Author Topic: Hair&Fur can't get color of hair from the base object  (Read 1308 times)

2019-12-07, 10:07:12

Bormax

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Hi
I'm trying to render a cat. I have textured base geometry and I'd like to use Hair&Fur modifier to cover it with hair. But if I apply H&F modifier hair take colors from the Material Parameters rollout of the H&M mod. I'd like to use Corona Hair material, but I can't make it to work. I use Max 2014 and there is slot called Apply mr Shader in mr Parameters rollout, tried to copy material there, but it didn't get UVWs from the base object and renders hair with some plain color.
It's possible to map Tip and Root color in H&F's material rollout, but parsing time for the amount of hair which looks good is terribly long - 19 minutes, if I convert hair to geometry parsing takes only 11 seconds, but I still have problem with mapping - all hair has plain color.
Unfortunately I didn't find any tutorial for tis case in internet. In all of the ones I found guys just apply some textured material to the base mesh and get hair rendered with the colors taken from that mesh. I don't know why it doesn't work in my case, but it didn't work with any objects and H&M mod. applied to them
« Last Edit: 2020-01-29, 20:46:59 by Bormax »

2019-12-07, 10:21:06
Reply #1

romullus

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You're not doing anything wrong. UV coordinates are not transfered from base object to hairs, when Corona hair material is used through mr shader. This is Autodesk's bug and Corona can't solve it. Your options is to disable mr shader and add texture to the tip and root colour slots or use third party hair solution, like Ornatrix.
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2019-12-07, 10:35:25
Reply #2

Bormax

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You're not doing anything wrong. UV coordinates are not transfered from base object to hairs, when Corona hair material is used through mr shader. This is Autodesk's bug and Corona can't solve it. Your options is to disable mr shader and add texture to the tip and root colour slots or use third party hair solution, like Ornatrix.

Thanks romullus. But what about converted to mesh hair geometry? 19 mins of parsing is really much... Is there any solution for that?

2019-12-07, 10:55:49
Reply #3

romullus

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Never tried that. My guess that it should transfer UV coordinates, but if it doesn't, then it's purely Autodesk's fault.

Strange thing, i never noticed that adding texture to the tips and roots colour, would add to the scenes parsing time. Need to test it.
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2019-12-07, 17:02:48
Reply #4

Bormax

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These are some of tutorials I found.
In both of them guys just assigned material to the base plane and got hair colored by the material's defuse texture.
If I do the same I always get attached result.

2019-12-07, 17:30:31
Reply #5

romullus

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This is old Corona, back then there were no such thing as Corona hair, and H&F was rendered as geometry. Now we have hair material, which looks much better, but unfortunately it can't get UVs from H&F :[
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2019-12-08, 12:32:36
Reply #6

Bormax

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2020-01-29, 05:33:10
Reply #7

tahir1983

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Its very interesting what  prevented  from being left geometry mode rendering  even for simple corona material as it was before (corona 2)

2020-01-29, 18:23:30
Reply #8

maru

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This is something we are aware of and we have it logged in our bug tracker. Hopefully we will be able to implement this soon.

Currently the workarounds include:
- Use 3rd party plugins (Ornatrix or Hair Farm) - this works out of the box
- Use "root color" and "tip color" slots in Hair&Fur - this works and maps the texture correctly, BUT disables any controls which are possible with the Corona Hair Mtl or any other custom shader (such as reflectivity, melanin, etc)
- Use world-space mapping or triplanar mapping, however this isn't always possible - e.g. in case of moving objects or objects which are not flat shapes

This is also possible to do in V-Ray and Arnold, but in Arnold requires workaround:
https://veda3d.com/arnold-with-hair-and-fur-modifier/

(Internal ID=216944008)

2020-01-29, 19:27:12
Reply #9

romullus

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This is something we are aware of and we have it logged in our bug tracker. Hopefully we will be able to implement this soon.

Does that means that there's a light in the end of a tunnel? That would be very good news indeed!
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2020-01-30, 11:58:50
Reply #10

maru

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This is something we are aware of and we have it logged in our bug tracker. Hopefully we will be able to implement this soon.

Does that means that there's a light in the end of a tunnel? That would be very good news indeed!

There are ways to make it work in other renderers, so why not Corona? :)

2020-01-30, 12:25:17
Reply #11

Fluss

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There are ways to make it work in other renderers, so why not Corona? :)

Let me grab a screen of that sentence for further use :)