Instead of keeping track of a local array of positions in the modifier
stack itself, use the existing edit mode SoA "edit cache" which already
contains a contiguous array of positions. Combined with positions as a
generic attribute, this means the state is contained just in the mesh
(and the geometry set) making the code much easier to follow.
To do this we make more use of the mesh wrapper system, where we can
pass a `Mesh` that's actually stored with a `BMesh` and the extra
cached array of positions. This also resolves some confusion-- it was
weird to have the mesh wrapper system for this purpose but not use it.
Since we always created a wrapped mesh in edit mode, there's no need
for `MOD_deform_mesh_eval_get` at all anymore. That function was quite
confusing with "eval" in its name when it really retrieved the original
mesh.
Many deform modifiers had placeholder edit mode evaluation functions.
Since these didn't do anything and since the priority is node-based
deformation now, I removed these. The case is documented more in the
modifier type struct callbacks.
Pull Request: https://projects.blender.org/blender/blender/pulls/108637
Some modifiers used `MOD_deform_mesh_eval_get` to make sure they had
a mesh to retrieve vertex groups from. But since curves don't support
vertex groups anyway, and since the curve to mesh conversion is handled
by the (legacy) curve object modifier stack anyway, this is confusing
and unnecessary. This shouldn't give any behavior changes, but some
deform modifiers on legacy curve objects might be faster if they used
to do the conversion.
A lot of files were missing copyright field in the header and
the Blender Foundation contributed to them in a sense of bug
fixing and general maintenance.
This change makes it explicit that those files are at least
partially copyrighted by the Blender Foundation.
Note that this does not make it so the Blender Foundation is
the only holder of the copyright in those files, and developers
who do not have a signed contract with the foundation still
hold the copyright as well.
Another aspect of this change is using SPDX format for the
header. We already used it for the license specification,
and now we state it for the copyright as well, following the
FAQ:
https://reuse.software/faq/
