Recommend Blender export options

[doganulus]

I am not very familiar with computer graphics concepts. So I want to ask your opinion and suggestions regarding Blender export options to FBX and GLTF.

Currently, Blender Python API supports FBX and GLTF export using the following methods:

• FBX: https://docs.blender.org/api/current/bpy.ops.export_scene.html#bpy.ops.export_scene.fbx
• GLTF: https://docs.blender.org/api/current/bpy.ops.export_scene.html#bpy.ops.export_scene.gltf

For example, I realized the option export_hierarchy_full_collections=True must be set for GLTF exports to keep the XOM hierarchy; otherwise, it exports a flat set of objects, which is not compliant with the OpenMaterial standard.

Would you happen to have other recommendations for export options?

[ClemensLinnhoff]

What I typically do is select the hierarchy of the Grp_Root:

Then go to File -> Export -> glTF 2.0.
Under Include -> Limit to I select Selected Objects. I leave all other settings to default.

That will export an ASAM OpenMATERIAL 3D compliant gltf file. Make sure the +Y Up option under Transform is selected. It should be selected by default.

For FBX the workflow should be similar.

[doganulus]

I see you organize your hierarchy using empty axes. I had first used collections instead.

Then I realized you added an annotation (T) next to node names in the OpenMaterial-3D standard. So I converted them into an empty axes node if the name contains a (T), showing that this node has a translation.

Then, if you use collections for the rest, then we need to set export_hierarchy_full_collections=True when exporting.

Also, I found it useful to disable vertex colors as I could not manage to export their material rendered properly when vertex colors are exported.

[ClemensLinnhoff]

Ah yes, we create the entire hierarchy with empty nodes. In the standard we cannot reference explicit tools, but it is generally described here.

Group nodes are empty nodes representing the coordinate origin of the contained geometry.

I am no expert, but generally, vertex colors should work.

[ClemensLinnhoff]

Maybe we could still add a blender file to the examples and add a readme with export instructions.

[doganulus]

I started a Blender extension under https://github.com/bounverif/openx-assets. The addon has some helper functions to export assets, move the asset to the origin as the OpenMaterial states, and create an empty vehicle hierarchy for you.

Not released yet and working on the data model in Blender. This brings more ideas.

[ClemensLinnhoff]

Sounds great. I will have a look and then we can link the extension in a Readme here.