NodeMaterial: Roughness appears to be broken

[WestLangley]

git bisect suggests #17368, but there are so many commits for which the shader does not even compile, it is hard to pinpoint exactly when the error was introduced.

https://threejs.org/examples/webgl_materials_envmaps_hdr_nodes.html (set metalness to 1)

Three.js version

• [ x ] Dev
• [ x ] r108

[sunag]

I fixed this in NodeMaterial r8, if I am not mistake is related with maxMipLevel, but r8 still need more work to finish...
I will create a PR to fix some issues recently.