How Do Games Render Fur?

It's easy to understand why fur is extremely problematic with its high density of objects and physical complexities, but somehow games have been rendering it for years! How could something so complex be so easily simplified?

Topics covered: Hair and its rendering complexities, shell texturing, half lambert, shell texturing applications, limitations of the technique, and overdraw

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Music:
Afternoon Break - Persona 3 OST
This Mysterious Feeling - Persona 3 OST
Midori Eyes - Paradise Killer OST
During The Test - Persona 3 OST
Junes Theme - Persona 4 OST
Every Day Is Night - VA-11 Hall-A OST
Underground Club - VA-11 Hall-A OST
Those Who Dwell In The Shadows - VA-11 Hall-A OST
Your Love Is A Drug - VA-11 Hall-A OST
GO!GO!STYLE - Paradise Killer OST
Joy - Persona 3 OST
Sandgem Town - Pokemon Diamond OST
Like A Dream Come True - Persona 4 OST
Layer Cake - Persona 5 OST
Prof. Omochao - Sonic Adventure 2 OST

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This video is dedicated to my friend, Alotryx.

#acerola #graphics #gamedev #unity3d #graphics #shaders

[julianlanty]

I imagine Acerola in a party corner like "they dont know how to render realtime hair"

[m_remon]

God I just realized he's wearing more layers as time passes.
Amazing.

[MrNyagasu]

I'm just going to take a picture of my dog, put it on a simple square mesh and call it a day.

[AB-Prince]

one technique I've seen to hide the gaps between shells, is to distribute the shells such that the gaps are bigger at the bottom and smaller near the top. as the denser lower layers do a good job of masking the gaps but the upper sparse layers need denser layers to hide the gaps

[SaadTheGlad]

These videos are genuinely one of two things I look forward to on YouTube, the other being Sebastian Lague videos. Great stuff.

[IzzyIkigai]

A game with a protagonist with amazing hair where everyone is bald and tries to kill the protagonist... You mean... Bald'ers gate?

[evilotis]

1:40 "a game with a protagonist with a beautiful head of hair but gets [transported?] into a universe where everyone is bald and is trying to kill them with having hair" and that was how Acerola made his fortune

[puckchang]

Viva Piñata’s grass may be just a visual trick, but you can’t imagine how much I wish I could just lay down in it. It always looked so soft! You can tell me that I need to go outside and touch grass, but the only thing I really want is to touch THAT grass!

[LanceBerylDev]

Nintendo particularly has really gotten really good at shell texturing across a ton of their recent games, particularly with the rendering of fur on characters like Donkey Kong. Fun fact: Super Mario Galaxy 2 (for Nintendo Wii) was originally going to make prolific use of shell texturing for its grass; which was showcased in various early development/promotional screenshots. -However come release, nearly all shell texturing was removed from the game. Why this was done I don't believe was ever specified.. it may have well been due to performance or technical complications, ..though personally I believe the more likely answer is that the team saw the effect as too uncanny applicated in this specific instance, and jarringly dissimilar from the presentation of grass in the first game, so it was scrapped (outside of a few one-off planetoids.)

[congobongoproductions]

Can't believe no one is mentioning this bit at 19:35 saying "...what's basically a layered cake of meshes" while "Layer Cake" is playing...

Masterfully done 👏

[tsbohc]

Oh, so that's why Sif is like that. Might be just me, but the uncanny look of the fur actually makes Sif look almost ethereal. I bet you could use this to intentionally trigger an uncanny valley effect when designing some otherworldly creatures. Neat stuff!

[scarletcafe]

I'd like to also say about the Half Lambert solution - one of the reason it works so well is because hair is, as you say, transmissive. Real hair has light pass & refract through it, so any part of a contiguous set of hair that is in total darkness will look really weird since it's nearly impossible in most situations with a light source. Half Lambert fakes the indirect lighting you would get from a path or ray-tracing lighting model even in a forward rendering environment, so it feels more natural.

[Superhirn]

I actually don't understand that much of what you say but it's just fun to see you magically combine values into complex lighting models (:

[_OpenJournal_]

This has become one of my favorite YouTube channels. I don’t have any interest in creating games or other things that require real-time rendering techniques, but I have a deep love for video games (although I don’t really play anymore). 30 minutes of extremely well articulated, concise, funny, and entertaining explanations to technologies and concepts I knew nothing about draws me in. This is what the internet was made for: experts of their craft sharing knowledge publicly. Even if I’m not going to internalize this information so that I can create with it, it’s beautiful to learn about the foundation of how things work and it brings me happiness. Keep sharing mr. Rola! You’re inspiring!

[nickybakes]

Our game, Steel Heel Jam, has a non rotating, almost top down camera, and while watching your live streams I realized this would be a cool addition to the environment art for some grass. I plan to easily add some basic vertex animation with a noise texture for wind on the grass.

[juanalbano]

Planet Zoo has an amazing fur system too for LOTS of animals. I'm not totally sure but it also looks like shell texturing, but it looks good even on grazing angles!

[JohnnyOlBoy]

I know next to nothing about graphics programming but these videos are always so entertaining

[DracoTheBlack]

Brave of you to assume that I've only watched four videos about rendering grass.

[flux]

24:43 THIS IS THE REASON why old Dark Souls bosses with fur brought my laptop always to lagging when i moved the camera close in ! Now i finally understand.
It never made sense to me that when the camera got stuck on the groin of the taurus demon that my pc almost crashed.

[morgan]

17:23 another way to do this is to lerp between last frame’s value and the whatever new value by some small amount. technically it’s dependent on the frame rate so maybe do that in the physics update and then a bit of smoothing in the per frame update, or calculate it every time. the benefit of this tho is that it’s an exponential approach, which feels very natural. it’s a first order lowpass filter, and eventually i’d like to make a video going thru it in depth because it’s a really good way to smooth things and i’ve been using it a lot in my game to make things smoother, and i think more people should know about it for game use.