How is animal fur made for modern (AAA) games

kaigonathus

With this I mean both long fur and short fur.

Here is a picture of a squirrel from rdr 2 and it seems that the fur is using some sort of shader or something like that? I have seen similar fur in other games, its weirdly fuzzy and kinda dotty.
https://www.reddit.com/r/reddeadredemption/comments/dtjnja/best_thing_about_the_photomode_we_can_finally_see/

Here are some short haired horses from Ghost of Tsushima, Im pretty sure that the fur is either sculpted in with stamps or textured that way. Tail and mane are made using hair cards right?
https://www.artstation.com/artwork/R3aVam

Then here are some dogs from The Last of Us 2, how about them. The fur seems to be way longer so it would need more detailed stamps and as they follow the form it kinda seems that it might have been simulated and then baked down. Is this a common practise, I mean if you truly want very detailed short fur, it might be the way to go? 
https://www.artstation.com/artwork/ELV34K

Is there something more to this? Is there cases when the whole animal would use hair cards instead of these shaders? I would love to know more about this  

oglu

Take a look at the Unreal fur demo. You can download them.
https://www.youtube.com/watch?v=0ixtpcqb85I

Neox

1. from red dead is called shells http://forums.cgsociety.org/t/character-wip-klonoa/907883

2. is just hair hair planes/cards, possibly actually groomed hair rendered down to a texture with alpha. could be painted as well.

the body is likely just texture and maybe a bit of a fresnel shader

3. does also look like cards to me.

http://wiki.polycount.com/wiki/HairTechnique#Hair_Technique_Examples

what oglu showed is possibly how it will be in the future. it's pretty expensive still, but does get optimized and is already a lot faster than months ago. you can striaght up groom your hair like you would in movies and bring that over to the engine as individual strands.

thomasp

Baking a groom down to a character and blending that with strategically placed haircards is what seems to have been done to those naughty dogs indeed. These are probably pretty low poly models.

Another way that only looks good on longer/dense fur and requires a lot of polygons is to cover everything in haircards. There are some dogs/wolves in FF15 that show that technique. Best to still have a groom baked down underneath though.

gnoop

oglu said:

Take a look at the Unreal fur demo. You can download them.
https://www.youtube.com/watch?v=0ixtpcqb85I

Looks like they have so huge budgets they are not sure what spend it  for so  they are willing to do kind of conveniences  for movie director.   

  It recalls me a project I worked for in 1999.   We did everything in  nowadays  2048x2048 resolution and super detailed lod01   because we seriously believed  a new generation of hardware is right behind the corner and will be available in few years we will finish our project.    Than we had to re-do evrything from scratch.

thomasp

Seems like a good thing to me to push the envelope. Going with grooms is the logical next step. I'd rather have this tech performant and ready in a freely accessible engine and after years of improvements rather than everyone cooking their own and offering raw 3rd party solutions when it suddenly becomes becomes the new standard.

But yes, they do like their movie studio PR and giving off the impression that you can just put something as complex as that in an actual game now, don't they. I always end up groaning rather audibly when there's talk about game-movie workflow convergence. But hey, if not this time around - next generation for sure!

poopipe

no haircards or grooming here..

thomasp

Lets hope it doesn't look like an obvious shader trick up close either. No way to know though...

gnoop

I recall I read a description of so called "fin" shader  in one of Nvidia GPU gems or something . Not sure where.  We never tried to do something like that for real and I haven't understood a half of the math there.

The idea was to use heigh channel in surface texture and spawn  small polygons  on geometry outlines  based on view vector/normal dot product . Those polygons would have alpha and make a silhouette  while other part of surface would have just baked in surface textures with couple shell layers up close or a kind of SSS style cheap trick to soften the lighting  . 

  Could be used for fir my guess.    The proper light interaction would still be an issue  probably.

 

poopipe

thomasp said:

Lets hope it doesn't look like an obvious shader trick up close either. No way to know though...

On the chimp?..
You have to get pretty close before it breaks down - beyond the point where geometry and textures fail.

 It's fundamentally the fin and shell method if you fed it a combination of meth, steroids and ritalin.