How to make proper carbon fiber material?

bugworld

I tried to make some carbon fiber parts but I found I either have to make a offset layer of polygon just to get that plastic "shell" thingy going on, or maybe try to get to know custom shaders, which was not a viable thing to do for me atm.

I paid some attention to racing games, they seemed to make them look very good. I tried the duplicating poly layer approach and the result seemed proper to me, the fiber pattern in normal map plus the transparent poly shell does bring the two layer of specularity effect which I think was important, but was that the right way to do carbon fibers in game? or I shouldn't worry about it and its all shaders?

Visceral

Is this for the UDK? I would take a stock image like this and plug this into the diffuse and specular. I mean it dosnt have to be as advanced as you are making it.

Visceral

You might acctually wanna skip the diffuse on this one and go with a solid color texture and just plug this into your specular.

bugworld

Oh, actually by carbon fiber I meant stuff like this:
http://en.wikipedia.org/wiki/Carbon_fiber-reinforced_polymer
not just the carbon fiber woven fabrics. So usually there's a layer of clear fiber glass of top of the fabric, which at the right lighting could have it's own specular and reflection, so its usually very glossy/reflective and weavingly-textured at the same time. As seen here http://www.carbonfibergear.com/wp-content/uploads/2008/08/weds-sport-carbon-fiber-wheel.jpg or any sports car's shell.

I have no problem emulating the woven carbon fabric by layering that in the normal map(as I found sometimes it's inadequate with spec maps only), it's just I'm not sure how I could mimicking the fiber glass shell. The only option for me is to duplicate a layer of poly and assign a glass material to it. For renders it works pretty well but I'm not sure this method is worthy for games, as it takes quite an extra amount of poly and texture space, if the material was used heavily.

Xoliul

I just tried it with my shader, all it involves is using a different map for for the reflection than you do for the spec. If you really want two separate spec highlights, you'll need a custom shader which calculates both. I figure many games do this if it has to look really good.

bugworld

Different reflection and spec map sounds smart, can I do it without custom shaders? I don't know how to do that especially when there's a fiber texture in the normal map, so whatever map I use for spec or reflection it all contributes to the fiber look.

Games definitely use normal map for the fiber part too, but I'm having trouble finding a proper screenshot showing they do the fiberglass shell as well. So maybe I was just been too anal about it? But couldn't it be very cool if you can put it in your awesome shader Xoliul? I mean that's gotta look sexy on cars... But never mind if it's not worthy resource-wise.

JordanW

The best shader IMO would be one that has an anisotropic specular highlight that uses a crosshatch map to give the 2 different directions of the fibers, You could probably get away with a normal dark diffuse component. Then on top of that i'd have a regular phong highlight with reflection that uses the object normal, that should give the appearance of the clearcoat on top.

Xoliul

Bugworld; not sure what you are saying? What are you using anyway, since you talk about"no custom shaders"? What is the default shader then?

And what are you asking to put in my shader? the separate shell thing? The way the reflections are calculated now is pretty much exactly like that, save for the second specular. Which you don't really need with reflection anyway.

bugworld

Oh no I'm not even using Xoliol's shader(I really wanted to, but I'm using this pathetic machine that any custom fx/cg shader makes it very hard to bring up the attribute editor.). I by no means was trying to push Xoliul to put anything into his shaders, I guess I misunderstood when he said "if I want two separate spec highlights I would need custom shaders" I thought he meant this was not included in his current shader.

But anyway, I didn't quite understand everyones' suggestions, seems that I should just put spec map for the fiber texture, but what I did was (firstly I didn't use any custom thing, just a phong or blinn)putting a layer of lines in normal map where I want the fiber material and just put spec for that area very high, so it's got this shinny bumpy shading look, as I found only using spec just wont cut it, it needs to have textual shading- as I found in games. But then the problem was there's only gonna be this shinny bumpy look, where the complete look includes smooth surface's spec highlight on top of it. Then I duplicate that area's poly, push it out a tiny bit, and just assign a shinny glass to it(of course with its original no bumpy normal map), and I got that layer of hightlight. Apparently my "theory" was a stupidly inefficient one Lol

I didn't post pics coz I haven't got anything worthy to show yet, but here they are just for clarification's sake. And the screengrab from NFS Shift.

JordanW

perna wrote: »

So, this thread.. lots of words.. where are the images? Everyone's so big on theory

Sometimes writing something a sentence or two is helpful enough and quicker than doing it for them :P

bugworld

Hey I hope your're not saying that I'm leeching technique here Perna? I believe I gave a reasonable amount of effort. I didn't quite get the separate specular theory, since the main problem I have is there're two different normal maps(I don't know how to associate each to its own specular highlights.). And I can't get into coding now to try other approaches. And I've post the pictures.
Any suggestions?

Xoliul

Hey bugworld, from what i can see:
-just don't use the normalmap (or tone it down a lot), the effect is really minimal irl, especially on the really shiny exterior carbon. They give that multiple layers of clearcoat so it becomes really smooth.
-tweak the spec values. Specular is so important, you can definitely get it beyond the shiny plastic look you have now by just playing with the specmap values.

Don't use the poly-shell method. It's a completely outdated method that shouldn't be considered nowadays. If you really wanna go the correct route, you gotta start using some shaders, otherwise just try and make it work with what you have; smoother surface, tweaked specular values, and take some of the yellow out of the diffuse. It wouldn't hurt to make the texture a 'lil bit higher res, as wel as get a better base texture, it should look more checkered than the diagonal lines you have now.

(hey and those flames don't look too good in such a bright red color)

bugworld

Thanks Xoliul, that's the answer I was looking for. Just the right approach. Should've post those pictures to clear things up at the first place.
Yeah the car is ugly and it's supposed to be ignored. I just needed to demonstrate the effect I want-bumpy surface underneath plastic shell(so I'm not sure why Xoliul you thought shinny plastic was not good?That's what it is isn't it?).Anyway the whole thing was just out of curiosity. I just wanted to know how to get the look they have in those games. For now I'll just stick to tweaking specs and ignore the normal thing.