I am banging my head on this one.
I would greatly appreciate it if someone could take a look at my VOPs setup and answer a few questions for me … before I kill myself.

1) dive into the helix geo
2) then into the popnet
3) then into the Vops_Roate_Beam

My question is why does this setup not revolve around the input axis?
As you can see it shifted to the side.
I would think it would initially be shifted and then center itself about the z-axis.

I would like for the helix to be centered around the z axis.
I thought that my VOPs setup would accomplish that, but it doesn't.

My next question is, how can I make the diameter increase as z gets larger.
If you just hookup the velocity comming out of the extract vop into both velocity out AND the acceleration out, it does exactly what I want when it comes this question, not the first, but it doesn't make logical sense to pump the velocity into the accelerations and is a cheat, I will use the cheat if I have to but I thought that the helix would be conical without doing that. So basically I am thinking something is wrong with my concept.

If you just hook the the velocity out of the extract vop and into the velocity and acceleration of the output vop and view it and pretend it was centered around the z axis I would be happy with that. Oh and I can't just translate the source to oneside either!

Thanks,
David

Hi DavidMarcus … the “problem” with the offset is because you're basing your “steering” on velocity and not on position. You're asking the particles to continuously turn to the left (or right) completely independent of where they are. Because their turning rate is constant, they will keep going around in a perfect circle (when viewed along the z-axis) which means that their starting point must be a point ON that circle.

I'm not sure what I'd suggest as the best way to compensate for this other than to shift your source point (which you indicated you don't want to do). You wouldn't have to shift it much though. You could have your source just very slightly away from the origin and then have your helix start very tight and grow bigger quickly until it was the size you wanted.

In terms of modulating the size, I would have been more likely to play with the acceleration relative to position than the velocity relative to velocity, since objects travelling in a perfect circle are always accelerating towards the centre of the circle.

Anyway … maybe (hopefully) this helps a bit

Yes it did help, as it verified my thinking was off on this.
If I rotate the position as well as velocity and stick it into position out and velocity out it seems to behave the way I want it to.

Thanks for you help!

:;D (4 eyes)

Other comments are still welcome on this though.
For example, I have three of these beams and want to rotate them so that
they are out of sync by 120 degrees each. I can't do this outside of the particles system though, it has to be done inside the vop or in pops.

Thanks,
:;D

Can you post your latest .hip for examination? That would help re suggestions as to how to get the three beams working.

Cheers!

I moved in a new direction, instead of having 3 independent beams I am creating 3 beams in one VOP. It has its problems though.
For one, the collision object ignores the beams created by the rotation done by the transform VOPs and secondly, the movement applied to the source is being picked up as if it were outside the popnet. If you unbypass the Animate ALL_ENDPOINTS transform, you will see what I mean. Play all the way to the end then you can see the collided particles sliding back and forth, when they should be at rest. Is there some sort of SPACE change I am missing?

Thanks Again.

Even worse, with the two transform VOPs at the output (inside the Vops_Roate_Beam) the animation of the particles do not follow the animated axis of rotation (without them the single beam does follow).

:d