glTF importer ignores KHR_materials_pbrSpecularGlossiness section

[seadra]

Godot version:
37aab45

OS/device including version:
Debian GNU/Linux

Issue description:
Some glTF files (example) store the texture information in KHR_materials_pbrSpecularGlossiness section. Right now, these are silently ignored but Godot can convert the specular-glossiness workflow numbers into metal-roughness numbers using the conversion mentioned in this document and make it look correct.

Steps to reproduce:
Import a glTF file with KHR_materials_pbrSpecularGlossiness section.

[seadra]

BTW, importing that glTF file with Gen Lightmaps option enabled crashes Godot editor.

[LinuxUserGD]

Can you import the glTF file in Blender?
For instance https://github.com/ksons/gltf-blender-importer

[seadra]

Similar to the other glTF issue I created, this is also about the importer.

Godot importer for assets prepared in metallic-roughness work is OK. Godot doesn't seem to support specular-workflow, but there are such assets online, and Godot silently drops the specular-workflow textures. This is true regardless of the exporter you use.

[capnm]

godot3 uses the new metallic-roughness model, also it works as expected.
IMO the actual bug is, that godot doesn't fail to load the model in the xtensionsRequired case:

[fire]

Godot Engine isn't required to support KHR_materials_pbrSpecularGlossiness.

I agree.

Godot Engine should fail the file with an ERR_FILE_UNRECOGNIZED or FAILED with a message saying that Specular Glossiness is not supported.

https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness

https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#specifying-extensions

[KoBeWi]

Can anyone still reproduce this bug in Godot 3.2.3 or any later release?
The linked models died.

[fire]

As far as I know this is still valid because my pr for it is unmerged.

If it helps I can give an example model.

https://sketchfab.com/3d-models/scifi-girl-v01-96340701c2ed4d37851c7d9109eee9c0#download This one has gloss spec.