Exporting to GLTF in new version causing an error on importing from Blender

Bugs
, ,
1

After updating Babylon.js from 8.12.1 to 8.44.0, I’m experiencing a problem importing GLTF files exported by Babylon.js into Blender:

WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/__init__.py", line 2013, in execute
WARN   | return self.import_gltf2(context)
WARN   | ~~~~~~~~~~~~~~~~~^^^^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/__init__.py", line 2045, in import_gltf2
WARN   | return self.unit_import(self.filepath, import_settings)
WARN   | ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/__init__.py", line 2060, in unit_import
WARN   | BlenderGlTF.create(gltf_importer)
WARN   | ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/blender_gltf.py", line 40, in create
WARN   | BlenderGlTF._create(gltf)
WARN   | ~~~~~~~~~~~~~~~~~~~^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/blender_gltf.py", line 47, in _create
WARN   | BlenderScene.create(gltf)
WARN   | ~~~~~~~~~~~~~~~~~~~^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/scene.py", line 39, in create
WARN   | BlenderNode.create_vnode(gltf, 'root')
WARN   | ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/node.py", line 47, in create_vnode
WARN   | BlenderNode.create_vnode(gltf, child)
WARN   | ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/node.py", line 33, in create_vnode
WARN   | obj = BlenderNode.create_object(gltf, vnode_id)
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/node.py", line 54, in create_object
WARN   | obj = BlenderNode.create_mesh_object(gltf, vnode)
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/node.py", line 304, in create_mesh_object
WARN   | mesh = BlenderMesh.create(gltf, pynode.mesh, pynode.skin)
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/mesh.py", line 26, in create
WARN   | return create_mesh(gltf, mesh_idx, skin_idx)
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/mesh.py", line 47, in create_mesh
WARN   | do_primitives(gltf, mesh_idx, skin_idx, mesh, tmp_ob)
WARN   | ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/blender/imp/mesh.py", line 177, in do_primitives
WARN   | indices = BinaryData.decode_accessor(gltf, prim.indices)
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/io/imp/gltf2_io_binary.py", line 72, in decode_accessor
WARN   | array = BinaryData.decode_accessor_obj(gltf, accessor)
WARN   | File "/usr/share/blender/5.0/scripts/addons_core/io_scene_gltf2/io/imp/gltf2_io_binary.py", line 130, in decode_accessor_obj
WARN   | array = np.frombuffer(
WARN   | buffer_data,
WARN   | dtype=np.dtype(dtype).newbyteorder('<'),
WARN   | count=accessor.count * component_nb,
WARN   | )
WARN   | ValueError: buffer is smaller than requested size

I haven’t had time to delve into the issue yet, but I’m pretty sure the update caused the problem.

I attached a GLTF file that can reproduce the problem (on the Blender’s side). I’ll update the thread if I find anything new.

Thanks!

import problem.zip (4.7 MB)

2

Would you happen to have the source scene you used to generate the file ?

cc @alexchuber to have a look

it looks like the bin name is wrong for some reasons. Also what did you use to export ? (javascript, max, maya.,) ?

4

It’s a bit complicated. I use GLTF2Export.GLTFAsync to export a Babylon scene to GLTF first, then reconstruct it after modifying things like texture paths before sending it to a rendering server (which runs a Blender headless instance).

From what I can see, the final .gltf file references the .bin file with its correct name and size, so I don’t know about a potential mismatch in that part:
```json

“buffers” : [ {
“uri” : “design.bin”,
“byteLength” : 20320
} ],
```

As for the test case, I can create a minimal test case in my app and export it as a .babylon file. However, the Babylon sandbox failed to load it, complaining about missing materials. I’ll attach the exported file, just in case:

scene.babylon.zip (14.6 KB)

5

Yes, could you send a playground of the original scene? I see the binary has a ton of glTF validation errors, but it’s hard to tell where they’re coming from. TY!

EDIT: My bad, I missed the latest response. Can you try exporting the .babylon file with Texture.ForceSerializeBuffers = true so it can be loaded in the Sandbox?

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6

I added this on top of the component that initialises the engine, but the exported file still shows the same errors when I try to import it into the Sandbox:

import * as B from "@babylonjs/core"
...
B.Texture.ForceSerializeBuffers = true

image
image1320×186 17 KB

Am I missing something?

7

Huh, odd. The original issue with the load was that it tried to fetch from an invalid path,

image
image1002×172 31.6 KB

which happens because the .babylon loader uses the serialized texture’s name for the source URL (legacy behavior, I think.) It’s surprising that Texture.ForceSerializeBuffers didn’t work around that. Could you share the new file? Also, any chance you renamed some textures before exporting the scene to .babylon?

Sorry, I know this isn’t the issue you came for! :laughing:

8

Ah, nevermind. It wasn’t the invalid URLs preventing the load, but this:

Can investigate the export issue now.

(Though I am still curious about how the invalid URLs came to be… don’t want to miss a bug!)

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9

This should fix the glTF export:

4 Likes
10

I just tested it with 8.45.5 and can confirm the PR fixed that issue.

Thanks much for the support, as always! :slightly_smiling_face:

3 Likes