Intent to Prototype: XRPose Motion APIs

[Alex Cooper]

Contact emails

alco...@chromium.org, bia...@chromium.org

Explainer

None

Specification

https://immersive-web.github.io/webxr/#dom-xrpose-linearvelocity

Summary

Allows querying for the linear acceleration and linear velocity on an XRPose if the underlying runtime supports providing this information.

Blink component

Blink>WebXR

Motivation

Initial public proposal

TAG review

https://github.com/w3ctag/design-reviews/issues/545

https://github.com/w3c/transitions/issues/420

TAG review status

Issues addressed

Risks

Interoperability and Compatibility

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

WebKit: No signal

Web developers: No signals

Other signals:

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?

Debuggability

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

No; tests not yet written.

Flag name

Requires code in //chrome?

False

Tracking bug

https://crbug.com/1377436

Estimated milestones

No milestones specified

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5984008124497920

This intent message was generated by Chrome Platform Status.

[Mike Taylor]

On 3/23/23 6:21 PM, 'Alex Cooper' via blink-dev wrote:

Contact emails

alco...@chromium.org, bia...@chromium.org

Explainer

None

Specification

https://immersive-web.github.io/webxr/#dom-xrpose-linearvelocity

Summary

Allows querying for the linear acceleration and linear velocity on an XRPose if the underlying runtime supports providing this information.

As someone who doesn't work in the XR space, can you explain how this is useful for developers, i.e., what kind of use cases does this unlock?

Blink component

Blink>WebXR

Motivation

Initial public proposal

TAG review

https://github.com/w3ctag/design-reviews/issues/545

https://github.com/w3c/transitions/issues/420

TAG review status

Issues addressed

Risks

Interoperability and Compatibility

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

WebKit: No signal

Now would be a good time to request a position from WebKit (so they have plenty of time to respond): https://github.com/WebKit/standards-positions

Web developers: No signals

Other signals:

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?

Debuggability

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

No; tests not yet written.

Flag name

Requires code in //chrome?

False

Tracking bug

https://crbug.com/1377436

Estimated milestones

No milestones specified

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5984008124497920

This intent message was generated by Chrome Platform Status.

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[Rik Cabanier]

>
> Specification
>
> https://immersive-web.github.io/webxr/#dom-xrpose-linearvelocity
>
> Summary
>
> Allows querying for the linear acceleration and linear velocity on an XRPose if the underlying runtime supports providing this information.

Alex, did you mean to say angular and linear velocity?

> As someone who doesn't work in the XR space, can you explain how this is useful for developers, i.e., what kind of use cases does this unlock?

Very often in AR/VR experiences, you would like to know the linear and
angular velocity of an object so you know how it interacts with the
virtual world
For instance, if you hit a tennis ball with your hand/controller, its
following speed and trajectory will depend on the speed of your
controller. For a curve ball, you can use the angular velocity to
calculate its spin.

An XR experience can make a rough estimation of this by keeping track
of the position of the controller over time but it's not very precise
especially for angular velocity. Controllers have built-in
accelerometers that will give you precise tracking. The runtime will
also "timewarp" the velocities so they apply to the point in time that
the current frame is shown.

You can find a more detailed explanation in the issue:
https://github.com/immersive-web/webxr/issues/619

[Mike Taylor]

Thank you - super useful.

[Alex Cooper]

>> Allows querying for the linear acceleration and linear velocity on an XRPose if the underlying runtime supports providing this information.

> Alex, did you mean to say angular and linear velocity?

Ah, yes. So I did. And thanks for the reply with the usefulness Rik!

 

> Now would be a good time to request a position from WebKit (so they have plenty of time to respond): https://github.com/WebKit/standards-positions

My intention here FWIW is to ask WebKit about the full WebXR spec, since some of the work we're working towards is matching the CR recommendation even if we are availing ourselves of the (specced) options to not return data at the moment.