Multiple mesh Blendshape data import fails to rebuild combination target

[MadScrat]

Hello Autodesk,

 This is probably the first time I ever use the forum to ask for a fix. 🙂 So, as the title says, if you have a group blendshape(One with multiple orig meshes), and if you import the blendshape data you previously exported containing combination shapes done by Shape Editor UI, these combination shapes doesn't get re-connected as it was before export. 

// Error: file: C:/Program Files/Autodesk/Maya2023/scripts/others/blendShapeImportShapes.mel line 22: Connection not made: 'combinationShape1.outputWeight' -> 'blendShape1.pSphere10'. Destination attribute must be writable.
// Error: file: C:/Program Files/Autodesk/Maya2023/scripts/others/blendShapeImportShapes.mel line 22: Problems occurred with dependency graph setup.

In my scene I have this:

The shape editor before I export shows:

The shape editor after I import, you can see the pSphere10 target doesn't get connected, but the deltas I can confirm are in there.

If you have a NON-MULTIPLE blendshape, the import works just fine, and all combos gets reconnected again.

Thank you,

-Daniel

[Kahylan]

Hi!

In Maya 2022, exporting a setup like this to ASCII and reimporting seems to work fine, maybe this bug is 2023 related.

Can you manually reconnect the connection from 'combinationShape1.outputWeight' to 'blendShape1.pSphere10' and/or reconnect them using this script:

connectAttr "combinationShape1.outputWeight" "blendShape1.pSphere10"

Or does this result in the same error?

[MadScrat]

Hey Kahylan, thanks for jumping in! Ok, I think I didn't explain well, but it's not during the opening of the file that it fails, it fails during the import of the blendshape data using the Shape Editor UI. It has nothing to do with Maya ASCCI file type.  It's actually a .shp file type. 

After you import the .shp file, the combination node is not even created after the import fails to complete. So there is nothing to connect in the first place.   This is not a problem in 2023 only, it also happens in 2022. Thanks for mentioning it, I should have also explained that I tried before in different versions.

Thanks again,

-Daniel

[Kahylan]

Oh sry, I wasn't familiar with this workflow, you never stop learning^^

It looks like this just doesn't work currently, maybe it's because there are cycles in multi mesh blendshapes. Maya cycle-checked me multiple times while testing out the setup. Which could lead to the problem at hand, as it seems like Maya is trying to connect the combinationShape before creating the node and therefore erroring out. So I think you'll need to recreate the connections after the import.

if you only have a few combination shapes, you could just reconnect them using the method of selecting drivers first and target last and then using the "shapes -> set as Combination Target" command in the shape editor. Which will create the comboShape and connect them correclty again.

If you have a lot of combination Targets on multi-shapes, you should probably write a script that checks the connections on combinationShapes and writes them out to a separate file on your disk, so you can import the file and create everything that is needed with a custom reconnection script.

[MadScrat]

Thanks again, Kahylan!  I know that we can do scripts to solve this easily in the end, but it's just not cool to have this erroring out in a more complex system and do a custom patch on top of it to fix something that it's clearly broken. 😞 I was just hoping that Autodesk would first see this and then fix this problem, otherwise, I would have to write a whole module to deal with blend shape data, which won't be my first time, but it will be another pain on top of all other things I have to do!  😞  Thanks again!

[mcginnc]

Hi - I've done what I think are your exact steps, but can't seem to reproduce this. How did you export this? I see the problem with what you've shown, but need to reproduce here to get it fixed. 

Thanks,

Catherine

[Kahylan]

Hi @mcginnc

I managed to reproduce the problem by doing the following:

1) create 3 spheres

2) group them

3) while having the group selected hit "create a Blenshape" in the shapes editor

4) create two targets for the blendshape

5) add a combination target for the existing targets

6) select the blendshape and use the "File -> Export Shapes" command in the shapes editor

7) delete the targets

😎 select the Blenshape and use the "File -> Import Shapes" command in the shapes editor

The command should crash after the targets are created and before the combinationShape Node is created.

[MadScrat]

You jumped in faster than I could, Kahylan! Thank you!!  😄  Catherine, thanks for jumping in also! I confirm these are the steps! 👍