Intent to Ship: XRVisibilityMaskChange

[Chromestatus]

Contact emails

alco...@chromium.org

Specification

https://immersive-web.github.io/webxr/#xrvisibilitymaskchangeevent-interface

Summary

Adds an XRVisibilityMaskChange event that will provide a list of vertices and a list of indices to represent the mesh of the visible portion of the user's viewport. This data can then be used to confidently limit the amount of the viewport drawn to in order to improve performance. To better support this event, XRView's are also given unique identifiers to allow easier pairing with the associated masks. This is an extension to the core WebXR specification.

Blink component

Blink>WebXR

Web Feature ID

webxr-device

Motivation

Without this change, pages are forced to draw to the full texture provided for the corresponding viewport, when portions of this viewport will not even be visible to the user, resulting in wasted work. By providing an event to describe the clipped-to area of the viewport, developers can save on per-frame work, and improve performance of their experiences, by reducing the required fill rate by 5-10% depending on device. This is given as an event because some system-level functionality may in fact capture the entire viewport, and thus those systems would like to toggle between having developers draw the entire viewport versus only the area visible to the active user.

Initial public proposal

No information provided

TAG review

No information provided

TAG review status

Not applicable

Risks

Interoperability and Compatibility

No information provided

Gecko: Positive (https://github.com/mozilla/standards-positions/issues/218)

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/155) Note that the Apple Vision Pro does ship WebXR behind a flag.

Web developers: Positive Note that Meta has a pending change to merge into one of the popular WebXR libraries pending this shipping in other browsers.

Other signals: The feature was proposed by Meta, who I believe has this implemented in the Quest browser.

Ergonomics

This is an event that is fired with a typically smallish amount of data, but also expected to only be triggered infrequently. The feature itself is designed to help developers improve performance of their experiences by reducing needless work.

Activation

The structure of the event is designed to cleanly work with clipping logic within glsl, and developers from Meta already have draft changes to merge into THREE.js, a popular WebXR library to take advantage of this.

Security

N/a

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

Feature is not exposed on WebView

Debuggability

No information provided

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

No
WebXR is not supported on WebView. Sessions are really only possible on Windows and Android, but types are not blocked on other Desktop platforms.

Is this feature fully tested by web-platform-tests?

Yes
https://wpt.fyi/results/webxr?label=experimental&label=master&aligned Note that tests *do* run on the CQ. Results on wpt.fyi are blocked by crbug.com/410607164

Flag name on about://flags

No information provided

Finch feature name

WebXRVisibilityMask

Rollout plan

Will ship enabled for all users

Requires code in //chrome?

False

Tracking bug

https://issues.chromium.org/issues/450538226

Availability expectation

Feature should be available on Meta Quest browser either now or soon.

Estimated milestones

Shipping on desktop	144
Shipping on Android	144

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

None expected

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5073760055066624?gate=6599862548299776

This intent message was generated by Chrome Platform Status.