(Fixed) [HOU-1485] V-Ray Car Paint - Coat Layer has no GTR Tail falloff value.

V-Ray V-Ray for Houdini General
1

Hi guys.

I am trying to make an Automotive material using Vray car paint.

I would preffer to use the coat parameter to drive the reflective layer but there is no GGX (GTR) Tail falloff parameter.

I preffer not to blend a vray coat overtop using a faloff map as it doesnt look the same.

There is a visible difference between a vray material using its own specular compared to one that gets its specular from a blend material using a falloff curve.

2

Hey, @stevejjd ,

under the hood, the Car Paint material uses Blinn, not GGX for the Coat layer. I’m told a newer version using GGX is being worked on, and the fall-off will be exposed once it is ready.

Anyway, I’ve prepared an example file for you, you can find it here: https://drive.google.com/file/d/1YEal4OW2D917J6iNdKRA7nHP3MZLP9E3/view?usp=sharing
It uses a Layered BRDF with the Car Paint w/o a Coat layer, and a V-Ray Material on top. I got the V-Ray Material’s reflections pretty close to the Car Paints’. You can set the Reflection BRDF to GGX and play with the fall-off. Please ping me if you hit any issues.

Hope that helps!

3

Thank you so much for your help :slight_smile: