HIQaH! QaH! TAG!

I'm requesting a TAG review of the dynamic viewport scaling feature that's part of WebXR.

Applications can optionally render to a subset of the WebXR viewport, using a scale factor that can be changed every animation frame. This is intended to be more efficient than resizing the full framebuffer which requires reallocation, and the UA can supply a recommended scale factor based on internal heuristics.

• Explainer¹ (minimally containing user needs and example code): https://github.com/immersive-web/webxr/blob/master/explainer.md#dynamic-viewport-scaling
• Specification URL: This is part of the WebXR API. Relevant sections include requestViewportScale(), the internal attributes and the obtain a scaled viewport algorithm.
• Tests: https://github.com/web-platform-tests/wpt/blob/master/webxr/xr_viewport_scale.https.html and results
• Security and Privacy self-review²: https://github.com/klausw/webxr/blob/master/designdocs/dynamic-viewport-scaling-privacy-security.md
• GitHub repo (if you prefer feedback filed there): https://github.com/immersive-web/webxr/issues
• Primary contacts (and their relationship to the specification):
  • Brandon Jones (@toji) Google, Editor
  • Manish Goregaokar (@manishearth), Invited Expert (Mozilla until 2020), Editor
  • Klaus Weidner (@klausw), Google
• Organization(s)/project(s) driving the specification: Immersive-Web WG
• Key pieces of existing multi-stakeholder review or discussion of this specification: https://github.com/immersive-web/webxr/issues/1091
• External status/issue trackers for this specification (publicly visible, e.g. Chrome Status): https://www.chromestatus.com/feature/5640976515203072

Further details:

• I have reviewed the TAG's API Design Principles
• Relevant time constraints or deadlines: n/a
• The group where the work on this specification is currently being done: W3C Immersive Web
• The group where standardization of this work is intended to be done (if current group is a community group or other incubation venue): same
• Major unresolved issues with or opposition to this specification: n/a
• This work is being funded by: n/a

You should also know that...

This is an addition to the pre-existing WebXR specification editor's draft. TAG review was requested as part of blink-dev feedback.

There's strong developer interest in this feature including from <model-viewer> (see blink-dev thread above).

We'd prefer the TAG provide feedback as (please delete all but the desired option):

☂️ open a single issue in our GitHub repo for the entire review