Apologies—an update is long overdue!
The good news is that writing the text and making figures is finally basically done, save for one section that should be finished very soon. The 4th edition of the book will be published by the MIT Press; they have been great to work with so far and we’re confident that they will be a good partner in producing a quality product. The production pipeline (layout, copyediting, proofreading, indexing, …) will take a few months and then there’s the time to print the thing and ship the books. Spring 2022 for physical books seems like it’s in the right zone, but we don’t have a date set yet.
The other piece of good news is that MIT Press has agreed that we can continue to offer the book’s contents freely online on the website. (This was an important detail from our side in coming to agreement with them!) It is not yet decided when that will go live, or even whether it will be before or after the book is printed. More updates as that becomes clear.
As far as helping: at this point I think we are (finally) in good shape on the text (et al.) Giving pbrt-v4 a whirl and reporting bugs is definitely helpful, especially insofar as those are things that correspond to bugs in the book proper (but all sorts of bugs are good to know about.) Also, for anyone familiar with OptiX, it would be nice to start using OptiX’s animated transform support and curve primitive; that’s still not wired up on the pbrt-v4 side, since that’s not discussed in the book (continuing our pattern of not discussing pbrt’s use of third-party APIs in the text.)
Thanks,
Matt