Birth Groups And Force Assignments

[steven]

Hey there,

I'm wondering if anyone knows of a thread, help card, or quick insight to Birth Groups and Fields. I've got a location POP birthing particles every 100th frame and a force pushing them (simple bursts). I want to put particles into unique birth groups and apply random force values. How do I create unique birth groups? The Birth Group field doesn't accept "group_$F", and I'm not sure how to define a creation rule in a Group POP without creating a group for every frame.

Any help? Seems simple but the group fields don't work the way I thought they would.

Thanks heaps!

[steven]

Okay, dug more into the docs, fishing.

I'm birthing every 100th frame in my Location POP. The Birth Group is gr_burst and I don't preserve it.

Appended a group POP. My Source Group is gr_burst. The Group Name is burst and I do preserve this one.

The grouping is set to Rand for sorting into groups.

# of Groups is $NFRAMES/100 ( to allow expansion based on timeline)

Group Index: floor($F/100) -1

This gives me groups named:

gr_burst

burst1

burst2

etc.

So far, things seems to work. My Drag POP looks at burst* for its Source Group. What would be a good approach to randomizing the Scale parameter based on group index here? One scale for the lifetime of the particles in that group?