Hi,

Noob here. I'm trying to create a sim where there's a belt spanning over 2 rotating wheels.
One of them is "powered" (rotates by itself) and the other should rotate because of the friction with the belt:



I've managed to set up the initial state with vellum drape and I've created a DOP network where Vellum interacts with RBD.
The powered wheel part and a belt that kind of follows the motion kind of works but I cannot figure out how to make the other wheel rotate. It's locked in space.

I've attached a .hiplnc with my current progress.

Can you help me with this?
Links, tutorials, official documentation or examples, everything is game.

Attachments:
wheels.hiplc (788.3 KB)

Vellum and RBD can't directly affect each other.

Vellum does have a shape match constraint, which lets you make pretty rigid objects, and they then play nice with the rest of vellum.

Had a play today between other tasks, its ugly, and well past the point of 'is it worth it?', as I reckon you could fake it with just expressions and some clever sop tricks, but anyway, its a start.

Curious if anyone else has better ideas here. The alternative is go the other way, build this all in rbd, do the belt as a chain of connected rbd objects, but I'll leave that for someone else to solve.

Attachments:
vellum_belt_drive_v02_hiplc.hiplc (1001.8 KB)
vellum_belt_drive.gif (2.7 MB)

Just for posterity I'm also posting results of my experiments with doing it via SOP-tricks-only-way.
I'm "simulating" belt wobble and "droop" (greatly exaggerated on the gif just to show that it's there) with some VEX and VOP.
It can even be adjusted in real time and all params are relative to the bounding box, which is pretty nice.



The belt animation itself is based on this tank track tutorial:

https://www.youtube.com/watch?v=x3aeEutYulw [www.youtube.com]

Attachments:
wheel_belt_drive_no_sim.hiplc (442.1 KB)
ezgif-4-53b6cd1453.gif (930.1 KB)

Attachments:
sops_belt_drive.gif (1.8 MB)
belt_drive_sops.hip (310.0 KB)