Keeping extras from VRM

[fire]

Hello,

I have a vrm file. It's a modification of a glb file.

When I rename it to a glb, and then do .\gltfpack.exe -ke -kn -km -ke -i '.\Short Haired Girl Black Dress Less Poly 3.glb' -o 'Short Haired Girl Black Dress Less Poly 4.glb'.

VRM importers fails to load it as a vrm.

I have tried the -ke option.

Any suggestions?

Short Haired Girl Black Dress Less Poly 3.zip

All Rights Reserved. Ask me if you want license details.

https://github.com/saturday06/VRM_IMPORTER_for_Blender is an blender addon for VRM.

[avaer]

It would be useful to us too if the VRM extensions were not removed during the meshopt process. 👍

[fire]

This is my attempt to patch meshoptimizer.

fire#1

Looking for suggestions.

git clone https://github.com/fire/meshoptimizer.git -b vrm 
cd meshoptimizer
mkdir build
cd build
cmake -DMESHOPT_BUILD_GLTFPACK=ON ..
make
wget https://github.com/Miraikomachi/MiraikomachiVRM/raw/master/Miraikomachi.vrm
./gltfpack -si 0.1 -noq -ke -ke -i "Miraikomachi.vrm" -o "Miraikomachi Optimize.vrm"
# Open in a vrm importer.

My Blender vrm importer is currently failing so it's hard to verify even on the standard alicia model.

[zeux]

I'm not familiar with VRM but if it's just about preserving the top-level extension node "VRM", it should be simple. The change above might be too broad though, as it would preserve some top-level extensions where extra work needs to be performed to make the content work, e.g. KHR_xmp.

My suggestion thus would be to simply detect when "VRM" is present in the extension list (regardless of input options, or maybe using -ke for this is fine) and, if so, output just that extension blob, using appendJson which performs JSON minification.

Feel free to submit a PR along these lines. I don't have a way to test this so testing suggestions would be welcome.

[fire]

BEFORE 7.6M AliciaSolid_vrm-0.51.vrm
AFTER 5.5M   AliciaSolid_vrm-0.51-opt.vrm

From https://github.com/vrm-c/UniVRM/tree/master/Tests/Models/Alicia_vrm-0.51

Using https://vrm-viewer.yukimochi.io/ importer.

AliciaSolid_vrm_opt.zip from

Notes for posterity.

On fire@7ab13de

./gltfpack -si 0.8 -noq -km -kn -ke -i "AliciaSolid_vrm-0.51.vrm" -o  "AliciaSolid_vrm-0.51-opt.vrm"

[fire]

Thanks for the review.

I can scan for the "VRM" extension. However, I noticed some problems with extras not being sent through.

1. Enable "VRM" when seen
2. Keep extras code the same.

[fire]

I slept thinking about this optimization, because Godot Engine added autolod, I don't have a requirement for this.

The pr is salvageable for all those webxr based avatar multiverses out there. @avaer

[Ry3yr]

I hope vrm support is still being worked on.

The only other "tool" https://github.com/infosia/vrmpack?tab=readme-ov-file that was apparantly "merged into meshoptimizer" is really a drag to compile and use...

And messing with blendshapes and such is hardly a good way to downsize a .vrm.

After all there are not many good tools for vrm (pmx has dozen.. but vrm ? )

PS:

And yes, vrm is heavily glb based (unity) but vrm has some weird quirks that need to be heeded for it to still be usable.