Proposal: Fuzz/sheen can darken as well as lighten

I’d like to propose that it would be nice if the fuzz/sheen parameter was able to darken as well as lighten. Many surface appearances such as nylon stockings, denim jeans, and silk all appear darker on the glancing angle rather than lighter.

Offering this as a topic for discussion.

Begin by reviewing the fuzz/sheen parameter in the OpenPBR specification and reference implementation. Determine how darkening at glancing angles should be represented and define expected behavior for the cited materials. Done requires an agreed proposal plus corresponding specification and implementation changes.

Written by the indexing model from the issue text.