XRPermissionDescriptor.optionalFeatures

Secure context
This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The XRPermissionDescriptor dictionary's optionalFeatures property is used to specify a list of WebXR features which your app or site would like to use but can operate without if permission isn't granted to use them.

Syntax

xrPermissionDescriptor = {
   mode: xrSessionMode,
   requiredFeatures: reqFeatureList,
   optionalFeatures: optFeatureList
};

xrPermissionDescriptor.optionalFeatures = optFeatureList;
optFeatureList = xrPermissionDescriptor.optionalFeatures;

Value

An array of strings taken from the XRReferenceSpaceType enumerated type, indicating set of features that your app would like to use, but can operate without if permission to use them isn't available. While further features may be defined in future editions of WebXR, currently all permitted values come from the XRReferenceSpaceType enumerated type, indicating reference spaces the app rquires to be available.

The reference space returned by XRSession.requestReferenceSpace() is either XRReferenceSpace or XRBoundedReferenceSpace. The "Interface" column in the table below indicates which of the two types is returned for each reference space type constant..

Reference space descriptors

The types of reference space are listed in the table below, with brief information about their use cases and which interface is used to implement them.

XRReferenceSpaceType Description Interface
bounded-floor Similar to the local type, except the user is not expected to move outside a predetermined boundary, given by the boundsGeometry in the returned object. XRBoundedReferenceSpace
local

A tracking space whose native origin is located near the viewer's position at the time the session was created. The exact position depends on the underlying platform and implementation. The user isn't expected to move much if at all beyond their starting position, and tracking is optimized for this use case.

For devices with six degrees of freedom (6DoF) tracking, the local reference space tries to keep the origin stable relative to the environment.

XRReferenceSpace
local-floor Similar to the local type, except the starting position is placed in a safe location for the viewer to stand, where the value of the y axis is 0 at floor level. If that floor level isn't known, the user agent will estimate the floor level. If the estimated floor level is non-zero, the browser is expected to round it such a way as to avoid fingerprinting (likely to the nearest centimeter). XRReferenceSpace
unbounded A tracking space which allows the user total freedom of movement, possibly over extremely long distances from their origin point. The viewer isn't tracked at all; tracking is optimized for stability around the user's current position, so the native origin may drift as needed to accommodate that need. XRReferenceSpace
viewer A tracking space whose native origin tracks the viewer's position and orientation. This is used for environments in which the user can physically move around, and is supported by all instances of XRSession, both immersive and inline, though it's most useful for inline sessions. It's particularly useful when determining the distance between the viewer and an input, or when working with offset spaces. Otherwise, typically, one of the other reference space types will be used more often. XRReferenceSpace

Usage notes

Examples

let xrPermissionDesc = {
  name: "xr",
  mode: "immersive-vr",
  optionalFeatures: [ "bounded-floor" ]
};

if (navigator.permissions) {
  navigator.permissions.query(xrPermissionDesc).then(({state}) => {
    switch(state) {
      case "granted":
        setupXR();
        break;
      case "prompt":
        promptAndSetupXR();
        break;
      default:
        /* do nothing otherwise */
       break;
  }
  .catch(err) {
    console.log(err);
  }
} else {
  setupXR();
}

Specifications

Specification Status Comment
WebXR Device API
The definition of 'XRPermissionDescriptor.optionalFeatures' in that specification.
Working Draft Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
optionalFeaturesChrome No support NoEdge No support NoFirefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android No support NoFirefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android No support No

Legend

No support  
No support

See also