This was a real fun one!

This one was fun!

Is there any reason why the rigid body solver (DOP) isn't respecting the collision point velocity? I have essentially a wrecking ball into a wall, and if I multiply up the collision's point velocity attribute, there's no change on the force of the impact.

I'm using a standard static object set to deforming, nothing special. I even tried adding it as an rbdPackedObject set to static Deforming, still no change upon point velocity increase

20.5.278

I'm trying to use the Vellum Minimal solver in DOPS, just because I find it faster, and it's what I'm used to. Everything seems to work as expected EXCEPT the SDF collision path. When I use it, I can see the SDF get added into the vellumobject in the geometry spreadsheet, and I can visualize it when I throw a SOP solver down and view that portion of the DOPOBJECT. However, there are no collisions occurring. I seem to remember it working in previous builds of Houdini, and I'm wondering if the current production build might have broken it.

yeah, for vellum fluid, I crank on pop drag force. Especially when I wanna accentuate the effect of viscous fluids... Which vellum handles so effortlessly I might add!!!

I'm trying to cache a fairly simple vellum fluid sim, and my cache stops prematurely and when I go into the DOPnet to ascertain the issue, I see the following error...


Error
vellumobject1 - /obj/JP_rippleSim/dopnet1/vellumsolver1/graph_color_constraints: Error: Invalid source /obj/JP_rippleSim/dopnet1/vellumsolver1/graph_color_constraints/geometry.
(Error: vellumobject1 - /obj/JP_rippleSim/dopnet1/vellumsolver1/ocl_neighborsearch_fluid: Error: /obj/JP_rippleSim/dopnet1/vellumsolver1/ocl_neighborsearch_fluid/neighborsearchcl1: NaN detected in particle position.).

I have an nVidia RTX 4090 Driver 551.86

Houdini Indie 20.0.672

This is for a deadline, and I'd really love to fix this because vellum fluids are awesome, and the only solution I can think of to get this delivered.

**SOLVED**
updated to the latest nvidia driver, there was one this week.

Hello all!

Using vellum fluids to sim some blood (super amazing solver), however, I've noticed that vellum uses surface based collision detection vs. volume based. If I birth fluid on a moving object, after it's initial velocity inheritance, it doesn't seem to inherit the velocity of the collision object. I end up having to create a popwrangle that transfers velocity from the closest surface, which doesn't seem as intuitive as say, flip, where it'll automatically grab the collision object's velocity. Is this the case? Or is there a phantom function somewhere I'm not seeing?

awesome, just what I needed to know! Thanks a bunch dude!

If I have a standard FLIP particle system from which I created using the emit particles shelf tool, to what node inside the particle_fluid obj do I attach a ROP output driver in order to geocache my sim while retaining all the necessary channels to create a whitewater sim?

Thank you for your help and I apologize in advance for the “newbiness” of the question. I'm really trying to gain some houdini traction and these little hiccups are really hindering my learning progress.