Blender Git Commits

Changed implementation of the Cache modifier to work in tandem with the
cache library system.

The Cache modifier is now an optional "break point" of the modifier
stack:
- Without a cache modifier the stack works as before. Baking will write
the final stack result. After baking the cache replaces the whole
stack.
- With a cache modifier the stack result at the modifier's position is
stored. The cache is then applied as the output of that modifier,
skipping preceding modifiers. That way additional modifiers can be
applied on top of the cache.
- When using multiple cache modifiers, only the last (active) one will
be used, since all previous cache results would be discarded anyway.

Replaced point cache in cloth modifiers (also hair) with the new caching
system.

Conflicts:
source/blender/blenkernel/intern/cloth.c

'expand' function for cache libraries, so link/append makes it load the
group and objects too.

Make cache libraries a linkable data block.

Take NULL object pointers in cache items into account.

This can happen if an object gets deleted or isn't loaded for some
reason. The item should just be ignored in that case and removed at the
next opportunity (cleanup function).

When using the "new cache library" operator, enable fake user by
default.

Nothing actually links to a cache library at this point (and probably
won't in the future), so fake user is necessary to avoid losing data.

Display cache library name and fake user button, imitating template_ID.

Importing of caches into Blender data.

Currently only implemented for DerivedMesh.
This replaces the `final_dm` calculation of the modifier stack with the
result from cache loading.

UI fixes, draw bake operator button only once at the top.

Hair path writer needs 2 different variants for parent/child hairs.

Added writers for derived mesh result and hair paths.

Use explicit name strings for all readers/writers in the cache instead
of constructing names internally.

This helps prevent name collisions and guarantees a consistent naming
scheme for putting multiple items in the same cache.

New reader/writer for DerivedMesh.

Used as a base for existing PointCacheModifier classes, but can be used
on its own.

General support for export to/import from Alembic files based on Cache
Libraries.

Deleted unimplemented parts of the previous pointcache system, to make
refactoring simpler.

Since the new approach is not tied to the old set of point cache data
types there is really no need to carry their empty husks around. Once
the new caching system is defined in detail we can add back whatever
makes sense.

Disabled specialized Point Cache modifier handling in the modifier
stack, this will be replaced and is not correct anyway.

Refactoring of archive handling in readers/writers.

Now instead of each reader/writer creating its own archive, the archive
is created by the caller in advance and passed as a constructor
argument. This means that multiple items can be stored together in the
same archive.

Removed unused Scene pointer from the base Reader/Writer classes.

Operator skeleton for a cache bake operator, using the job system.

Fix for undefined return value.