Puzzled by particles and attachments

Can anyone explain this for me, please?

I know that when I play an animation, my avatar doesn't actually move as far the sim's concerned. But if I target a stream of particles -- a chain, for example -- at an attachment I'm wearing, the particles will follow the attachment as the animation seems to change my position, and thus that of the attachment.

Why is this? Something must be telling the particle emitter that its target is 2 meters to the left of where the sim thinks it is.

Because particles, like animations, are rendered client-side.

The client knows where the attachments are, even when animated (since it has to draw them), so it also knows where to emit/send the particles.

Thanks. I think I understand.. are you saying the .bvh file gets downloaded and played locally and, in effect, tells the viewer what adjustments to make, when drawing me and my attachments, to the information the sim is sending it?

Aye.

The simulation doesn't know anything about what an animation does to the position/rotation of your avatar, so attachments don't move, either. Particles are completely client-side, too. The simulator does not simulate anything about them, other than send the particle parameters to other clients in view range for them to do the rendering.

As such, the client is doing all the work of positioning the avatar, attachments, and handling the emission and movement of particles. Thus, it doesn't need the sim to tell it anything more, and the sim doesn't have to know anything about what the client is doing with them in order for it to work. If you notice, some dance animations will move your avatar out from under your name tag. Your name tag is basically where the sim sees your avatar, and it doesn't move no matter what animation you play.

Thanks. I knew that animations don't actually move people; what was confusing me was how the particle emitter seems to know where the target is when the animation appears to move one or both of them, but now you've explained it so I can understand.