Bug report: MToon Outline Exported Missing. Different from Blender Preview

[tdw46]

Describe the bug

When I setup MToon outline in blender, preview looks fine:

When viewing the VRM in other VRM apps the MToon outline is missing from the right side of the character's neck:

To Reproduce

Steps to reproduce the behavior:

1. Open: This File
2. You'll notice outline is missing from character right side of neck
3. Import and re-export from blender, the issue will persist

Expected behavior

Preview in blender should match exports. But also, MToon outline should export correctly.

Desktop (please complete the following information)

• OS: Windows 11
• Blender 4.2, 4.3
• Addon Version: 2.31.0

[tdw46]

I discovered the issue! The split normals were not pointing in the direction I expected!

Making sure normals are outwards pointing on the neck fixed things.

[saturday06]

Thanks for the research.

It seems that VRM Add-on not previewing the correct outlines at the moment.

Blender's glTF exporter exports split normals. Also, MToon outlines should be displayed in the direction of split normals. The current VRM add-on generates outlines using Geometry Nodes, but Geometry Nodes cannot read split normals.