Dev:Ref/Release Notes/2.79/Alembic

= Blender 2.79: Alembic =

The Alembic import & export has been improved, both in stability and compatibility (revisions ..)

Fixes

 * Fixed errors in matrix conversion (most Alembic files use Y=up, while Blender uses the more sensible Z=up).
 * Re-implemented part of the importer, so that it has to guess less, improving compatibility with non-Blender generated files (fixes T50403)
 * The importer is now more lenient to unknown types.
 * Improved performance by removing some unnecessary computations.
 * Prevented crash when cancelling import ( & ).
 * Fixed "flat" import (i.e. all objects in world coordinates, no parenting)
 * Fixed T50227: Alembic uv export/load issue
 * Added simple unit tests
 * Greatly improved performance of curve/hair import
 * Changing cache modifier path no longer discards object paths
 * Meshes with animation data are now saved on every frame (, T51351). This allows you to change a mesh procedurally, for example using a Python script, and have it exported every frame, simply by ensuring the mesh has some animation data on it.
 * Support for sub-frame sampling ( and ).
 * Fixed missing material assignment when an animated mesh changed vertex count.
 * Importing now takes the "inherit transform" flag into account correctly when constructing parent-child relationships ( and T52022).
 * Sequences of Alembic files are now handled properly ( and T51820).

New Features

 * Exporting of linked-in dupli-groups is now possible. This supports the common character animation workflow used at the Blender Institute, where a character, its rig, and the custom bone shapes are all part of a group. This group is then linked into the scene, the rig is proxified and animated. Such a group can now be exported. Use "Renderable objects only" in the export options to prevent writing the custom bone shapes to the Alembic file. (, T50688)
 * Exporting hair & particle systems is now optional. The export still takes more time with disabled hair than when there is no hair, as the particle systems themselves aren't disabled during the export. It's only the writing to the Alembic file that's skipped.
 * The Import and Export operators now take a new flag as_background_job, which is True by default. When set to False, the operator will block Blender during the import. This allows Blender scripts to perform tasks after the import/export has completed.
 * Empties can now also be exported to Alembic (both static and animated).
 * Exporting simple child hairs is now possible.
 * Added support for face-varying vertex colours (read: compatibility with Houdini) (, T51534)
 * Support for empty meshes (which can get vertices later in their animation) (, T51351)
 * Loading an Alembic file stored in the obsolete HDF5 format will now give an error message telling you the format is not supported in Blender (, T51292). Such files can be converted using AbcConvert. The current format, Ogawa, is 4x to 25x faster than HDF5, and was introduced almost four years ago.