[Bf-usd] Blender Collections & USD

[Brian Savery]

Hi Brecht, et all.

I've been meaning to write up a bit more here (too many projects), but I'd
like to give an idea what we (AMD) are working on, because it overlaps a
bit with what you lay out in that document.  A lot of what you say would be
good to do inside Blender, however we have already done quite a bit of this
in an addon!

So basically, our WIP addon is two things:
1.  A Hydra render addon to blender (just like any other renderer addon)
that renders via hydra similar to other renderer plugins to Blender.  We of
course include the Radeon ProRender Hydra delegate but you could use this
with PRMan Hydra delegate, or Redshift, or Octane, or Arnold etc.  So think
of this like a "meta" render addon.  Part of the motivation here actually
was because we felt that each render addon to blender is kinda replicating
the same code to export data to the renderer and USD Hydra gives a good
abstraction layer for this.

2.  So the normal way a renderer addon works is to pull data directly from
Blender.  We also include a USD Node graph, which allows you to composite
USD via references, export data from blender into the USD node graph,
filter data etc.  The Hydra render addon would then pull from the nodegraph
rather than data directly from blender and get the references etc.  I added
some screenshots and discussion here:
https://devtalk.blender.org/t/a-out-the-tangent-animation-meeting-a-proper-place-to-talk-about-it/13733/3?u=bsavery

So rather than being a direct property of collections we achieve this in a
node graph for assembling the data.

We're pretty close to sharing something for testing and feedback from
users, certainly we are hoping early fall.  In the meantime if there are
serious objections or thoughts on this approach we'd like to hear them.

Finally here's a bunch of issues we are hitting so far.

1.  Distribution.  Blender statically links in USD dll's which is less than
idea as we need to include our own then for this.
2. Furthermore, it would be ideal to get a pointer to USD data exported
from the USD export function rather than exporting our own USD data
3.  Namespace issues on macOS don't allow us to currently bring in separate
USD dlls

Of course IMO this is something that could be even more powerful built into
blender, with a built in hydra rendering option.  Perhaps after we get this
addon out there that can be visited, but I think we're much closer to
getting this out as an addon.

Brian


>
> Hi all,
>
> I've written a design doc about how USD might integrate more closely in
> Blender, and how that would relate to collections and other Blender data
> structures.
> https://developer.blender.org/T68933
>
> It's only a rough proposal at this point, and we'll discuss this more
> internally as well. But it would be great to hear feedback and see if the
> overall direction makes sense to others.
>
> Regards,
> Brecht.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.blender.org/pipermail/bf-usd/attachments/20200811/d2213d45/attachment.htm>