I’m trying to create material of scratched transparent plastic, but thing is - making scratches with bump or normal map looks like scratches in jello, which is not what i want. Such scratches are… umm, shimmering? They reflect in special way on light, I managed to achieve something like that with emission, but it’s still not what i need. Anyone?
How does scratches in jello look like ? not sure what jello is. Image search returns something between marmelade and candy. It could be down to the IOR you’re using : every transmissive material is different in that regard.
cf https://www.cgdirector.com/ior-index-of-refraction-list/
It could also be that the texture size you’re using may not be enough to display very tiny scratches. Instead of using a single “atlas” texture containing many scratches, use several other maps that each contain just one or a few scratches. Then, use the Voronoi texture-bombing trick to scatter them around the UV space of your object.
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What is the voronoi texture bombing trick? I saw it mentioned before, and can imagine what it is but I’d like to go through an actual tutorial
No, issue is not about size, I’m about micro scratches, the way they shine, something like this, but using texture only, with minimal amount of nodes, so it was easier to export to engine. Also those scratches sometimes look like they’re inside (I need to get to pc to show what do i mean)
Not sure, but it reminded me about technic that helps break repeating pattern of tiles
The effect you’re after is highly anisotropic… If your engine doesn’t have that kind of shading you’ll be out of luck.
But if it does, then you’ll need a texture for the anisotropic value, and a Texture for the Tangent vector (or for the rotation).
You can create such textures inside blender with ease, but they need to have a good resolution.
There was something…wait… this site also has search function 
…a thread started in 2014… last post Aprill 2022:
Can you show examples of what you are after and examples of what you have achieved.
I guess one of the problems is that scratches are often small (microscopic) and would represent sub pixel detail - something cycles doesn’t handle well. You can get part way there as the post above demonstrates, but there may be limitations.
Rendering glints and scratches are an active area of research (see paper below). Sadly Cycles does not (to my knowledge) include anything like this currently.