Edmond Boulet-Gilly

Thank you both for all those info.

Using the S coordinate is quite a good idea, at least to scale the curve down, which is very interesting for me.

I managed to get it work in Mantra but no luck in Karma so far. Out of the 2 parametric coordinate (s,t) only t seems to be working, s is just returning a black value.

I will keep digging in that direction.
Thanks !

it's on old post but I will bump it, I am facing a similar issue :
https://www.sidefx.com/forum/topic/88235/?page=1#post-381069 [www.sidefx.com]

Hello,

I have been trying to drive the width of a curve from a material when rendering with Karma.

I know the usual workflow is to put a 'pscale' attribute (or a 'width' attribute) at SOP level.
But I was hoping to use a bind node to import that attribute inside material builder, modify it in some way (like have the width react to light or camera distance at render time) and then use a bind export or parameter node to send it to karma.

But so far it seems that the pscale attribute is not even accessible from a material builder when using karma. And I could not find a way to export it to the renderer.

I have attached some of things I have tried, hope it helps.

Does anyone has ever tried that ? Or has some idea on how to proceed ?
Any help appreciated, thanks !