Rigid Alembic Caches: Velocity, UVs and POINT NUMBER!

[ben.fox@framestore.com]

I tried multiple versions of the shatter build...because there is a chance of getting separate faces like you got in the file I uploaded.
I thought I was on to something with that and spent a good chunk of time trying to get the cleanest possible shatter...but all ended up the same.
My final test was merging 10 Houdini Boxes. All were totally basic clean triangulated boxes and it still comes in as a single object as multibody...and it gets multiplied when I read the same SD back into Houdini. It definitely seems like something is wonky with the exporter.
Let me know what you find out from the Houdini Plugin devs.
Thanks for all the hard work!
~Ben

[gus]

Hi Ben,

I think I know where the problem might be.
From what you say, it looks to me that we might be expecting multiple transforms in the import multibody operation, and you are just providing a single object, kinda trying to import a multibody as a multibody.
Do you know what I mean?
If all your fractured pieces had their own transform node inside Houdini, and you use the sd exporter, I'd say you will be getting the "correct" multibody import, with all of them appearing in the Summary Info.
If this is what you are trying to do, we probably will have to review our import options and see if there are other ways of loading this kind of data.

The duplicates still seem to me a bug in the plugin though

Thanks for all this testing and feedback. Much appreciated.

g-)

[ben.fox@framestore.com]

Yeah, that is the root of the issue.
Houdini really doesn't need transforms for most of the stuff you do.
Needing to separate transforms for every piece of a shattered mesh would make the benefits of exporting to Realflow really hard to sell.
Everything would be fine if Houdini's Alembic Exporter didn't have the issue with partitioning meshes. A partitioned Alembic came into Realflow fine and simmed as a multibody.
I am sure your list is long, perhaps this would be something to address in the Houdini exporter at some point.
Thanks for looking into it.
~Ben

[gus]

Ok.

Maybe we could talk to Sidefx about that issue with the Alembic partitioning. Perhaps it might be the fastest way to get it fixed. We had talk in the past about using .bgeo inside RF, but since Alembic came out it seems pointless to have so many file formats doing the same.

g-)

[ben.fox@framestore.com]

Alright, I have made some progress on this.
So it seems the bug is not consistant with Houdini's Alembic export partitioning.
It is closer to the realm now of 'something to look out for' instead on unfixable bug. With a little cleanup you can make a shattered mesh and use Houdini's Alembic partition attribute with consistency. Annoying but workable.

So things are close, I have an Alembic multibody in Realflow and all looks promising.
Now, the issue is just with resetting.
I import the Alembic as a multibody and sim it and then hit reset and it doesn't reset.
Any thoughts?
~Ben

[gus]

Hi Ben,

Definitely a bug. Just reproduced it here

Thanks for reporting it.

g-)