Hi,
The scratch generator, as you probably know, isn't a material in itself. You'd have to blend it into a material to get any results. You can do that either in Maya, or straight in Substance Designer.
Let's assume you're making the material in Maya and just want to use the scratches generator.In Substance Designer, I would recommend you make three different outputs: Color, Mask, and Normal. Like this:
You'll use those to make different effects in Maya.
If you're making a Car Paint material like Wes, here's what I would do:
1. Connect the Normal output to Geometry / Bump Mapping (Arnold Standard Surface)
(Remember also to set the bump2D to Tangent Space Normals and to uncheck the flip Red and Green channels)
2. Connect the Color output to Base / Metalness, to make it more metallic where the scratches are. (You might want to put it through a levels equivalent in Maya first, to bring up the blacks. You don't want any plastic after all.)
3. Somehow blend the Color output with your background color (you can use the Mask output to mask where you want it,) and connect it to Base / Color. This'll give you some white in the scratched areas.
4. You might want to play with the roughness of the scratches as well. I'd assume the scratched area is
less glossy so would connect the Mask output alone to the Specular / Roughness.
Again, this is just one way to do it. The scratches can affect different channels of a material in different ways, and it's up to you to determine what works best for the effect you want. I would recommend you make your entire material in Substance Designer, and connect each standard output to the corresponding AIStandard Surface input. You'll se what goes where in the documentation page.
Hope that answers your question!
