blender 2.79/2.8 hair shader, subsurface

Tips, trick's, and links about computer graphics world

Moderator: joepal

blender 2.79/2.8 hair shader, subsurface

Postby jujube » Mon Sep 17, 2018 1:22 am

Posting it here instead of my "doodles" thread because it deserves its own thread, and also because it's not super makehuman related.. not sure where any of it goes...

I have a huuuuuuuuge pile of shader experimenting I did a few months ago that I didn't share yet.

Blender 2.79 development + version + 2.8 beta have a lovely principed hair shader similar to the one in renderman, plus a new option for the subsurface in the regular principled shader.

and yes, if you try very hard (or have a beefy computer) it really is possible to have hairs collide with things
Attachments
hair3.png
hair4.png
hair5.png
over 100% red
hairtests1.png
soft brown/blond hair
hairtests6.png
0% to 100% melanin
hairtests7.png
stray hairs
hairtests9.png
more than 100% red
hairtests14.png
red and non-red blond hair
Last edited by jujube on Mon Sep 17, 2018 1:24 am, edited 1 time in total.
jujube
 
Posts: 397
Joined: Fri Aug 14, 2015 10:46 pm

Re: blender 2.79/2.8 hair shader, subsurface

Postby jujube » Mon Sep 17, 2018 1:24 am

Hair part two:
Attachments
orders of magnitude.PNG
closer.PNG
rrrrrrr.PNG
0001.png
jujube
 
Posts: 397
Joined: Fri Aug 14, 2015 10:46 pm

Re: blender 2.79/2.8 hair shader, subsurface

Postby jujube » Mon Sep 17, 2018 1:26 am

More recently the voronoi finally has more modes, most excitingly a crackle mode! You can also do creepy things with it, which I put in an imgur album: https://imgur.com/a/pRKfQrb
(actually only the first two use creepy crackles, the rest are displacement subsurf using texturehaven files instead.)
Attachments
wrinkly freak thing.PNG
pretty crackle.PNG
noisy crackle.PNG
jujube
 
Posts: 397
Joined: Fri Aug 14, 2015 10:46 pm

Re: blender 2.79/2.8 hair shader, subsurface

Postby wolgade » Tue Sep 18, 2018 9:57 am

Interesting. Thanks for sharing your experiments. Especially hair collision looks promising.
wolgade
 
Posts: 722
Joined: Wed Jan 30, 2013 6:50 pm

Re: blender 2.79/2.8 hair shader, subsurface

Postby jujube » Thu Sep 20, 2018 3:18 am

Oh yeah that reminds me, here are the in progress views of the hair sim. (the hair physics is not a recent improvement though, I think. )
The physics settings, too.
Oh, and another strange thing, is that the ramped up collision quality didn't actually seem to make the hair truly rest on the collision object, it only delayed the inevitable, lol. IIRC the fancy hair would seem to rest on the object perfectly at first, but then eventually slowly fall through the object, the same way that low quality hair does quickly and immediately to attempted collision objects.
Also, child hairs have no collision, so the underside has a bunch of extra hairs secretly passing through the object.
Attachments
hairsettings.PNG
note the very high number of segments! I'm pretty sure it was just as, or more, important as the actual hair dynamics settings.
collidersettings.PNG
finally, satisfaction.PNG
invisible collision object + no child hairs
hairsim.PNG
less parent hairs + more child hairs = hairs passing through geometry
jujube
 
Posts: 397
Joined: Fri Aug 14, 2015 10:46 pm

Re: blender 2.79/2.8 hair shader, subsurface

Postby RobBaer » Sat Sep 22, 2018 1:26 pm

jujube wrote:Also, child hairs have no collision, so the underside has a bunch of extra hairs secretly passing through the object.


I wonder if this is a "bug" worth reporting on the Blender site? You already have a nice simple reproducible example. It seems at the very least a desirable "feature fix".
User avatar
RobBaer
 
Posts: 692
Joined: Sat Jul 13, 2013 3:30 pm
Location: Kirksville, MO USA

Re: blender 2.79/2.8 hair shader, subsurface

Postby wolgade » Sun Sep 23, 2018 8:21 am

RobBaer wrote:I wonder if this is a "bug" worth reporting on the Blender site?

As far as I understood the concept of "children", this is expected behaviour. Children don't know anything about physics. They don't get simulated. They're either interpolated between existing particles (Interpolate) or grouped around them within a certain radius (Simple).
wolgade
 
Posts: 722
Joined: Wed Jan 30, 2013 6:50 pm

Re: blender 2.79/2.8 hair shader, subsurface

Postby RobBaer » Sun Sep 23, 2018 4:07 pm

wolgade wrote:As far as I understood the concept of "children", this is expected behaviour. Children don't know anything about physics. They don't get simulated. They're either interpolated between existing particles (Interpolate) or grouped around them within a certain radius (Simple).

I guess you are right [ https://docs.blender.org/manual/ko/dev/ ... ldren.html ]
Children are Hair and Keyed particles assigned subparticles. They make it possible to work primarily with a relatively low amount of Parent particles, for whom the physics are calculated. The children are then aligned to their parents. Without recalculating the physics the number and visualization of the children can be changed.


I wonder if cranking up the parent's deflect emitter would help "simulate child deflection" at least with simple children. Probably wouldn't help with interpolated hair.

I still am totally incompetent at working particle hair to good result. I really like jujube's tests because they teach me how to step back and think about hair behavior from first principals. Usually, I just change settings and see what happens :o
User avatar
RobBaer
 
Posts: 692
Joined: Sat Jul 13, 2013 3:30 pm
Location: Kirksville, MO USA

Re: blender 2.79/2.8 hair shader, subsurface

Postby blindsaypatten » Mon Oct 01, 2018 8:49 pm

Wrt the shader, there is a good demonstration on youtube:
https://www.youtube.com/watch?v=xNlGsmZ6osk

Basically you can replace the sometimes insane network of hair shader material nodes with a single node that's easy to get realistic results with.

Oh boy would I love to buy a reusable form of the hairstyles in the demo!

Edit: here are the material nodes from Mindfront's African Hair with Bun, replaced by the single Principled Hair BSDF node:
AfroNodes.png


The difference in the renders is almost indistinguishable even without having gone to any extent to make them match.
blindsaypatten
 
Posts: 541
Joined: Tue Mar 14, 2017 11:16 pm

Re: blender 2.79/2.8 hair shader, subsurface

Postby jujube » Sat Oct 06, 2018 12:04 am

wolgade wrote:
RobBaer wrote:I wonder if this is a "bug" worth reporting on the Blender site?

As far as I understood the concept of "children", this is expected behaviour. Children don't know anything about physics. They don't get simulated. They're either interpolated between existing particles (Interpolate) or grouped around them within a certain radius (Simple).


Nah, this was before physics. Children have a separate thing where they have zero physics. The issue is that the base hairs do have physics, but it's buggy physics.

(The image is of hair with children, showing how child hairs ignore collision completely. I avoided it by taking all those renders from an angle that didn''t show the hairs passing through. But having a vertex group that put less child hairs on the parent hairs growing from lower on the rectangle, may potentially help. )

The video is of the hair dynamics without child particles. At the end of the video, the hairs start to pass through the cylinder.
Attachments
0001-0180.avi
(8.43 MiB) Downloaded 11 times
children.PNG
jujube
 
Posts: 397
Joined: Fri Aug 14, 2015 10:46 pm

Next

Return to Off topic

Who is online

Users browsing this forum: No registered users and 1 guest

cron