Houdini Hair transparency control

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Hey,

im looking at transporting some of our current workflows from C4D to houdini. One of the effects we use quite often is using c4d's hair system to render splines. We can create volumetric looking lines using this with a lot of control, in particular mapping transparency in 3d space along the vertical to create a kind of ‘core’ effect with falloff (see attached)

Is this possible using the current suite of tools and the hair material? I have figured out how to map along u but not v so far, and also i realize the standard setup is just to generate a strand that always faces the camera, whereas we need a more volumetric effect.

Im just looking to get a handle on whether this effect can be achieved, and how deep to go down the rabbit hole.

Any info/pointers much appreciated!

Cheers,

C
Edited by Bergerac - May 8, 2019 06:41:01

Attachments:
c4d hair 03.png (276.5 KB)
c4d hair 02.png (283.8 KB)
c4d hair 01.png (33.3 KB)

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Here's a better example of what im after (in houdini this time)

Im using uv texture to generate rows and columns - which works for the U, but obviously the V is clamped to 0.5 all the way along (as its just a curve, so i understand i cant generate a range for this)

So is there a way for mantra to do this at rendertime? Ive currently got this set up just using the width attribute to control the thickness, and using a standard principled shader to plug the U into to get the colour gradient on the curve. Hip attached if anyone wants to have a look.

Cheers,

C

Attachments:
uv.png (73.0 KB)
HairRender_01.hip (488.0 KB)

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So ive found out that mantra does what im asking for on the fly, no need for pre UV'ing - big shout to Matt Estela @ cgwiki who solves so many of my problems. If you aren't supporting his patreon, then go do it now!
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