Hair Width Taper on V-Ray proxy.

[jgriffin]

I'm generating fur with XGen and caching to Alembic, then reading in the alembic using a v-ray proxy. I've got everything working and rendering beautifully except for the taper of each hair in the v-ray proxy. I've tried driving the "Hair Width Multiplier" attribute with the "DistanceAlongStrand" value from a VrayHairSampler but the hair width just drops to zero. There's got to be a way to control hair taper, here. What am I missing?

Thanks!

[kagemaru]

I tested between 3dsmax and Houdini, but applying the same concept, variable width along the strand.
It works perfectly if you manage to put an attribute called "width" on the exported knot of the hair. I can't help you on how to do this with maya/xgen though, sorry.

[vlado]

Can you post an Alembic file generated in this way? Perhaps the width parameter is called differently from what we expect in the V-Ray proxy.

Best regards,
Vlado

[jgriffin]

Sure thing, Vlado.

(edited to change to dropbox link. The other link wasn't working properly)

[jgriffin]

Thanks for looking into it, kagemaru! There's a width attribute but it appears to be a static value without the taper applied.... Not sure about putting that attribute per-knot either. This is my first time using XGen in production and I've still got a fair bit to learn.

I was able to drive transparency with DistanceAlongStrand and that may be good enough for this project. The render is a bit softer than with true taper but on medium and wide shots it's not noticeable.

[kagemaru]

Thanks for looking into it, kagemaru! There's a width attribute but it appears to be a static value without the taper applied.... Not sure about putting that attribute per-knot either. This is my first time using XGen in production and I've still got a fair bit to learn.

I was able to drive transparency with DistanceAlongStrand and that may be good enough for this project. The render is a bit softer than with true taper but on medium and wide shots it's not noticeable.

Well if you can use opacity, that's always better but it really is heavier to render.
I'm pretty sure there'll be a way to export that attribute, in some ways you already have it if the DistanceAlongStrand it's working. The difference i think lies in the geometric properties against the shading one. I think though it would be cool to access and manipulate width afterwards in the vrayproxy (same concept for particle as well) so we would remap and adjust stuff on a per-shot basis instead of re-exporting.