Feature: PBR detail texture roughness detail

[November-N]

Which component should be improved?

Rendering

Describe your feature suggestion in more detail

The PBR shader should have an additional blending mode (or possibly more) that uses the detail texture to modulate or add on-top of the roughness map. There should be a mode to use the 'overlay' blending mode (values over 128 lighten, values under darken). This would be less useful, but a different mode that blends the detail roughness additively onto it would also be useful I'd think (although less necessary).