Switch parented to DOF receives unpredictable rotations

[avan069]

Per title, in v1.0.17, after parenting a switch to a rotation DOF (probably same result for all types,) that switch and its children do not correctly animate after export. Prior to export, in Blender, the parented component moves exactly as expected. I suspect some sort of transformation issue.

Many attempts made in the example from the pictures to ensure no unapplied scale issues or similar might be interfering. Complete rebuilds (from scratch) of DOF chain were attempted multiple times. Resultant displacement in the BML export was usually identical, in one occasion I saw the same displacement but rotated 90 degrees about the axis of rotation.

In the example images, the incorrectly displaced components would rotate with the DOF, maintaining the indicated displacement in the DOF's frame of reference.

[MC-Deedle]

Ok I’ve got a handle on the cause here but writing a neat solution that doesn’t cause a regression is likely a bit of work

[avan069]

Is it confined to switches/DOFs or is it a more fundamental problem with transformations in the export? If so, and there is some Blender-esque way to apply transforms prior to export (if you know what I mean) that might kill two birds with one stone

[MC-Deedle]

Not sure yet. I need to test whether only meshes are affected, or bbls and other node types as well. It’s just wonky code I think. We parse nodes recursively, but in doing this the nested “transformations” should also be “additive” between layers but they’re kind of handled external to this process.

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On Sat, 7 Jun 2025 at 8:08 am, avan069 ***@***.***> wrote: *avan069* left a comment (BenchmarkSims/bms-blender-plugin#48) <#48 (comment)> Is it confined to switches/DOFs or is it a more fundamental problem with transformations in the export? If so, and there is some Blender-esque way to apply transforms prior to export (if you know what I mean) that might kill two birds with one stone — Reply to this email directly, view it on GitHub <#48 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BLAT453EAG2MRFME2WXAKFD3CIGPVAVCNFSM6AAAAAB6UJWJECVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDSNJQHEZDKMRSGI> . You are receiving this because you were assigned.Message ID: ***@***.***>

[avan069]

Not sure yet. I need to test whether only meshes are affected, or bbls and
other node types as well.

It’s just wonky code I think. We parse nodes recursively, but in doing this
the nested “transformations” should also be “additive” between layers but
they’re kind of handled external to this process.
…

I suppose that's why the Blender group discourages recursion in general.

[MC-Deedle]

Not my view. Just needs to be applied consistently.

[hamdankhan1208]

you can try switch->dof->mesh (kaos recommendation:might work according)

[avan069]

you can try switch->dof->mesh (kaos recommendation:might work according)

I'm embarrassed that I had not tried that - it does work. However, this is still a legitimate bug