Add .glTF format as an export option

[RobotRoss]

Feature/enhancement description:
Add the ability to export completed texture to glTF 2.0 compliant .glTF file

.glTF is a next-generation interchange format spearheaded by Khronos
site

Godot also has support for exporting scenes to .glTF
site

Adding the .glTF format would enable Material Maker to be used in applications that are outside the scope of the existing export options.

For now, I'd like the ability to export just the completed textures to glTF, but in future it'd be useful to also export any models which are present in the scene to the same glTF file.

[Calinou]

glTF export isn't available in exported projects in Godot 3.x – it's editor-only. This will have to wait for Godot 4.0 (and for Material Maker to be upgraded to use Godot 4.0).

[clairem-sl]

Now that Godot 4 is out, will this be developed?

[Calinou]

Now that Godot 4 is out, will this be developed?

Material Maker is being ported to Godot 4, but the goal is to get existing features working first.

That said, is glTF supposed to be used as a standard for sharing materials? Shouldn't we use MaterialX for that instead (which Godot 4 can't write directly, so it'd have to be done in script)?

[RobotRoss]

is glTF supposed to be used as a standard for sharing materials?

There's no reason why it couldn't be - Some platforms accept .glTF for materials, but not MaterialX - hence why libraries such as https://github.com/kwokcb/glTF_MaterialX exist.

That said, having MaterialX as an export option isn't a bad idea, but it doesn't replace glTF as an export target.