
  // Starting the presentation when the button is clicked: It can only be called in response to a user gesture
  btn.addEventListener("click", () => {
    vrDisplay.requestPresent([{ source: canvas }]).then(() => {
      drawVRScene();
    });
  });
});

// WebVR: Draw the scene for the WebVR display.
function drawVRScene() {
  // WebVR: Request the next frame of the animation
  vrSceneFrame = vrDisplay.requestAnimationFrame(drawVRScene);

  // Populate frameData with the data of the next frame to display
  vrDisplay.getFrameData(frameData);

  // You can get the position, orientation, etc. of the display from the current frame's pose
  const curFramePose = frameData.pose;
  const curPos = curFramePose.position;
  const curOrient = curFramePose.orientation;

  // Clear the canvas before we start drawing on it.

  gl.clear(gl.COLOR\_BUFFER\_BIT | gl.DEPTH\_BUFFER\_BIT);

  // WebVR: Create the required projection and view matrix locations needed
  // for passing into the uniformMatrix4fv methods below

  const projectionMatrixLocation = gl.getUniformLocation(
    shaderProgram,
    "projMatrix",
  );
  const viewMatrixLocation = gl.getUniformLocation(shaderProgram, "viewMatrix");

  // WebVR: Render the left eye's view to the left half of the canvas
  gl.viewport(0, 0, canvas.width \* 0.5, canvas.height);
  gl.uniformMatrix4fv(
    projectionMatrixLocation,
    false,
    frameData.leftProjectionMatrix,
  );
  gl.uniformMatrix4fv(viewMatrixLocation, false, frameData.leftViewMatrix);
  drawGeometry();

  // WebVR: Render the right eye's view to the right half of the canvas
  gl.viewport(canvas.width \* 0.5, 0, canvas.width \* 0.5, canvas.height);
  gl.uniformMatrix4fv(
    projectionMatrixLocation,
    false,
    frameData.rightProjectionMatrix,
  );
  gl.uniformMatrix4fv(viewMatrixLocation, false, frameData.rightViewMatrix);
  drawGeometry();

  function drawGeometry() {
    // draw the view for each eye
  }

  // …

  // WebVR: Indicate that we are ready to present the rendered frame to the VR display
  vrDisplay.submitFrame();
}
```


**Note:** You can see this complete code at raw-webgl-example.

Specifications
--------------

This method was part of the old WebVR API that has been superseded by the WebXR Device API. It is no longer on track to becoming a standard.

Until all browsers have implemented the new WebXR APIs, it is recommended to rely on frameworks, like A-Frame, Babylon.js, or Three.js, or a polyfill, to develop WebXR applications that will work across all browsers [1].

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* WebVR API