physx collision won't stop

[jasond240]

First time using this amazing plugin and have what seems like a really simple problem with physx collisions... I'm simply dropping particles into a box but can't get them to stop moving.

I've searched the forum and added the suggested physx switch > kinematic but the particles still jitter a small amount way past when they should be stopped.

Here's my setup:

birth
position icon (surface)
speed
shape
physx shape (box)
physx collision (mesh) restitution 0.15, static friction 1, dynamic friction 1 (++ friction in case that was the problem)
physx switch (kinematic since sleep is disabled)

Any pointers here would be great!

Thanks
JD

[tyFlow]

Can you attach a video of the issue?

[jasond240]

No problem. See below using tyflow v0.16077.
 

I also noticed that the particles are going through the box as well for some reason. Its set to hull type > mesh.

I checked a similar example from this forum called Ice_cubes.max and the jittering happens in that file as well long after the birth and collisions stop. If you scrub the timeline way past when it should end, you can see it still calculating the tyflow.

Thanks a ton for looking at this!!

[tyFlow]

What is your sim time step and PhysX substeps set to?

[jasond240]

time step: frame, scale 1.0
physx substeps: 6

[tyFlow]

Decrease your time step and increase the PhysX substep count

Try 1/2 and 12.

[jasond240]

That helped! They are much less jittery and don't go through the box now but the pieces still move a bit a few hundred frames after it should stop. If I scrub 1000 frames later, tyflow still calculates and bogs the scene down. Should it still be trying to solve it so long after it completes?

Ouch, potentially found a problem. I'm moving the box 500 frames after the collision and even though the physx should be stopped, the particles are reacting to the G forces from the box being moved. Amazing how the they react but not desired here.

Thanks!

[tyFlow]

There is no "end sim" (see: halting problem). However, you can use the retimer to constrain playback to a certain set of frames, so if you want the sim to go from frame 0-100, set a linear curve on the retimer frame value from 0-100. tyFlow will then playback those frames and not sim past 100.

Also if you're setting particles to kinematic, don't forget to put a Stop operator on them too, to kill any residual velocities/spin.