User avatar
By stir
#389417
Hey i got another question related to hairfarm.
I have a bad feeling it might be the same issue as stated in this thread.

http://www.maxwellrender.com/forum/view ... 00&t=43905
about the thickness map.


This problem is about the maps applied to the hair and how it is getting uv mapped.


Image
Image


As you can see from the image Maxwell ain't respecting the underlying color.
while scanline is mapping this correctly.
I think it might be doing the same as with the thickness. it samples 1 and put the same values on the rest.

Can some one help me confirm my theory?

Cheers
-Mats
User avatar
By Mihnea Balta
#389420
If you have vertex colors for hairs, you need to apply a Maxwell material which is using a white texture on the reflectance 0 channel in order to see the colors. The refl0 texture will be modulated (multiplied) by the hair colors. Note that setting the refl0 color to white won't work, you need to use a texture. This is sort of a hack inside Maxwell, since vertex colors aren't really supported in the rest of its rendering pipeline.

See this section of the documentation for more details: http://support.nextlimit.com/display/mx ... Max+-+Hair (it describes the built-in Hair modifier, but it applies to HairFarm as well).
User avatar
By stir
#389439
thanks for the feedback.
I get prompt with a login when i use that link?
neither the maxwell forum login or the nextlimit gateway login works.

Also, i don't use vertexcolors so i don't think that workaround work for this case. but indeed a good thing to know about!

BUT! a good workaround is that hairfarm have a "Convert hair to poly" i put that on the top of the stack and ask it to only convert at rendertime. that way i get the speed of the hair display in the viewport, then it bakes down all the parameters including UV, materials, sizes and lengths! Making it no problem for maxwell to handle.

The conversion might have some drawbacks that i don't know about yet, but right now it works for me.



Cheers
-Mats
User avatar
By Mihnea Balta
#389441
Sorry, viewing that page in the documentation was restricted for some reason. I fixed the permissions now.

If you're not using vertex colors, I'm afraid I don't understand the problem. Are you simply trying to map a texture on the hairs using the root UVs generated by Hairfarm? This should work, but please keep in mind that root UVs are on channel 1, not 0. Channel 0 contains lengthwise UVs (i.e. U going from 0 at the root of each hair, to 1 at the tip).
User avatar
By stir
#389443
Yes
Its just a texturemap applied. and i want it to map corresponding to the underlying UV

Here is a image with the checkermap applied
Image

and we can see it is mapping with the lengthwise UVs. white at the bottom black at the top.

as you say channel 0 is lengthwise UVs and channel 1 is root uvs

the thing is, in 3Ds max the uv channels starts at channel 1 and not channel 0.
and since channel 1 acted like lengthwise UVs, i just assumed the numbering was offsett and i could use channel 2 and it whould works as your channel 1.
so i tried switch to channel 2 and this just gave me the UV error when trying to render.

ERROR... bla bla material contains channel 2... bla bla model don't have that channel bla bla





Just to clerify:

Here is the result using the conversion method, and it yields the result im looking for

Image

so what we are trying now is to get this result, without needing to convert the hair to mesh.


Cheers
-Mats
User avatar
By stir
#389445
here i tried another test.
This time i made a maxwell ref material.
clicked "NEW" and made a new .mxm file on the disk.
then clicked "Edit" and opened the mxm editor.

Inn here i applied the checker texturemap as i have done previously. Only innside mxm editor i can map to channel 0 and channel 1.
So i tried channel 0 first. as expected this mapped it along the length UV


Image



I then changed to channel 1.
I did not get any channel error when sending this to render so there must have been a channel there present. but the result was not as expected



Image




Cheers
-Mats
User avatar
By Mihnea Balta
#389446
Ok, there seems to be a problem retrieving the root UVs from HairFarm. I will look into it and let you know when we have a fix.

Just to make sure we're on the same page, you're applying the hair material on the hair modifier, not the base mesh, right? There's a Material rollup in the parameters panel for the "Hair Generate" modifier, where you can apply a material for the hair itself. In that case, using channel 2 for a texture should work, you don't need to use a referenced MXM material. You will only get the error about not enough channels if you apply the material to the base mesh, since your base mesh most likely has only one channel.

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