2016-11-7, Alembic 1.7.0
Hello Alembic users,
Thanks to your feedback we are introducing the new layering functionality to Alembic, as discussed here:
https://groups.google.com/forum/#!topic/alembic-discussion/s0zm8VEBMOk
AbcCoreLayer was developed collaboratively between Blizzard Entertainment and Sony Pictures Imageworks and is a way for you make sparse changes to an Alembic file by writing those changes into any number of other Alembic files, and combining them on read via AbcCoreLayer.
Here are some examples of what you can do via layering:
You can add additional properties to a shape.
Example: Adding UVs to a polymesh that currently lack them
You can override properties.
Example: Override static points on a polymesh with animated points.
You can add new objects.
Example: Add a shape to an existing hierarchy.
You can prune objects.
Example: Remove shapes you don't like, or entire branches of the hierarchy.
You can prune properties.
Example: Removing incorrect normals.
You can replace an object hierarchy with a different one.
Example: You can replace separate curves groups with one big one.
You can replace property hierarchy.
Example: Don't like a bunch of properties in user properties? It can be replaced with a bunch of other properties, without needing to prune individual properties.
AbcCoreLayer provides a SetPrune and SetReplace convenience function in Util.h, for setting up the MetaData appropriately.
Maya:
AbcImport: Support AbcCoreLayer by specifying more than one file to the AbcImport command.
AbcExport:
Support writing only UVs via -uvsonly or -uvo flag.
Utilities:
AbcDiff: Given 2 Alembic files, create a sparse diff between them.
Other changes:
API:
Internally keep track of how many bytes we've written to reduce the number of potentially expensive calls on write.
Harden some unnecessary templated constructors in Abc and AbcGeom.
Deprecate (but do not remove) constructors that take the kWrapExisting and kTop flag and provide reasonable constructors that don't use these flags in Abc and AbcGeom.