Hi!

I'm having a hard time unloading payloads via the Configure Stage node. I have a stage similar to the one in Houdini's USD Asset Building [www.sidefx.com] course, with a few changes - splitting the one payload into two: geo_payload and mtl_payload

Now the hierarchy looks like this:
HiRes_Pig (Kind: group)
|---geo_payload (Kind: component)
|---mtl_payload


I load in HiRes_Pig.usd via the Reference node,
and in a subsequent Configure Stage, I set Load Primitives to "Add and remove primitives to load", and:
a. Set Remove Load Paths from Input to /HiRes_Pig/geo_payload
or
b. %kind:component

If I understand the node documentation correctly, both of these should unload geo_payload. But they are unloading all the payloads.


I must be misusing this feature.. Please see the example file attached. Thanks!

USD lets a stage work in two modes: "load all payloads", or "load no payloads". In "load all payloads" mode, you cann't specify a list of payloads to _not_ load. But in "load no payloads" mode, you can specify a list of payloads to explicitly load. When you set the Configure Stage LOP to "Add and remove payloads to load", LOPs recreates the input stage in "load no payloads" mode, but allows you to control the explicit list of payloads to load.

So given this context, this means that "remove load paths" doesn't set a list of paths that should be unloaded (there is no such list). It removes the specified path from the list of paths that should be loaded. If that list starts out empty (load nothing), removing an entry from this empty list does nothing and you are still left with an empty list of paths that should load payloads. So no payloads load.

To get the result that (I think) you want, you must put "/HiRes_Pig/geo_payload /HiRes_Pig/mat_payload" in the "Load Paths", then you can remove "/HiRes_Pig/geo_payload" and get the result you expect. Or cut out the middle step and just put "/HiRes_Pig/mat_payload" in the "Load Paths" parameter.

@mtucker. That totally makes sense. I think I just confused the order of operation in Python with this workflow.
Looks like this is the correct way:


I want to ask a follow-up. I have a stage with nested payloads:


main_stage
|prototypes (payload)
|--sliu_sphere
|--|sliu_sphere_0
|--|--renderable (payload)
|--|sliu_sphere_1
|--|--renderable (payload)
...

Using the same method above, I first set nothing to load, so the stage looks like this at first:


Then, I start loading using primpattern "%nodescendants(%kind:group)". I expect that it would simply load prototypes, but not any of the payloads below. But everything got loaded, including the "renderables"

In the USD Python lib, I can achieve the desired behavior using the code snippet below:

I provided the example stage. Is there an equivalent to this in LOPs?

Solaris always does "load with descendants" style payload loading. We don't support "Load without descendants" because we found the implications of this workflow to be fairly confusing... You have to find the exact prim with the payload to load it. You can't just say "load everything from here down". Or if we were to provide both options (with or without descendants), we think that would result in a fairly complicated UI. So we went with the simplest thing that gives what we felt was the "most expected" behavior.

We also generally discourage nested payloads. They can complicate things and rarely provide a significant benefit. Especially in LOPs where we always do "Load with descendants".

Thanks for the insight! For the most part Solaris is faithful to all the features USD provides, but it makes sense why you're leaving this out.
Even though USD allows nested payloads, we also found it to "complicate things and rarely provide a significant benefit" as well 😄
That said, it would be nice to note this in the documentation. I had actually expected the Solaris behavior to be equivalent to "LoadWithoutDescendants"