This simplifies blend file handling, ensuring that blend files are only
opened once. Otherwise it would be harder to handle things like dependency
diamonds (libraries that are referenced via multiple paths through multiple
other libraries).
No path rewriting yet, just simply copying the dependencies. They are
copied to the target directory + the path relative to the current working
directory. For example:
bat pack scenes/05-barber/05_02_C-agent_focused/05_02_C.lighting.blend /tmp/packer
will write to
/tmp/packer/scenes/05-barber/05_02_C-agent_focused/05_02_C.lighting.blend
and will copy ./path/to/file → /tmp/packer/path/to/file
The expansion process follows pointers and library links to construct
the full set of actually-used data blocks. This set consists of all data
blocks in the initial blend file, and all *actually linked-to* data
blocks in linked blend files.
I've also removed non-recursive dependency listing.
Evaluated only once, so safe to call multiple times without producing
excessive disk I/O. Returns None instead of raising KeyError when there is
no (b'id', b'name') field.
