Hi, I've got a POP net created using an attractor SOP set to use forces from a point SOP on a path

So I've got a nice stream of particles following my curve

Now what I'd like to do is move the whole particle *source* along the same path but at object level moving the source geometry has no effect - I kinda understand why its not moving the particle source (I think it's because either the POP net takes the position from frame 1 or it just doesn't know the source is moving?)

Doing anything in the POP net just moves the particles and not the source emitter
Moving the SOP moves the emitter but then the particles are outside the area of the attractors and go haywire

Maybe I should have done the whole thing with follow POP?

Any help much appreciated
Thanks MarkC

and while I'm here I'd like to recommend the Pinboard tutorial on Techimage's site by Rangi Sutton (it's a bit of a monster -100 pages of pdf)- I've done most of the SideFX videos and some of the Buzz ones but still Houdini was opaque… that tutorial makes a lot of it make much more sense!

This is a common problem when using POPs. Using the POP viewer to visualize particles is all fine and good except that it doesn't inherit object level Transformations unless you tap the “u” key while in the pop network, select the network POP node an in it's parameters set a transform object, usually the object that contains the pop SOP, if it exists. If not, create it then reference it. Once you do that, all the object references will use the world Transforms and you will find that some things may move in your POP viewer.

To get around this whole issue, don't use the POP viewer at all to visualize your particles. In Houdini 6, it is very easy to not use the Pop Viewer as the POP SOP now can directly contain a pop network. It is a simple matter of dissasociating the SOP viewport pane from the network pane and then work on your POPs while viewing in SOPs inheriting all the Object level transforms.

There are some times when you do want to visualize particles in the POP viewer: want to see templated pop guide geometry, force attractor radius fields, etc.

One thing I always do is put the Pop SOP inside an object that is not parented to anything nor has any Transforms at the Object level.

I hope this clears some things up a bit.

thanks Jeff - that helps, Mark