Feature Request: RigidBody interpolation

[angusmf]

Would be nice to have physics interpolation built into NetworkedTransform as well as the existing transform interpolation. I only use 2D at this point, but presumably folks will want 3D as well. :)

[TwoTenPvP]

Need elaboration.
Are you talking about syncing the transform and velocity and simply retain the velocity during the wait for the next update? If so, why?

[angusmf]

Sorry, I don't actually know how to implement this other than my (probably poor) understanding of the HLAPI interpolation. I assume you'd want to only sync velocity, assuming that's possible. If the transform is synced as general thing, can you continue to use the physics system on the client?

[TwoTenPvP]

You can't just sync velocity. Won't work. Delta compression would be possible. But that's a different story. As for if you can use the physics system when syncing transform. Yes, you can. No issues.

Should this be closed?

[angusmf]

My understanding is that in normal updates, if I just move the transform of a rigidbody, this degrades the performance of the physics system. So my understanding from that was that it was the reason that HLAPI NetworkTransform has different interpolation modes depending on what the transform is attached to. I'll close for now and reopen if/when I know what I'm asking for.

[TwoTenPvP]

The one who receives transform updates should not touch the physics nor transform system. They should just blindly set the values.

[angusmf]

When using a rigidbody, you're expected not to set the transform position and rotation values directly. Since the rigidbody doesn't know it's just a client, that wouldn't change if valid...would it? I suppose you could disable the rigidbody and rely on position syncs. Then you'd get some weird looking stuff if the send rate was low, where objects appeared not to be bound by physics.

FWIW, I only use HLAPI transform sync mode on my single character type that "flies" using a mechanic that has no basis on physics on the server either.

[TwoTenPvP]

Yes, if you have a rigid body. You are expected to disable the rigidbody on the receiver. I.E the one not in control. This shouldn't result in weird behavior though as the simulation still happens on the other end and the interpolation in place should deal with that just fine.

[angusmf]

I'll just give you the example that I remember reading somewhere, of a bouncing ball for you to explain it to me.
In the simulation, the ball hits the floor and is repelled. On the client, unless a sync happens just as the ball is at zero velocity (has hit the floor,) the ball will appear to float more than bounce since it will never hit the floor.

[TwoTenPvP]

Correct, at that point, it's more extrapolation than anything tho. Syncing velocity is one strategy to extrapolation. I'll consider it and add it if I have time and once all the critical elements are done.

[angusmf]

Thanks for the clarifications. I will disable RB on client and look for anything visibly odd in my use case before reopening. It actually would be a massive optimization not to have enabled RBs on clients.