The depsgraph was always created within a fixed evaluation context. Passing
both risks the depsgraph and evaluation context not matching, and it
complicates the Python API where we'd have to expose both which is not so
easy to understand.
This also removes the global evaluation context in main, which assumed there
to be a single active scene and view layer.
Differential Revision: https://developer.blender.org/D3152
- Only basis balls are exported, as they represent the resulting mesh.
As a result the mesh is written to Alembic using the name of the basis
ball.
- MetaBalls are converted to a mesh on every frame, then an
AbcMeshWriter is used to write that mesh to Alembic.
When the mesh changed topology but kept the vertex count the same, it would
result in a corrupt mesh. By checking the face & loop counts too, this has
become less likely.
I've checked IPolyMeshSchema::isConstant(), but it returns true even when
we see that the mesh changed topology.
When a mesh changes its number of vertices during the animation,
Blender rebuilds the DerivedMesh, after which the materials weren't
applied any more (causing the default to the first material slot).
Note that some little parts of code have been dissabled because eval_ctx
was not available there. This should be resolved once DerivedMesh is
replaced.
This allows you to put any kind of animation data on the mesh, and its
shape will be exported on each timekey. Note that this timekey is unrelated
to the animation data (so we don't export on each keyframe, for example).
A practical example is the addition of an animated custom property to
trigger the export of animated mesh data. The mesh data can then be created
from any source, like Python scripts.
Not only is this useful in itself, it also provides a workaround for one
of the two issues described in T51351.
No longer passing time as float and constructing ISampleSelectors all
over the place. Instead, just construct an ISampleSelector once and
pass it along.
With the new names the arguments (yup, zup) are in the same order as
they appear in the function name. The old names used copy_src_dst(dst,
src), which I found very confusing. Furthermore, now it is clear from
where to where the copy is made.
This makes the function names a little bit longer, though. If that is
a real issue, we can just name them zup_from_yup(zup, yup).
Reviewed by: Kévin Dietrich
Most of them are harmless implicit conversions (e.g. Alembic deals with
doubles for storing time information when Blender uses both ints and
floats/doubles) or class/struct mismatch on forward declarations.
Crash is due by mismatching loops and faces counts between the Alembic
data and the Blender derivedmesh which does not appear so
straightforward to fix (the crash happens deep in the derivedmesh code).
So for now, try to detect if the topology has changed and if so, both
only read vertices (vertex colors and UVs won't be read, as tied to face
loops) and add a warning message in the modifier's UI to let the user
know.
constraints.
This avoids traversing the archive everytime object data is needed and
gives an overall consistent ~2x speedup here with files containing
between 136 and 500 Alembic objects. Also this somewhat nicely de-
duplicates code between data creation (upon import) and data streaming
(modifiers and constraints).
The only worying part is what happens when a CacheFile is deleted and/or
has its path changed. For now, we traverse the whole scene and for each
object using the CacheFile we free the pointer and NULL-ify it (see
BKE_cachefile_clean), but at some point this should be re-considered and
make use of the dependency graph.
This would cause Alembic to throw an exception and fail exporting
animations because it was trying to recreate and overwrite the
attributes for each frame.
All in all, this patch adds an Alembic importer, an Alembic exporter,
and a new CacheFile data block which, for now, wraps around an Alembic
archive. This data block is made available through a new modifier ("Mesh
Sequence Cache") as well as a new constraint ("Transform Cache") to
somewhat properly support respectively geometric and transformation data
streaming from alembic caches.
A more in-depth documentation is to be found on the wiki, as well as a
guide to compile alembic: https://wiki.blender.org/index.php/
User:Kevindietrich/AlembicBasicIo.
Many thanks to everyone involved in this little project, and huge shout
out to "cgstrive" for the thorough testings with Maya, 3ds Max, Houdini
and Realflow as well as @fjuhec, @jensverwiebe and @jasperge for the
custom builds and compile fixes.
Reviewers: sergey, campbellbarton, mont29
Reviewed By: sergey, campbellbarton, mont29
Differential Revision: https://developer.blender.org/D2060
