Op like the Force SOP that works on curves?

[rebo]

Hi i want to make a tornado type particle system that is controled by a curve, basically the particles should be attracted to the curve in the same was as you can with a meta ball (i.e. by balancing axial radial vortex and spiral forces) unfortunately i cannt seem to acheive this affect, as the force SOP only works on metaballs.

Ive tried copy SOPing a metaball to the curce, and hoping that that force field would work, but it doesnt I think mainly this has to do with the fact that the directional axis on the force SOP doesnt follow the curve.

Using a curve would be a real nice way of animating and controling my tornado.

If anyone has any ideas how i can achieve this in hourdini id appreciate it.

[stevenong]

Hey rebo,

If you append a Point SOP to the curve, you can assign "forces" to each point under the Force Tab. To take it further, you can multiply the force values with the point number of the curve, assuming 0 to n from bottom to top.

Also, have you tried the Orbit POP? Birth a particle for each point of the curve and use them as the centre points.

Have fun!

Cheers!

steven

[rebo]

The point SOP works great im going to give the orbit POP a go now too.

Thanks much appreciated.

[rebo]

The orbit pop sort of works, however i need two extra things.

1. A way to zero out the Y acceleration from the oribit POP. I was hoping to do this using an attribute pop to query the acceleration at one point in the network, then replace the Y acceleration from the orbit POP using an acceleration POP.

I cant see to get this to work tho by setting the variable in attribute POP params to $AY.

2. A way to make a particle choose its obits POP center by whichever center it is currently closest to. Ive no idea how to do this one .