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.
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/
This integrates the new implicit-sharing system (from fbcddfcd68)
with `CustomData`. Now the potentially long arrays referenced by custom
data layers can be shared between different systems but most importantly
between different geometries. This makes e.g. copying a mesh much cheaper
because none of the attributes has to be copied. Only when an attribute
is modified does it have to be copied.
Also see the original design task: #95845.
This reduces memory and improves performance by avoiding unnecessary
data copies. For example, the used memory after loading a highly
subdivided mesh is reduced from 2.4GB to 1.79GB. This is about 25%
less which is the expected amount because in `main` there are 4 copies
of the data:
1. The original data which is allocated when the file is loaded.
2. The copy for the depsgraph allocated during depsgraph evaluation.
3. The copy for the undo system allocated when the first undo step is
created right after loading the file.
4. GPU buffers allocated for drawing.
This patch only gets rid of copy number 2 for the depsgraph. In theory
the other copies can be removed as part of follow up PRs as well though.
-----
The patch has three main components:
* Slightly modified `CustomData` API to make it work better with implicit
sharing:
* `CD_REFERENCE` and `CD_DUPLICATE` have been removed because they are
meaningless when implicit-sharing is used.
* `CD_ASSIGN` has been removed as well because it's not an allocation
type anyway. The functionality of using existing arrays as custom
data layers has not been removed though.
* This can still be done with `CustomData_add_layer_with_data` which
also has a new argument that allows passing in information about
whether the array is shared.
* `CD_FLAG_NOFREE` has been removed because it's no longer necessary. It
only existed because of `CD_REFERENCE`.
* `CustomData_copy` and `CustomData_merge` have been split up into a
functions that do copy the actual attribute values and those that do
not. The latter functions now have the `_layout` suffix
(e.g. `CustomData_copy_layout`).
* Changes in `customdata.cc` to make it actually use implicit-sharing.
* Changes in various other files to adapt to the changes in `BKE_customdata.h`.
Pull Request: https://projects.blender.org/blender/blender/pulls/106228
