Two were actual bugs, though they existed only in unused code:
* In Freestyle it was unintentionally copying a scene rather than referencing it.
* In BLI_array_store_is_valid there was use of uninitialized memory.
This commit changes a lot of how IDs are handled internally, especially the unlinking/freeing
processes. So far, this was very fuzy, to summarize cleanly deleting or replacing a datablock
was pretty much impossible, except for a few special cases.
Also, unlinking was handled by each datatype, in a rather messy and prone-to-errors way (quite
a few ID usages were missed or wrongly handled that way).
One of the main goal of id-remap branch was to cleanup this, and fatorize ID links handling
by using library_query utils to allow generic handling of those, which is now the case
(now, generic ID links handling is only "knwon" from readfile.c and library_query.c).
This commit also adds backends to allow live replacement and deletion of datablocks in Blender
(so-called 'remapping' process, where we replace all usages of a given ID pointer by a new one,
or NULL one in case of unlinking).
This will allow nice new features, like ability to easily reload or relocate libraries, real immediate
deletion of datablocks in blender, replacement of one datablock by another, etc.
Some of those are for next commits.
A word of warning: this commit is highly risky, because it affects potentially a lot in Blender core.
Though it was tested rather deeply, being totally impossible to check all possible ID usage cases,
it's likely there are some remaining issues and bugs in new code... Please report them! ;)
Review task: D2027 (https://developer.blender.org/D2027).
Reviewed by campbellbarton, thanks a bunch.
Previously a whole mesh was stored between undo steps,
This commit uses BLI_array_store to de-duplicate memory use between undo steps.
Memory saving depends entirely on kinds of edits performed,
in own tests 5x-15x less memory use is common.
Compacting the memory does give some overhead however its done in a background thread
so its not blocking in most cases.
New behavior and threading can be ifdef'd out to check for regressions.
See D2026 for details.
