Katana crash loading USD with material facesets

[pmolodo]

Description of Issue

If you export to USD a maya mesh that has two different component groups, both assigned to the same material, then when you try to import that USD into katana, katana will crash

Steps to Reproduce

1. Unzip the attached file somewhere
2. Open cube_material_faceSets_crash.ma in maya
3. Export it to usd
4. In katana, create a pxrUsdIn, and point it at the created usd
5. Set your view node to your pxrUsdIn node, then expand the scene hierarchy until you can see the children of the cube node - it should crash

System Information (OS, Hardware)

Linux

Package Versions

usd-0.7.6

cube_material_faceSets_crash.zip

[spiffmon]

Hah. This points out a critical flaw in our face set encoding design. Because it uses a single relationship paired with the "array of sets in the partition", no two sets can share the same target. The question is how fundamental a redesign we need to pursue; we have already encountered some friction with MaterialX in our design. From a Luma perspective, do you think the Alembic-style encoding, with its own round tripping problems we tried to avoid, is a better overall model to pursue?

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--SpiffiPhone

On Jul 5, 2017, at 7:00 PM, Paul Molodowitch ***@***.***> wrote: Description of Issue If you export to USD a maya mesh that has two different component groups, both assigned to the same material, then when you try to import that USD into katana, katana will crash Steps to Reproduce Unzip the attached file somewhere Open cube_material_faceSets_crash.ma in maya Export it to usd In katana, create a pxrUsdIn, and point it at the created usd Set your view node to your pxrUsdIn node, then expand the scene hierarchy until you can see the children of the cube node - it should crash System Information (OS, Hardware) Linux Package Versions usd-0.7.6 cube_material_faceSets_crash.zip — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[chadrik]

We prohibit the use of face assignment (in this instance, an animator slipped one by our relatively new USD export process) so our goal was simply to get the code to a state where it would not crash if that happened again. I personally don't have an opinion on this but maybe @elrond79 does. On Wed, Jul 5, 2017 at 11:52 PM F. Sebastian (spiff) Grassia < notifications@github.com> wrote:

…

Hah. This points out a critical flaw in our face set encoding design. Because it uses a single relationship paired with the "array of sets in the partition", no two sets can share the same target. The question is how fundamental a redesign we need to pursue; we have already encountered some friction with MaterialX in our design. From a Luma perspective, do you think the Alembic-style encoding, with its own round tripping problems we tried to avoid, is a better overall model to pursue? --SpiffiPhone > On Jul 5, 2017, at 7:00 PM, Paul Molodowitch ***@***.***> wrote: > > Description of Issue > > If you export to USD a maya mesh that has two different component groups, both assigned to the same material, then when you try to import that USD into katana, katana will crash > > Steps to Reproduce > > Unzip the attached file somewhere > Open cube_material_faceSets_crash.ma in maya > Export it to usd > In katana, create a pxrUsdIn, and point it at the created usd > Set your view node to your pxrUsdIn node, then expand the scene hierarchy until you can see the children of the cube node - it should crash > System Information (OS, Hardware) > > Linux > > Package Versions > > usd-0.7.6 > > cube_material_faceSets_crash.zip > > — > You are receiving this because you are subscribed to this thread. > Reply to this email directly, view it on GitHub, or mute the thread. > — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#235 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAD3E-NdahbhxiEZdG7Nl4GhzJHkjSYkks5sLFnggaJpZM4OPEnL> .

[pmolodo]

I think this might just be a bug in the maya exporter, rather than a flaw in the design (at least as far as Maya material assignment is concerned). ie, at an attribute level, Maya will happily let you assign two different component groups from the same shape to the same shading group... but I believe functionally it's equivalent to just having all the faces in one group. So just changing the exporter to check for this case, and then combine the face sets, should be good.

[spiffmon]

Thanks, guys! I think we can make both Maya and katana plugins more robust.

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--SpiffiPhone

On Jul 5, 2017, at 9:54 PM, Paul Molodowitch ***@***.***> wrote: I think this might just be a bug in the maya exporter, rather than a flaw in the design (at least as far as Maya material assignment is concerned). ie, at an attribute level, Maya will happily let you assign two different component groups from the same shape to the same shading group... but I believe functionally it's equivalent to just having all the faces in one group. So just changing the exporter to check for this case, and then combine the face sets, should be good. — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[jtran56]

Filed as internal issue #148363.

[sunyab]

Cleaning up old issues, the Katana and Maya plugins have long been retired from the distribution.