Server Tick Rate Affects Character Mesh Physics

Hi,

I have a need for a pretty high server tick rate. Physics actors work fine but the Skeletal Mesh and/or animation for characters gets wonky.

I want my characters to be able to kick around the ammo/weapon pickups. That works fine in the editor and on the server when it is running with a normal tick rate.

When I increase the server tick rate, however, the character kicks the pickups with much more force than it should. It seems like the server tick rate isn’t being accounted for somewhere.

Or am I doing something wrong? The character isn’t doing anything fancy. I set the collision to Enabled (Query and Physics) but (obviously) Simulate Physics is off. The pickups are simulating physics. And like I said, it works when the server is running at the usual tick rate.

Thanks!

The associated forum thread I posted can be found here.

Sounds like an engine bug, assuming you’re using the default interactions and not applying forces directly yourself. There definitely shouldn’t be such an obvious discrepancy based on frame rate.

There are lots of settings in the Physics Interaction section of Character Movement properties, you could try playing around with those. Failing that, you can disable the automatic interaction and implement it yourself by applying forces on hit events.

Thanks. I did consider the character movement physics options but they aren’t applicable to the skeletal mesh AFAIK. They apply to the capsule component. Perhaps hit events would do it. AddImpulse works fine with the high tick rate. It just depends on how accurate the hit is because I need the velocity of specific body parts (mostly feet). Thanks again!

I’m wondering if I could just put collision components around the feet and socket them. Then I can just have those toss around the crap. Then I can use the capsule to collide with anything else. Saves processing to boot. But even so, that’s just one case and I’d still like to know everything will work right when the server is running faster than normal.

Ah my bad, didn’t realize you were talking about mesh-level collisions. So you’ve disabled collision between capsule and weapons, and the kicking happens when the skeletal mesh itself collides? In that case I don’t think the engine could be doing anything, it would be down entirely to PhysX processing of kinematic body-dynamic body collision response. I think if you can control it more directly (for example with feet colliders like you mention above) then you’ll probably have less problems than trying to get skeletal mesh interactions to behave the way you want.

I can confirm that this also happens in 4.17.0.

You could be right. Whoever’s bug it is, I hope someone fixes it. It seems like the kind of thing that should be fixable. I’ll give it some time for others to chime in, but I guess I’ll try a work-around for now.

Didn’t work. The colliders inherit the velocities of the feet bones. The pickups go flying just the same.