UE5.0.3 creates an assertion while adding unweighted bones to a metahuman

[AchimTuran]

Member lAKKWHY reported the issue here, https://discord.com/channels/671128082110742561/762949358417084426/996773343514599494

And gave detailed information about the occuring error message here, https://discord.com/channels/671128082110742561/762949358417084426/996958332776616038

Assertion failed: (Index >= 0) & (Index < ArrayNum)
[File:D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 691] Array index out of bounds: -1 from an array of size 359

UnrealEditor_Engine 
i Get this error message from TTToolbox-unweighted-bones plugin

AdvancedLocomotionSystemV.log

[AchimTuran]

I tested the latest state of the unweighted feature branch with 5.0.3

Mixamo character seems still to work fine

Quoted from: https://discord.com/channels/671128082110742561/762949358417084426/997011808697196607

[AchimTuran]

MetaHuman Hudson worked so far as well

Adding sockets and virtual bones with TTToolbox seems to work as well.

[AchimTuran]

Hmmm... I need the exact same MetaHuman and the exact steps that were used to create the issue. I can not reproduce the issue locally on my machine. 😞

Wondering a little bit if the user had already added the virtual bones. 🤔

I do have the following questions for lAKKWHY:

1. Which exact steps were used to reproduce the issue?
2. Which MetaHuman is used that creates the assertion (it prevents a crash but sadly still closes the editor)?
3. Are the virtual bones already added to the skeleton asset of the MetaHuman?

[AchimTuran]

I'm getting this issue when I add the required virtual bones for ALS and then try to add the unweighted bones that I get this assertion as well.

Well... That is super sad!!!

if (!Skeleton->AddNewVirtualBone(SourceBoneName, TargetBoneName, newVirtualBoneName))

https://github.com/tuatec/TTToolbox/blob/master/Source/TTToolbox/Private/TTToolboxBlueprintLibrary.cpp#L153
Has an silent error if the source or target bone do not exist in the skeleton asset the virtual bones will be added to the asset without an error. And later I'm not able to open the skeleton asset again. 🙈

@ lAKKWHY
Please remove the virtual bones and try again.

[4X3E12]

Hello here @ lAKKWHY
i,m using HANA metahuman.
I uploaded a video on discord channel https://cdn.discordapp.com/attachments/762949358417084426/997050379265130537/2022-07-14_13-25-54.mkv
Virtual Bones added but not working showing in Metahuman character. you can see in video.
Editor is not crashing when i recorded this video, because unweighted bones already exists i think!!

here is image of

[AchimTuran]

I added some fixes to this issue in the unweighted bones feature branch, see #2 (comment). In my case it fixed the wrong bone index access. Details can be found here, #2 (comment).

[4X3E12]

OK I'm checking

[AchimTuran]

For me the issue was resolved, which is the reason why I now close this ticket here. If you still have the issue feel free to reopen and we will have a look at it again. 😉

I wish you all the success within your character integration journey. 💪