How to control dynamics?

[Brian Jones]

increase friction in the spheres and ground (but being spheres that will only help some) the best is probably to increase Angular Damping (particularly) and Linear Damping in the Force tab of the dynamics tag

[Pierre Tessier]

Friction was already very high at 500%. I increase both angular and linear damping but to no avail. The spheres keep on rolling all over the place.

[Brian Jones]

yeah didn’t think friction would do much since they are rolling which is why angular damping should work, how high did you get the angular? Otherwise maybe Follow Rotation/Position, even drag… And you can reduce the energy in the first place by reducing Bounce in the broom and spheres.

[Pierre Tessier]

Bounce is set to zero everywhere. I did increase the rotational mass to 3000 and that help. Still, some of the spheres are going backwards, which is certainly not something possible in real world. Also, now that I increased friction and reduced bounce so much, several spheres stay glued to the broom! This is not good.

[Brian Jones]

I’m going to have to see your scene file. You have something going on that is not right in your example clip. Spheres are moving backward after the broom has raised above them – it might be the spheres are piling up and simply rolling off the pile but I’d need to see the actual setup.

As to spheres – they look like marbles or ball bearings on a perfectly smooth surface would in reality with a broom pushing them around, so the dynamics system is doing a good job and you are trying to push the settings around until they don’t act like the spheres they are and you might not be able to do that. It might be possible to get the settings right (I’d have to see the file) but I’d try cubes (or something close), they would move like you want with just friction I think. Or if you have to have spheres try using cubes as the dynamic element but place a sphere inside that as a child

[Pierre Tessier]

What’s the best way to transfer you the file? The file upload system here don’t work very well.

[Brian Jones]

I’ve never had a problem with upload here, you just have to follow the steps and copy the link they give you at the end and paste it back into the post (which should be automatic I agree) or otherwise people use a number of sharing services or a dropbox or google drive link etc.

[Pierre Tessier]

I just found the link! Man, you need to know it’s there! Not very visible.

11125_broomtest.c4d.zip

Thanks

[Brian Jones]

ok, had to change a bunch – really I just set a lot of stuff back to normal values and started fresh-ish. The biggest change I remember is with the bristles – I changed them to Moving Mesh from Automatic (which wouldn’t follow the bend and was a reason things were moving too soon). Oh and made the small particles be dynamic as well rather than colliders – as colliders they just make it a really rough floor which probably doesn’t help. Added colors to be able to visualize better. Changed a bunch of settings, frictions (the help says there is no rolling friction at all in the system so some angular damping is needed). Changed the spheres (large and small) to Density. Lowered segments of the spheres and rotation segments the bristles (but increased the height segments) to make the simulation run a bit faster. I ended up increasing the steps per frame some but still with the current setup ended up with some spheres sticking to the broom but now at least they release on the back stroke. However, it seems to be related to the Bend as when I disable the Bends the spheres don’t stick at all. Perhaps the bristles could be soft bodies and that would fix it (haven’t tested that).

Current setup –11129_broomtest.c4d.zip

[Pierre Tessier]

Thanks Brian. This really helped. There are so many possible settings, one can loose its mind.