Falloff node setup similar to 3DS Max falloff node? Need perpendicular / parallel falloff for correct fabric rendering

Question

Notice: After all of the awesome advice given here, I ended up creating a node group that clones 3DS Max's falloff map (for the most part). Feel free to download in my latest answer to this question.

In 3DS Max and VRay, I can create a "Falloff" map. Here is a description from the docs:

The direction used to specify the angular falloff varies, depending on the methods you choose. However, with the default settings, the map generates white on faces whose normals point outward from the current view, and black on faces whose normals are parallel to the current view.

I'm not sure at all how to implement this in Blender - I am not a node wizard. but it's extremely valuable when creating materials for fabrics and textiles. Intuition tells me someone has managed to implement this already.

Here's a screenshot:

Edit: I just created a couple of images that show this map in action when rendering clothing / textiles. I would recommend opening both images in to tabs and then quickly cycling between them to see the change.

With Falloff:

Without Falloff:

Going to add an edit here. Here are the things I have tried so-far without much luck:

1. Layer Weight Node (Facing into MixRGB factor)
2. Fresnel Node
3. Velvet Shader BSDF (This has given me the best results so-far)

Velvet Shader attempt:

Can someone point me to a working/better implementation or substitute for this behavior?

Really appreciate any help at all.

Answer 1

"With the default settings, the map generates white on faces whose normals point outward from the current view, and black on faces whose normals are parallel to the current view."

What you're describing sounds like the dot product of the incoming vector and the normal vector. Probably, clamped:

If I've misunderstood what "point outward" means, you may want to multiply the dot product by -1.0 instead of 1.0.

Use of the incoming vector might not be appropriate for Cycles-- some variation of the view vector (from camera data) might be appropriate instead, although I can't figure out what space that vector is in; or, you might just do it for camera rays only. Remember, incoming vector can be incoming from camera, or incoming from reflection or refraction or anything else, given Cycles bounces.

The dot product does not give a value that varies linearly with angle. It varies linearly with projection of incoming onto normal, which isn't the same thing. It is common to prefer arccosine(dot(v1,v2)) to dot(v1,v2), which varies linearly with the angle instead.

Which requires a bit of remapping to pi-based stuff. Both of these examples are black where the normal is perpendicular to incoming and white where it is parallel with incoming; the difference is how they interpolate between those two colors.

Answer 2

This effect is built into the Principled BSDF node and can be controlled via the Sheen parameter.

Here is a cloth object without sheen, with sheen set to 2, and with sheen tint set to 1 respectively.

Answer 3

So I took it upon myself today to create a flexible clone of 3DS Max's falloff map after reading all of the helpful replies to this thread. I came up with a pretty good node group that I'm quite happy with.

It's very simple, but there is a lot of flexibility with regards to how you can control the intensity and "look" of the falloff. You can dial in extremes as well as very subtle effects.

Like in 3DS Max, you can mix textures/maps by populating the side and front color inputs.

Hope this helps someone.

Download: