I think Alembic file import is in need of an overhaul with regards to importing attributes. Some of the attributes just don’t import.
the main thing I was trying to do was import a model with 2 UV sets which didn’t work… but then I dug deeper and found out actually many more issues with attributes not importing
Not all custom attributes are supported specifically
custom vec3
custom string attributes
– are not supported
I think attributes which have the standard names such as [Cd] [mass] [force] [Alpha] [pscale][uv] these types are all supported types because these were grandfathered in from Houdini 4.0. and they are the “standard attributes” used often. But if you try to make your own custom named attribute called “uv_set2” or “foo” it won’t actually import.
Here is the kicker Bhclassic actually does support all these custom variable named attribute types. So we would like to have Alembic import attribute the same way that bhclassic imports attributes.
I’m guessing this is because TouchDesigner SOPS are basically written from Houdini version 4.0 SOPs when the two programs split and the attribute system for sops has not been updated since then, and Alembic is a newer file format so maybe the conversion wasn’t perfect the first pass.
Here is a side by side of the attributes in Houdini. Then the export of the alembic file which has a bunch of missing attributes, and the bhclassic which actually DOES import all the attributes.
Attached Alembic and bhclassic files here:
AlembicBhclassicAttributeTest.zip (28.6 KB)
This was tested on Windows build 2022.24200 and also 2021.16270 - but I am quite confident this has always been a problem with alembics and even doesn’t work with earlier versions wither.