The main idea is to switch Bake from Multires from legacy DerivedMesh
to Subdiv. On the development side of things this change removes a lot
of code, also making it easier easier to rework CustomData and related
topics, without being pulled down by the DerivedMesh.
On the user level switch to Subdiv means:
- Much more closer handling of the multi-resolution data: the derived
mesh code was close, but not exactly the same when it comes to the
final look of mesh.
Other than less obvious cases (like old DerivedMesh approach doing
recursive subdivision instead of pushing subdivided vertices on the
limit surface) there are more obvious ones like difference in edge
creases, and non-supported vertex creases by the DerivedMesh.
- UV interpolation is done correctly now when baking to non-base level
(baking to multi-resolution level >= 1).
Previously in this case the old derived mesh interpolation was used
to interpolate face-varying data, which gives different results from
the OpenSubdiv interpolation.
- Ngon faces are properly supported now.
A possible remaining issue is the fact that getting normal from CCG
always uses smooth interpolation. Based on the code it always has been
the case, so while it is something to look into it might be considered
a separate topic to dig into.
In order to better interop with the broader Alembic/USD ecosystem, align
the crease values we export with what we believe is expected by native
OpenSubdiv, a 0-10 range.
On import we will translate the native OpenSubdiv range back into
Blender's 0-1 range.
To account for SubD assets produced by Blender before this change, a
compat check is put in place for both Alembic and USD to use the old
methodology when encountering such files. The compat check makes use
of the Blender version we place inside the format's metadata fields. Old
assets loaded into a new Blender will look ok. New assets loaded into an
old Blender would need to be reworked.
Pull Request: https://projects.blender.org/blender/blender/pulls/132582
Move most code to `blender::bke::subdiv`. That helps organization
and makes using C++ in subdiv code easier, which will be useful for
removing the unnecessary opensubdiv C-API wrapper.
Listing the "Blender Foundation" as copyright holder implied the Blender
Foundation holds copyright to files which may include work from many
developers.
While keeping copyright on headers makes sense for isolated libraries,
Blender's own code may be refactored or moved between files in a way
that makes the per file copyright holders less meaningful.
Copyright references to the "Blender Foundation" have been replaced with
"Blender Authors", with the exception of `./extern/` since these this
contains libraries which are more isolated, any changed to license
headers there can be handled on a case-by-case basis.
Some directories in `./intern/` have also been excluded:
- `./intern/cycles/` it's own `AUTHORS` file is planned.
- `./intern/opensubdiv/`.
An "AUTHORS" file has been added, using the chromium projects authors
file as a template.
Design task: #110784
Ref !110783.
