Most effective way to do fur

Makkon · Nov 2006

My mentor has asked that I finish one of my older characters for animation. This particular character's body is completely covered in fur, but I want the fur to be fuzzy and clean, devoid of any visible seams. Ive tried a number of methoods, none of which have given me decent results (often resulting in seams, messy UVs, or messy geometry). Currently my character's fur parts have conflicting normals, resulting in extreme errors. I was curious if anyone here has any experience with working with alpha-fur. If so, what techniques wield the best results? What has worked, and what hasn't? I'm all out of ideas. Thank you.

fritz · Nov 2006

i've been struggling with this for a while....and after lots of trial and error i'm slowly starting to get there. i don't know if you are familiar w/the shell technique or not, but it works. it's how they did the fur in shadow of the colossus. this is one read that i found pretty good. i wanted more of a straight forward tutorial on it....but after reading this you get the gist of it

http://www.xbdev.net/directx3dx/specialX/Fur/index.php

Daz · Nov 2006

I was going to mention the shell technique, but fritz got there first. I cant find the making of article, but it seems to be cached without images: http://72.14.253.104/search?q=cache:GwhI...t=clnk&cd=5

But anyway, the toughest issue you're going to face, is alpha sorting (although If you can pull off the shell technique thats not so much of an issue, since youre pretty much always sorting back to front) So what engine are you putting this character into? Things to note: alpha test is much easier for engines to sort properly than alphablending. i.e hard versus soft edged alpha. Completely correct alpha sorting is still computationally expensive, which is why so many games stll use alphatesting as opposed to blending for stuff like grass, hair and fur. Even GoW hair is alphatest, and that's cutting edge software on (kinda) cutting edge hardware.

How you do this somewhat depends on your engine of choice.

edit, also check out the downloadable FF models. They give great hair.

fritz · Nov 2006

here it is w/the pics....it's in question mark....i mean japanese tho.

http://www.watch.impress.co.jp/game/docs/20051207/3dwa.htm

i guess...now that i think about it...you mentioned that your char is completely covered in fur. this would probably be a pain in the rump using the shell tech as far as animation is concerned. by all means tho, if you figure something out that works....please share. this crap has been drivin' me nuts for a while now.

Makkon · Nov 2006

My main concern is that shelling uses a lot of polys, if I'm not mistaken, taking a huge toll on the performance of an engine. My character stands at about 4600 polys, barely within the limit of the engine for a character. I also am not fond of the dotty/spaced look that shelling gives to fur. I'll still give it a try, maybe it'll work out better than I thought.
As for the FF models, where can I download them? I'd like to be able to view the alpha maps and how the geometry is attached, that may answer a few questions.

Daz · Nov 2006

http://boards.polycount.net/showflat.php?Cat=0&Number=77520&page=0&fpart=1&vc=1

Makkon · Nov 2006

Hmm... seems he removed the obj exporter. That would have been nice to have, I could view the flats with that.
As for the fur, progress is being made. I discovered the lovley "normals" sub-section in the edit-polygons drop-down in which I can repair odd normals. It does a mighty fine job, too. The geometry is set, now for the mystery of unwrapping it. I may have to supply a screen shot to make things more clear, but I'm a little fuzzy as to how I'm going to pull this off. I'll get back to you in a bit....

thomasp · Nov 2006

re: shells - there is a fx shader downloadable somewhere from nvidia that does this on solid geometry. means you don't have to actually model the shells yourself. it's apparently not too expensive to render either (one pass).

Makkon · Nov 2006

That probably does parallax shading, I would think, a new method that is not supported by many graphics cards. But if you can find it, link me. I would love to give it a try.
Well, I don't have my model with me... so I made a terrible illistration.

The extruding surface is suppsed to be the part of the fur that will have a transparancy. The yellow lines are normals. When I do this, I can avoid messed up normals and have a smooth transition from main mesh to fuzz, including the texture. The craptacular grid thing with a mouth is an example of the UV map. The geometry that goes beneath the fur does not need a lot of detail, and will suffer from severe distortion. But, the texture will be basically seamless... I hope.
I'll post a test soon.

Most effective way to do fur

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