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Plastic Reflector Material

Howdy Folks,

I’m trying to make something look and behave like the plastic covering a taillight of a car. I made something that is mediocre at best, and since the bumps are modeled, it’s a seriously heavy object, for something so minor, at 120K polys.

One thing I noticed in the image below is that the light inside the reflector object doesn’t behave like a real world reflector which bounces the light around. When I played with emission, I couldn’t seem to get the desired effect. So what is the best way to cheat that? I’m assuming that a more efficient way would be to use normal maps, but I have no idea what other settings I should be toying with in the material editor.

Any advice would be appreciated.

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Cheers,

Sterling

First, you should bake the geometry in a normal map to optimize the mesh. Then, you might want to look at refraction. I think the effect isn’t working, because the mesh itself doesn’t “bend” the light, which a normal map would do. By using refraction, you can increase the effect.

Thanks. I’m just getting started with custom normal maps, so it’ll be another learning experience. The above image does employ refraction, but it doesn’t seem to be very effective. When I get it working, I’ll post my solution.

That is a serious understatement :stuck_out_tongue:
I also would use a combination of refraction and emissive.
If you want the bumby effect not just by plain normal map, you could use a material based tesselation and world displacement. But dont overdo it :slight_smile:

I would also add in some fakery to the emissive texture of an already-refracted image. The reason being in real life you are going to get multiple levels of refraction adding to that chaotic look. If you just add a bit of noise to your emissive texture before doing the refraction it will make it look like there is a lot more going on. You might have to try a few random looking textures.

FYI, this kind of material is called a retro reflector. It’s key characteristic is that it reflects almost all of the light that hits it directly back to the source. Think safety vests, cats eyes, etc. Your best bet would be to use a post process shader to apply an emissive effect masked by a broad specular highlight.

That’s good information to know. I haven’t used a post processor shader before, so I’ll look into it. Are you suggesting that it doesn’t even need a light inside?

-S

Personally I see no reason to use post processing for that, but I’m sure you could do something cool with it. You can easily do the same thing on the material itself and you would have more control.

When you are talking about the light inside, then it is not a retro-reflector. Retro-reflectors only reflect they do not have light sources. Even if you had a retro reflector I’d more try to get the effect by using a combination of high specular and roughness variation, but it may be hard to get something that pops enough without some emissive fakery.

I don’t know the actual specific, real-world differences between a retro-reflector and a the plastic over a car’s tail light. I’m actually trying to make a retro backlit button. This is the closest thing I can find as a reference for the what would cover the light behind it.

-Sterling

Thats quickly explained.
A retro reflector reflects all incomming light.
A light cover on a car is scattering the light from the bulb into a certain area…The same as a “fresnel” lense in a lighthouse…
So:
Retro reflector = Reflective. Bounce back in the same direction it came. Parallel rays stay parallel.
Tail light cover = Transmissive. Light shines through. Parallel rays diverge, diffuse scattering.
:smiley:

Thanks for the clarification. The I definitely want the latter as my scene is dimly lit, so not much to reflect.