Delay loading all DATA sections of the blend file until they're needed.
Loading all data-blocks caused high peak memory usage especially with
libraries - since a lot of data may exist which isn't used directly.
In one test (spring project: 10_010_A.anim.blend),
peaked at ~12.5gig, dropping back to ~2.5gig once loaded.
With this change peaks memory usage reaches ~2.7gig while loading.
Besides this there are some minor gains from not having to read data
from the file-system and we can skip an alloc + memcpy reading data
written with the same version of Blender.
Now that we are looping over all image users that were previously ignored,
it shows some scene pointers are invalid. Always clear them on load, and
don't keep scene permanently in the image user except for the image editor.
Otherwise the pointer can go out of date.
Do not instance linked object immediately in scene, this was never a
good idea and is doomed to fail nowadays, with complex relations between
objects, collections and scenes.
Instead, this commit refactors a bit linking code to add loose objects
to current scene *after* everything has been imported, and ID pointers
have been properly remapped to new ones - i.e. once new linked data is
supposed to be fully valid, just like we were already doing with
collections.
As a bonus, it means we do not have to pass around scene, view3d etc. to
`BLO_library_link_named_part_ex()` and co.
We may want to use 'TEST' BCode in the future for including data
besides thumbnails. This allows negative values to be used w/o
attempting to load a thumbnail.
When one is indirectly linking collections, better add collection to the
scene, than instantiating its objects into master collection of the
scene. That is much cleaner.
Noted/related to T61141.
Yes, we do can undo an ID deletion now.
However, this requires extra care in UI 'remapping' to new IDs step
(when undoing, we do not fully reload the UI from saved .blend).
Otherwise, new UI (i.e. one from saved .blend file) might reference
IDs that where freed in old bmain (the one before the undo), we cannot
use those to get ID name then, that would be a nasty use-after-free!
To prevent this, we generate a GSet of all valid ID pointers at that
time (i.e. those found in both old and new Main's), and ensure any ID
we try to remap by its name is in that GSet. Otherwise, there is no
possible remapping, just return NULL.
BF-admins agree to remove header information that isn't useful,
to reduce noise.
- BEGIN/END license blocks
Developers should add non license comments as separate comment blocks.
No need for separator text.
- Contributors
This is often invalid, outdated or misleading
especially when splitting files.
It's more useful to git-blame to find out who has developed the code.
See P901 for script to perform these edits.
BF-admins agree to remove header information that isn't useful,
to reduce noise.
- BEGIN/END license blocks
Developers should add non license comments as separate comment blocks.
No need for separator text.
- Contributors
This is often invalid, outdated or misleading
especially when splitting files.
It's more useful to git-blame to find out who has developed the code.
See P901 for script to perform these edits.
