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Highlight corners without UVs

Hi everyone!

I’m coming to all of you with a desperate cry of help. I’m currently trying to recreate the taillights of a car, and I’m trying to make it as realistic as possible.
The problem is that this is really pushing my skill-boundaries to the max, since I’m still fairly new.

So heres the problem:
I’m trying to recreate the look of these glowing LED taillights. I especially like the little darker areas that run along the corners of the geometry.
101c0e2389b9ac6042ae5820e5f93c6525f18786.jpeg

The problem I have is that I have no idea how to make them. I guess with proper UV unwrapping and some time you could make a texture to mask them out, but let’s pretent this happens in a work environment where there’s no time for that and it has to work without it.

Is there a way to sample the object normals against each other to get the edges highligted in a way that it could be used as a mask to dim down on the emmisive?

Basically it’s a material that let’s edges glow like this without the use of textures:
f5f7e72c1677540ae8c7671ac75dfabff03a9eb0.jpeg

I’d apprechiate any input I could get on this. :slight_smile:

Hello!

Do it only in your normal map with nDo or Substance Painter by example, you just would have to draw these shapes where you want. If you don’t know these apps, search in YouTube, you have plenty of demonstrations :wink:

But this requires UVs and texture work. I’d love to be able to do some vector math magic in the material to get sample the object normals in a way that it gives me this effect.

Like I said, imagine there’s no time in your workflow for UV work and texturing on this part and it has to happen in the shader itself :slight_smile:

That effect is due to the refraction of light through the car light material. I don’t think the engine is really capable of rendering refraction like that, what is probably best is to have a clear glass outer material and then a flat material underneath with a texture of the light using an emissive texture.

Ohh, have no idea why I thought he was talking about the chassis mesh. This kind of lights are possible to do. You might want to check the real lights but most likely what is going on here is the brighter parts are pockets of air, the less transparent parts are simply painted darker from inside, or have a thicker piece of plastic on outer side. You can model a plastic part itself and render with translucency, masking out non transparent parts. Under the plastic place a material with very bright emmissive. For darker edges you could use UVs or vertex color, make something like a bevel with multiple levels and then paint vertices of the edge darker.

Okay so after analysing the picture together with the geometry I have (we’ve got the original CAD-geometry) and it seems like there actually is a transparent object in front of another one that’s diffusing the light of the LEDs behind it. And the transparent object might also be what’s refracting the light so it’s causing darker areas. The thing is, that it’s only 1 object there, so it either has a coating on the inside that’s causing the diffusing, or the whole object istself works in a different way. :slight_smile:

Either way, I get that it’s not possible to render it in a physically correct way, I just want to fake it so it’s as close to the original as possible, and so far I’m still not shure how to do that. Guess I’ll have to put some work in, make a retopo of the part (original CAD data always has horrible tesselation since it’s automatically tesselated from NURBS) and actually try to work with vertex colors and textures.

I’ll see what I can to, and ask if I’m allowed to share screenshots. :slight_smile:

EDIT:
Okay the data itself is still secret, so no way of showing what I’m doing here. :frowning:

“Basically it’s a material that let’s edges glow like this without the use of textures” Isn’t this one for post-processing?