Proposal: UI Hints in USD

Hi all,

I’ve just posted a PR proposal for expanding presentation metadata (aka UI hints) support in USD. Things like specifying a particular widget type for use when displaying an attribute, min/max values that numeric fields can enforce, and expressions defining dynamic hiddenness for attributes and display groups.

PR here
Rendered view here

Feedback welcome in this thread, or on the PR directly.

Thanks!
Allison

I just updated the proposal with our latest thinking, for anyone who’s following along:

* Removed reference to the locked hint, which will be addressed separately
* Added more detail to the limits discussion section
* Added arraySizeConstraint discussion section
* Noted deferral of widgetType and widgetOptions implementation

The big takeaway is the deferral on implementing widgetType and widgetOptions, for now. Some concerns have been raised in particular about them being open-ended and what that means for DCC vendors. We want to return to these fields in the future and make sure they’re fully baked, but in the meantime we don’t want to hold up implementation of the other fields.

The arraySizeConstraint core field, newly added to the proposal, will replace the array-related widget options that had been described in the proposal.

The updated rendered view is here.