Drive Vellum Parameters with Attributes

[arcus]

Hi, 

I am trying to control the rest length scale of a vellum sim with an attribute I created outside of the solver upwards in the stream. I managed to get it into the solver via a sop solver and attribute transfer but now I am struggling to connect that to the rest length scale. The vex field in the vellumconstraintproperties is not working for me, or I cant figure it out. 

 

Cells_v04.hipnc

[hannes603]

vellum restöength_simple.hip here an example how to work with vellum prop to import animated attrib. 

[arcus]

Hey Hannes,

thanks for your reply and taking the time, very helpful already! I found out its not working because of the group I put in vellumcosntraintgeometry node. The thing is I wanted to animate the rest length scale of the pressure constraint because it behaves differently to the cloth rest length. But thats causing the problem.
I believe the pressure rest length is treated differently from the cloth one. It works for manually animating it though. Do you have an Idea if that's just a limitation or if that's possible otherwise? 

I updated my file. It works as intended as long as you don't turn on the group for the vellumcosntraintgeometry node.
 

Cells_v05.hipnc

[hannes603]

your scene is erroring here. i think i have a different h version..   what kind of effect you want to achiev ?

[arcus]

oh shit ok, I am using Houdini 21. Can you open it at all or is something inside erroring? The basic effect I want to achieve is a sphere (balloon) inflating inside another one as soon as it gets the infect attribute which is cretead by particles approaching it.
I uploaded a video. I hope that makes it clearer ^^. There I animated the green ball inside the white ones with keyframes. This works fine with the pressure rest length but the plan would be to have those smaller balls inside all the other bigger ones. That's why I want to drive it with an attribute.

 

[hannes603]

Cells_v06.hipnc i mean the pressure group works in a sop solver. also the infect attrib works on the small ball.. guess you had too less stiffness on the pressure constraint to noticed the effect.   also you need to trasnfer the impact to the small ball right..   looking cool so far

[arcus]

Thanks! Looking good. I also tried transferring the attribute before the sim but the problem I had with this, is that doing it this way results in a wrong timing of when the inflation happens. That's why I tried doing everything inside the solver. You can see it on the yellow merge you added. Since the small sphere is intersecting it gets the attribute earlier than it would during the sim. This results in it inflating to soon, although its technically not close enough in the sim. Does it make sense? xd

 

But in general that's working now, so thank you very much!

Edited 9 hours ago by arcus

[hannes603]

Cells_v08.hipnc  

   

you need a class or name attrib where you trasnfer the infect attrib from. you can also do it inside the solver  but in thisd example i did it outside maybe its easier to see

 

[hannes603]

Cells_v09.hipnc    sorry i forgot to convert the source points to centroids  plus i  didnt plug the class in ptnum in point import inside the vop..     it was just working bec the ptnum was the same .. now it works also with different ptnum (inside outside spheres)   here is the correct one  i marked the new nodes in red.