Dynamic Fire Hose - Vellum

[FilipHodas]

Hi guys,

 

I'm fairly new to houdini and I got stuck on a sim and hoped you might be able to help.

For past two weeks I've been trying to create a dynamic fire hose - something like this. It seemed like a very simle task - vellum cloth hose somehow attached to rbd metal connector - but I just can't seem to get it to work properly.

In the scene I'm working on the hose should float for a bit with some turbulence and interact with other rbds floating around and then fall to the ground and hit floor collider+other falling rbds objects.

I'm using strut softbody in vellum and it seems to work pretty ok out of the box. The folding on the ground doesn't look that great, but thats probably just a matter of tweaking the settings. I managed to add some turbulence through the windforce node in DOP network.

I wanted to figure out how to constrain/attach the end of the hose to the rbd connector. At first I tried using vellum attach to geometry and set the max distance parameter exactly as I needed. That worked great with static geo, but didn't work at all with rbd object. Not sure if vellum is incompatible with rbd, or if I just set it up incorrectly - I used shelf too RBD object and connected it through the dop import to the third input in vellum attach to geo node.

When this didn't work out I thought I might be able to get away with merging the hose and connector into one obejct and then paint a mass and stiffness maps, so that the hose is soft, light and will fold on the floor, but the connector will be stiff to the point it will behave like RBD and heavier than the hose, so that it would pull it down.

I created primitive stiffness attribute and then painted a map - the hose is black and the connector is white. In the vellum constraints I set both bend and stretch stiffness to scale by attribute and was expecting that the hose stiffness would be multiplied by 0 and thus would pretty much collapse on collision, while the connector would be scaled by 1 and the stiffness would be according to the stiffness value. But when I use scale by attribute the entire object gets completely flattened on collision and there is no difference between the connector's and the hose's stiffness at all. Also I was unable to find a way to adjust mass with attribute, so I'm not sure if this is even viable solution to my problem anyway.

How would you approach something like this?

TL;DR: What's the best way to create vellum hose and attach one end of it to moving rigid body with mutual interaction?

EDIT: I managed to get the stiffness map working on a dummy scene, but still didn't figure out how to adjust mass by attribute/group. Is it even possible?

Apologies in advance if it's something really simple and obvious!

Thanks for any help!

 

 

Edited July 3, 2019 by FilipHodas
Updating the post