View Full Version : vortex field problem

06 June 2003, 03:39 PM
Hi everyone !

I need to apply a vortex to a particle system in order to make a swirlpool.
My problem is that the vortex field also adds a kind of gravity field that attracts my particles to its center. I tried to set the particles' Conserve attribute to 0 but it doesn't change anything.
Can some one tell me how to make my particles just turn around the vortex field ? And not being attracted to its center ?

thanks !

06 June 2003, 07:54 PM
emm what??

a vortex field should push the particles AWAY from the center and not suck them in..

there must be something really odd going on.. check your connections.



07 July 2003, 12:36 AM
Actually Alexx the particles will be sucked into the centre if your Vortex Field has a high-ish value for the Magnitude (eg 50) and your Particle's Conserve is set to 0.

07 July 2003, 10:36 AM
So all I have to do is not to set a too high value for my vortex field ?
But with particles'conserve to 0 I have to wait for a very long time before I get the result I want because the vortex field becomes very slow (if magnitude < 50 for example)...
My teacher has a gnomon vhs about particles dynamics, and Alex Alvarez used this technique to create a kind of galaxy. I remember he set the particles' conserve to 0 and then the field's magnitude to something very high in order not wait for the galaxy to take shape, but in his scene the particles were not attracted to the center of the vortex... I really don't understand.

07 July 2003, 10:41 AM
the thing that might work best in your case is not a vortex field, but either a volume axis field (which can be set to behave like a vortex).

create such a field, use a cylinder as volume shape for it and scale it to have the particles fit in..

then go to the settings and do:
away from axis = 0
along axis = 0
around axis = 10
directional speed = 0

set the magnitude of the field to 10 and the attenuation to 1

that will do it with the particles having conserve at 0



07 July 2003, 12:05 PM
That's sounds like a good idea alexx !
Thanks for the tip !


12 December 2004, 04:33 PM
I had the same problem. The volume axis field surely does help in getting the desired result (in a way though). But the thing is that help on vortex field says that this field gives particles (or other objects) a perfectly circular motion. In other words if we set the conserve attribute to 0 particles should move in a circle (and no matter how great the magnitude is). But they don't. And that means either of three things:
1. a mistake in official documentation
2. a bug
3. I'm getting something wrong
Can anybody comment on this?

12 December 2004, 01:31 PM
Yes, even with conserve=zero particles tend to spiral into or away from a vortex, depending on their speed when emitted. You can almost get a circular motion if you balance their initial velocity with the field strength. If you want a perfect circle, maybe an expression would give you more control than the vortex field.

12 December 2004, 02:11 PM
i can only double the findings of meald about the vortex field and the manuals..
they are simply wrong.

about the volume axis field i found out, that the perfect circular movment only seems to work when applying a rather high oversampling value for the particles.

i will send a bug report to alias about the documentation

i just checked if that may be only a problem of 6.01, but 5.0 does the same.



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