Principled BSDF - Roughness = 0 - BAD!

2.93.2 - Eevee.

Make a cube.
Make a Principled BSDF for the cube.(Mine is green)
(The default Roughness will be 0.5)

Set Roughness to 0.000. The cube is now black.


Set Roughness to 0.001. The cube is still black.


Set Roughness to 0.010. And BOOM ! The color shows up.
Why is that?

I’m unable to recreate this in either 2.93.5 or 3.0,
It’s either a bug or a driver issue. My guess would be driver issue given how ubiquitous it would be as a bug.

Not sure if it is a bug or a driver issue, are you using an integrated graphic card?
This reminds me of this bug/issue and this thread:

(I have no idea why the thread has a no entry sign) but I can still read it. :thinking:


I am CPU only - Intel(R) HD Graphics 4600. Windows 10. I am but a simple hobbyist.

Now that I know how to fix it, it’s no big deal. Just curious if others have this issue.

Happy Blending !

Was a bug now solved


calpgrmr’s problem reminded me of it.


Thanks so much. Was avoiding new versions of Blender, but may give it a try!

They just dropped 2.93.6, hopefully the fix is included.

Again Thanks!

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For future reference, yes you are. ‘Integrated graphic card’ means you don’t have a separate physical graphics card but instead it’s integrated with the CPU.

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Oops. Guess I had that backwards in my head. Thanks. (duh) :pensive: