Damon Lavenski

Hello everyone,

I'm currently working on a simulation of a bowl of pasta, and the main issue I'm running into with Vellum is that the simulation will not settle down. It continues to bubble, simmer, and jitter with every interaction.

I've tried several things to calm the simulation down. For example, after getting the pasta noodles to settle into the desired shape, I used a Time Shift to grab a specific frame so I wouldn't have to deal with all the jittering and bubbling caused by the excess velocity.

As another test, I created a stack of paper that falls into a tree to see if I could reproduce the same jittering and bubbling behavior. I know the cause of this behavior is most likely related to the solver settings or constraint conditions.

I also tried using a Pin to Target Constraint, setting the stiffness to zero, and enabling Velocity Blend. I also increased the damping a bit, but unfortunately, this doesn't seem to have made any difference.

I've been a Maya user for many years and have used nDynamics for most of my career, and I've never encountered this type of behavior to this extent. Obviously, you can get some bubbling and jittering in nDynamics as well, but not nearly as much as I'm seeing here.

I'm fairly new to Houdini, so I'm hoping someone on the forum might be able to point me in the right direction and help me figure out what is causing this behavior.

I've also tried layering the pieces and assigning IDs to every individual piece of paper so that I could use the layering attributes, but I haven't had much success with that either.

Thank you in advance for any help!

thank you freshbaked for the help, I added a color SOP between my geometry and the attribute transfer SOP. set the color to black and that solved the issue.

I spent an hour with Gemini and check TBT if they could give me the correct answer. which you did so eloquently so thank you.

Hello everyone,

I’m a Maya user recently making the jump to Houdini and I’m currently setting up a Vellum cloth project. I’m trying to build a procedural "de-intersector" to clean up self-intersecting geometry (knees/elbows) before the solver kicks in. I’d like to keep this as "SOP-native" as possible with minimal VEX.

The Workflow:

I’m using an Intersection Analysis SOP to generate points at the self-intersection areas.

I then use an Attribute Transfer SOP to transfer @Cd (red) from those points onto my main geometry to create a mask.

I've verified in the viewport and Geometry Spreadsheet that the Cd and mask attributes are correctly transferring to the points on my main mesh.

The Issue: I cannot get the Smooth SOP (or Peak SOP) to respect this mask.

Things I’ve tried:

Group Field: I’ve tried using @Cd.r > 0 and @mask > 0 in the Group field. When the field is empty, the whole mesh smooths correctly. As soon as I add the attribute expression, the node does nothing.

Hard Groups: I used a Wrangle to set a point group: if(@mask > 0) setpointgroup(0, "fix", @ptnum, 1);. Even with the "fix" group selected in the Smooth SOP, there is no deformation.

Weight Attribute: I enabled "Use Weight Attribute" in Smooth 2.0 and pointed it to mask, but the smoothing strength doesn't seem to apply.

Manual Painting: If I use an Attribute Paint SOP to manually paint the mask, it works. This suggests my procedural mask from the Attribute Transfer is "invisible" to the Smooth SOP for some reason, even though I see it in the spreadsheet.

I know I could use a VDB/SDF approach, but I’m trying to keep my original topology/UVs intact.

Does anyone know why a transferred attribute would fail to trigger a Smooth SOP when a painted one works? Am I missing a step regarding attribute class (Point vs Vert) or precision?

Any suggestions or example files would be greatly appreciated!