Exporting unshared proxyshapes?

[pierre-ed]

Hi everyone,

Quick question.
(Apologies if it is a duplicate.)

We are currently attempting to move from v0.27.0 to v0.32.0, and we noticed a behavioral change that is quite dramatic for us: namely, the fact that proxyshapes whose their root layer is anonymous cannot be exported anymore (at least using cmds.mayaUSDExport()).
This difference seems to have been introduced in v0.30.0, in an effort to export stages as references.

This is quite alarming for us as we mostly manipulate unshared proxyshapes in our scenes (therefore their root layer is made internally anonymous) and up until now, we heavily relied on a custom export chaser to serialize their session layer at specific locations on disk.

As it stands, all our exports are now dead in the water, and as it represents a huge part of our workflows, I'd love to limit changes to what is strictly required.

Is there any workaround to still trigger the export of unshared proxyshape nodes, or have them be processed by a registered export chaser?
Any advice is welcome.
Thank you in advance.

Cheers,
Pierre.

[wallworm]

Thanks for the discussion. We will discuss a plan to address your use case.

For clarification, you would like us to write an Xform for the proxyshape when the root is anonymous?

[wallworm]

Have you tried to turn off the option to export the proxyshapes as references? Will this fix your issue?

[pierre-ed]

Hi Shawn and thank you for your answer.

Yes.
Ideally for us, any proxyshape should be present as a Xform in the output layer, and our custom export chaser plugin should be able to handle the rest from there.

Up to this point, it was our chaser that took upon itself to add the reference to the unshared proxyshape's "actual" root layer (not the anonymous one used to prevent stage sharing) and copy relevant opinions from its session as local propspecs.

I did try to play with the stage as references export option, but regardless of its value no prim is produced for my proxyshape (and no call to the export chaser seems to be made).

After having selected an unshared proxyshape whose stage's edit target points to its session layer (our basic setup), I ran the two following MEL export commands, and both of their logs mention the fact the export of the proxyshape will be skipped due to the nature of its root layer:

file -force -options "exportStagesAsRefs=0;defaultUSDFormat=usda;mergeTransformAndShape=1;includeEmptyTransforms=1" -typ "USD Export" -pr -es "/tmp/export_stagesAsRefs_off.usda";
// Warning: A reference to simple_xformShape could not be exported because the root layer is anonymous. To include this stage, you will need to save the anonymous root layer to disk and re-export the scene.
// Result: /tmp/export_stagesAsRefs_off.usda.usd

file -force -options "exportStagesAsRefs=1;defaultUSDFormat=usda;mergeTransformAndShape=1;includeEmptyTransforms=1" -typ "USD Export" -pr -es "/tmp/export_stagesAsRefs_on.usda";
// Warning: A reference to simple_xformShape could not be exported because the root layer is anonymous. To include this stage, you will need to save the anonymous root layer to disk and re-export the scene.
// Warning: Cannot export the stage in the proxy shape at path '|simple_xform|simple_xformShape': the root layer is anonymous
// Result: /tmp/export_stagesAsRefs_on.usda.usd

And indeed, both exported layers have no prim:

#usda 1.0
(
    defaultPrim = "simple_xform"
    metersPerUnit = 0.01
    upAxis = "Y"
)

Any help or insight would be very welcome, as we are currently squeezed between the need to upgrade to maya-2026 asap (sticking to any version of maya_usd prior to v.0.30.0 is thus impossible) and this new behavior.

Cheers.

[wallworm]

Thanks for confirming. We will look into addressing this. I don't have a simple workaround today, but you could implement a custom primWriter to handle proxyShape nodes that have an anonymous root layer as a workaround.

[pierre-ed]

Hi Shawn.
Thank you very much for this valuable piece of advice. 👍
I will try it out.
Cheers.