I imported an Alembic file with different Face IDs to Houdini. But when I export it back via Alembic. The Face IDs are fine, but randomly distributed? I cannot see any pattern. It's neither alphabetically nor based on face count. My node tree consists of: Alembic Import Node –> Unpack –> ROP Alembic Output.
yes of course! I am using 3ds Max' Multi Sub Object Material.
On the left side you see the original mesh with correct Material ID order and on the right side the imported Mesh with the wrong material order. The grouping is basically right, but they dont't have the correct order/ID…
It looks like 3ds Max cares about the order facesets are defined instead of identifying them by name.
Facesets are represented in Houdini as primitive groups. However, Houdini's geometry model does not preserve the ordering of groups so the ordering is lost and it looks like this confuses 3ds Max.
We made a change to the Alembic ROP in Houdini 16.0.696 so it will create facesets in sorted order. We think they should now be exported with an ordering that 3ds Max expects.
thank you very much! I'll try it out for the next project, when there is a production build - because for the current project I found a workaround.
My current workflow is to merge the whole building in order to create one MultiSubMaterial then splitting the Mesh by its material IDs by a script. All faces with ID 1 are named: 001 All faces with ID 2 are named: 002 All faces with ID 3 are named: 003 and so on….
After importing the .abc file as “Unpack Alembic Delayed Load Primitives” in Houdini I can see the prim groups named 001, 002, 003,… Then I export it and everything is in the correct order. But however this is kind of a hacky way…
