Control hair color along lenght

[jstrob]

Hi,

I know there is the Hairinfotex that make a gradient with a bias along hair length but is possible to have more control on the color along the length of a hair strand like with a gradient ramp? Or maybe using vertex painting?

I am trying to make a skunk tail like you can see here the tip is black and base is white but transition is sharper that what I can do with the vrayHairInfoTex...

and by the way I saw in the doc that hair have no diffuse (and we chouls leave it black unless the hair has dirt) so to get that color in the hair I would put the texture in the transmission alone [do I have to copy it to the specular too? or do I leave the spec linked to the transmission (in that case I guess the spec color has no effect anymore???)]

[Midiaeffects]

Have you tried to put your HairInfoTex into a Gradient Ramp in Mapped as gradient type? I guess it should work...

-Eugenio

EDIT: Just tested it and there's this little bug where it seems the first knot from the gradient is always black. To solve it I simply added another knot. And BTW, I can also use HairInfoTex inside an output map to control the transition with a curve...

-Somehow the first (red) knot is black


-Adding another knot seems to solves the problem. (but the bug is still there if you change bias in HairInfoTex, though).

[jstrob]

Cool thank s for the tip! I will try that it should work!

[jstrob]

I was not getting black tip, but I was getting some black stands, I just choosed planar from object XYZ as texture mapping type.




with rally no extra knot:

[Midiaeffects]

Hey, nice find jstrob! I actually forgot to mention the black strands! And I haven't found a solution for that! So thanks! And looks like my problem was that I tested in Vray 3.30 which I have installed in max 2016. I played with Vray 3.40.02 in max 2017 and indeed there's no need to add an extra knot. Cool!

Vlado, the black strands is surely a BUG. I keep re-rendering and the black strands are totally random every time. Downloading 3.40.03 to see if the issue persists.

EDIT: Tested in 3.40.03 and yes, black strands are there and appear randomly each time I fire a render.

-Eugenio

[vlado]

Do they go away if you turn off the tiling of the gradient ramp?

Best regards,
Vlado

[Midiaeffects]

I guess I've tried everything, but no, they keep showing. Turning tiling off in 3.40.03 (don't know about previous versions) instead of black, they show up as white. Gradient ramp always had some problems at the borders, often I have to use a tiling of 0.99 instead of 1 to get rid of it. Or setting blur to 0.01. But in this case it doesn't help.

At least is easily solvable by changing the Mapping to anything other than Explicit Map Channel.

-Eugenio

[jstrob]

Do they go away if you turn off the tiling of the gradient ramp?

Best regards,
Vlado

That's what I think of trying first but no here too. What's funny is that if I change the gradient ramp blur value, the black strands are not the same.

[vlado]

Then it would be best to post some example scene...

Best regards,
Vlado

[jstrob]

Really stange, I didn't keep my previous test and I can't reproduce the black strands bug. And now I got black tip for max hair and fur and black root for V-Ray fur. And even choosing another mapping doesn't solve the black tip this time.

here is a scene. http://www.phylacterecola.com/strob/...rVlado_001.max

[Midiaeffects]

That's interesting, opened jstrob file here on max 2017 Vray 3.40.03 and got black root/tips too. But if build a scene from scratch, it doesn't happen. Another thing is that I just get black strands from Hair and Fur, while VrayFur works fine.

Rendered 20 frames to show how the black strands appear randomly per frame:



And here's the scene file (max 2017):
FurFlicker.zip

-Eugenio

[jstrob]

I'm on max 2016 vray 3.40.02

[Miro]

Hi guys!
We've reported the issue with the black "flickering" strands to our developers and will post in this thread on any updates.

Regarding the black tips in jstrob's scene - these are coming from the second VRayHairInfoTex and its empty color A and color B slots, plugged into the Flag#1 slot of the gradient.
Unhooking that map or plugging something in the two texture slots should fix the issue you're having.

As a suggestion, for best results it is recommended to change the Hairs parameter to "mr prim" (Environment and effects > Effects > Hair and Fur) and plug the hair material in the "mr Parameters" rollout of the Hair and Fur modifier.

[jstrob]

Hi guys!
We've reported the issue with the black "flickering" strands to our developers and will post in this thread on any updates.

Regarding the black tips in jstrob's scene - these are coming from the second VRayHairInfoTex and its empty color A and color B slots, plugged into the Flag#1 slot of the gradient.
Unhooking that map or plugging something in the two texture slots should fix the issue you're having.

As a suggestion, for best results it is recommended to change the Hairs parameter to "mr prim" (Environment and effects > Effects > Hair and Fur) and plug the hair material in the "mr Parameters" rollout of the Hair and Fur modifier.

Ok great!

Nice find i didn't even notice I had a second texture in the gradient color. I saw it in the slate editor. In fact I didn't even know we could plug a texture in there. Nice to know. But I really don't know how the texture got plugged there. If I remove it the black tip/root are gone.

And yes about the MR prim, I forgot about it but I think that was causing the black strands in my first test. In my second test I used "buffer" and I didn't get the black strands.

To avoid those black strands we can also just not use any hairinfotex and just rotate the V angle of the coordinates of the gradient in buffer mode. the only problem then is that with vray fur we get a uninvited color at the tip. But it doesn't show if we use taper.


I would like to know what are the possible problems if we use buffer instead of MR prim?

Here is a scene where I could reproduce the black strands with mrPrim on max hairAndFur
http://www.phylacterecola.com/strob/...trands_001.max

[Miro]

I would like to know what are the possible problems if we use buffer instead of MR prim?

Lighting, motion blur and depth of field wont work properly, there won't be any shadows cast on other objects, etc.