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So I'm trying to make particles bounce a bit on a surface before coming to a complete stop, like this:

enter image description here

The problem is that if the surface has any kind of incline, the particles will start to slide regardless of collision settings on both the collision object (plane) and the particle system, shown here:

Flat plane rotated by 1 degree

Plane with random variation

Collision settings used for the planes:

enter image description here

It's acting as if the friction is set to 0.99 or something, and never 1.0. So far I've tried increasing stickiness, damping, particle damping, particle drag, and decreasing the weight of the particles themselves. All of these settings can't seem to get rid of the sliding effect. I also tried looking this up but all posts with a similar issue were fixed by increasing a setting I've already tried with several different combinations with other settings.

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    $\begingroup$ Increasing the Physics > Integration > Subframes values and/or decreasing the ... > Timestep value helps a bit. But the particles still wander around, especially when the ground plane is tilted even more or the simulation runs longer. I don't know why... $\endgroup$
    – Blunder
    Commented Mar 20, 2022 at 18:31
  • $\begingroup$ Yeah that does help slow it down but never completely removes it. Increasing it to like 10-20 seems to be the sweet spot, cause anything higher has diminishing returns with loss in performance. Could this be a bug? $\endgroup$
    – spyro
    Commented Mar 20, 2022 at 21:54

1 Answer 1

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Objective - (Blend file below)

Have particles falling onto a heavily sloped object, bounce and slide a little but eventually come to a stop.

NOTE - In the Blend file the particle cache is set to 'External' to reduce the filesize. It won't work until that box is unticked.

Three sloped objects are used -

. The uppermost, an invisible sloped plane with Collision physics.

. A Very small distance under that another invisible plane, again with Collision physics.

. Under those, a (flattened) and visible cube with no physics.

All three are sloped at the same angle.

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The Uppermost plane -

...is called 'Catcher' and has both 'Damping and Friction' sliders set to 1.0 . That slows the particles down when they land and slide lazily downhill.

It's 'Permeability' slider is set 0.05 so most particles will be caught and slide but eventually fall through onto the plane under that, the 'Underlay Catcher'.

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'Underlay Catcher' -

This one is set to Kill particles on contact and it's Permeability is set to zero, so none fall through.

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The Visible sloped cube -

This is scenery only and placed a little under the underlay catcher so particles won't be seen 'sinking' into it's surface.

.

The Emitter -

... is set to render dead particles so we see them land, slide a bit and stop but not disappear.

It's physics (Newtonian) has it's 'Damping set to 0.19 .

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  • $\begingroup$ nice idea!!! ;) $\endgroup$
    – Chris
    Commented Mar 23, 2022 at 10:31
  • $\begingroup$ Took me a couple of days to come up with that. $\endgroup$
    – Edgel3D
    Commented Mar 23, 2022 at 10:45
  • $\begingroup$ Unfortunately, my "in project" example uses a lot of different collision objects, each with different animations; so it'd be a lotta work to set this up. (20+ collision objects) I ultimately went with increasing the amount of subframes as suggested by @Blunder which made it overall less noticeable in my project and passable in my eyes. I still find this to be a pretty clever workaround, though, and have accepted it as the answer. $\endgroup$
    – spyro
    Commented Mar 26, 2022 at 22:13

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