Alpha cutoff materials are alpha blending?

[Cameron-Micka]

Describe the bug
I have a file named WinterCabin.glb that renders like this in Unity:

And like this in other glTF viewers:

I took a stab at debugging the issue and it looks like the two materials within WinterCabin.glb are marked as "alphaMode":"MASK" (which is kind of silly since I don't really need to be). Anyway, when I import the file with glTFast the two material's "Surface Types" are "Transparent" (rather than "Opaque") which is enabling alpha blending and the sorting artifacts you see in the first image.

Files
WinterCabin.zip

To Reproduce
Steps to reproduce the behavior:

1. Import WinterCabin.glb into your Unity project*
2. Drag and drop the imported model into a Unity scene
3. See artifacts

* Note the project this was tested in is using Unity 2022.3, URP, and glTFast 6.10.1.

Expected behavior
The WinterCabin.glb renders without sorting artifacts.

I think the issue in this case is the GetSpecularShaderFeatures method enables alpha blending if the mode is anything but opaque. Maybe the check in that method should be if (gltfMaterial.GetAlphaMode() == AlphaMode.Blend) so that AlphaMode.Mask materials can also be opaque?

Desktop (please complete the following information):

• glTFast version 6.10.1
• Unity Editor version 2022.3.34f1
• Render Pipeline and version Universal Render Pipeline 14.0.11 (Forward rendering)
• Platform: Editor (Windows)