Bug: PBR shader: $detailmask doesn't work with blend mode 10

[lenship2]

Describe the bug

Blend mode 10, which enabled blending bumpmaps, is an incredibly useful detail texture mode. However, it doesn't work with $detailmask, which makes its current implementation very limited.

To Reproduce

1. Have a bumpmapped detail texture and a greyscale detailmask
2. $detailblendmode 10 and $detailmask "[directory]/[texture]_detailmask"
3. Observe in game

Issue Map

detailbug.zip

Expected Behavior

$detailmask should mask the detail texture

Operating System

No response