I'm working on a brushed aluminum material on a flat surface. but without the anisotropic it doesn't look right. I want the light to bend but not the way it does by just adding anisotropic in the principal shader. That would give me a radial brushed effect like on a CD I want the reflections to be stretched like in this photo example as if the aluminum was brushed in one direction. Thankful for help.enter image description here


1 Answer 1


Regardless of whether you use Principled BSDF or Anisotropic BSDF, the direction of anisotropy is set by the combination of the Tangent input and the Rotation field. The tangent is a world-space vector perpendicular to the normal, set most easily by a tangent node; the rotation rotates the given vector around the normal.

If you use a tangent node to input a radial tangent, you'll get a radial tangent, in the object-space plane specified. If you use a tangent node to input a UV tangent, you'll get the vector of increasing U for the UV map you specify.

You can even create an arbitrary, per-sample vector yourself, without using the tangent node. (Notably, you can make a radial by hand that's better than the built-in radial. But mostly nobody's going to take advantage of home-built tangents.)

enter image description here

If you don't specify a tangent, anisotropy defaults to a radial Z tangent.

  • $\begingroup$ Oh, nice. That pesky tangent input $\endgroup$ Jun 14, 2021 at 16:46
  • $\begingroup$ is the tangent node possible to use with the Principaled node? $\endgroup$
    – Rock
    Jun 14, 2021 at 17:17
  • $\begingroup$ @Rock Yes, it's exactly the same for a principled BSDF, except "rotation" is called "anisotropic rotation." $\endgroup$
    – Nathan
    Jun 14, 2021 at 17:24

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