Hi all,

I’m trying to accomplish results similar to those shown in this video, but I’m having a hard time.
[video]Abstract dance art - YouTube

The two things I can’t figure out is:
1.) how to get decreasing scale as particles move further from the skeleton
2.) how to achieve the rotation as particles are emitted

Here’s what I have so far:
[url]http://i.imgur.com/aPNQv1X.jpg[/url]

I have tx, ty, and tz of the skeleton in both SOP and CHOP form before and after the particle generation. I used a cycle CHOP to repeat the skeleton channels tx, ty, and tz to exactly match the number of samples in the CHOP that represents the particle field. That means my skeleton is repeated for every set of particles, right?

Thinking about it in this way, I should be able to calculate the distance between the skeleton and each particle using the 3d distance formula through a series of math CHOPs. Using the distance between the skeleton and each particle as a scale factor, that would at least give me an increasing scale as particles move away from the skeleton, but as you can see in the link above, that is not the case.

Any help would be greatly appreciated.
particle dance.toe (11.9 KB)

If you really need it based on distance you can probably calculate it in a way like you describe, but I think there is an easier way to do the scaling. Since particles are moving away from source geo over their lifespans, I suggest you control instance s[xyz] as a function of particle age:

You can access Life Attribute (among others) with SOP to CHOP, then you can use the particle Age as lookup index on a ramp/curve that defines particle scaling over lifespan

I think the rotation you describe is a subtle turbulence force in the particle system. Try playing with turbulence parameters on the forces page

I’m on my old MacBook right now so I can’t open your example yet…

Ah, that sounds much easier. Thanks for your input. I will try scaling with particle age as you describe when I get a chance.