Anisotropy doesn't work as expected (or used to work on Sketchfab)

Summary

Anisotropy doesn’t perform as expected, and taking an anisotropic texture that worked perfectly fine on Sketchfab now produces incorrect results.

What type of bug are you experiencing?

UI/Tools

Steps to Reproduce

Create any type of anisotropic texture you can think of, including the same kind that used to work on Sketchfab, and apply it to a model.

Expected Result

Expected an anisotropic effect…

Observed Result

It bends the light incorrectly, and in an unexpected manner.

Platform

PC

Operating System

Win10

Screenshots

Top is from Sketchfab, bottom is exact same asset/textures in Fab.


Hello, could you give me a link to your sketchfab and fab models so I can look into it please?

https://www.fab.com/portal/listings/2bb4a022-a948-42ec-9f22-ffb01e830d71/preview?from=listings_list

Not sure if the fab link will work, not sure how to share them yet (if it’s possible at the moment).

Thank you.
That’s ok I don’t need the Fab link. I can repro the issue indeed. I’m on it.
Don’t try to edit the model. It’s going to work eventually.
I’ll keep you updated.

1 Like

Hello, this issue has been fixed.
However there is a catch.
Anisotropy in sketchfab was done in a time where it was not very widely used in the industry and lacked a standard way to describe it.
With Fab, we want to focus on being able to export models to any DCC, and for this we support glTF format.
glTF has an extension for anisotropy that has a specific parametrization and we are now using something compatible in our viewer.
it is described here if you want more information glTF/extensions/2.0/Khronos/KHR_materials_anisotropy/README.md at main · KhronosGroup/glTF · GitHub
In short, we don’t support the “flipXY” flag that was there in sketchfab, and that you used for this model.
When you load your model you will see a warning mentioning this, and you will see that the anisotropy effect is actually rotating with the vinyl.
But, in this model particular case, because the anisotropy texture is centered, it can be fixed with a trick.
You need to go in the anisotropy textures parameters and set the UV scale U value to -1 instead of 1.
here is a video demonstrating the workaround.

Of course, after that you have to save your changes.
I hope it helps

1 Like

Amazing, thank you so much. I really appreciate the help Remy, and great job Fab team! :+1:

1 Like