differences between collada and glb imports

[canny]

We are comparing rigged mesh export from Blender to Second Life via both .dae and .glb.

We can export both formats so that they behave identically in SL, but only when deformation is limited to the standard m* bones.

As soon as SL volume bones are also marked deform, the .glb result differs slightly from the .dae result after the mesh is worn on the avatar. The imported static meshes are identical. The difference appears only after wearing, when the SL rig actually deforms the mesh.

A few details:

-same source rig and mesh

• same visible export mesh in Blender before writing the file

• same result in SL when volume bones are not deforming

• mismatch appears only when volume bones participate

• note that volume bones have the known non-neutral/rest-scale oddities

Does anyone know how SL’s .glb importer handles volume bones internally, especially their rest/bind transforms or scaling? We are trying to determine whether the difference comes from Blender glTF export, Avastar/Collada export assumptions, or SL’s handling of volume-bone skinning.

https://secondlife.canny.io/admin/feedback/bug-reports/p/differences-between-collada-and-glb-imports

Test plan:

• Get the test content from https://github.com/secondlife/viewer-private/issues/581
• Rest of test TBD

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[canny]

This issue has been linked to a Canny post: differences between collada and glb imports 🎉