Porting glTF reference renderer code to Vulkan

I’ve had great results integrating the sample viewer code here into my own engine:

However, I am having trouble with the sheen fabric material in the Toycar sample. This is what it should look like:

My renderer is showing a weird specular highlight on edges:

Here is just the default metal/roughness reflection without the sheen factor. (The highlights you are seeing move around with the camera position and look sort of like satin material):

And these are the lookup tables I am using:

The cubemaps are generated with this tool:

Has anyone seen this effect before? Any idea why this would be happening? I’ve barely touched the default shader code. My metal/roughness values all match the debug views of the reference renderer.

It appears this may be the cause:

Here is what it looks like in motion:

I actually found this was caused because I forgot to clamp my lookup textures.