So I managed to solve how to get a particle to rotate around it's trajectory using VOPs but there just gotta be a simpler way to do this kinda stuff than messing about with math in VOPs, right?

And don't get me wrong, I love the level of control you have doing these type of setups in VOPs but sometimes you just want a simple solution.

Actually if you don't have the orient attribute on there, the copy sop will align to v. In your case you could set the copy sop's rotate to 90 on the x and then $FF on the z and it does almost the same thing. You could use a simple expression using $PT to randomize that.

The other easyish way, would be pop spin. This will spin your particles, but you will have to put in an expression similar to what you've already set up in your pop vop to get it to align the axis to v, and to randomize it if wanted.

The cool thing is, now that you have that work done, you can save that as an otl (hda), or as a preset for the node. You only have to create it once, and then you can easily reuse it and modify it for future use. Actually, look inside of pop spin and you'll see it's actually just a pop vop as well. You'll probalby also want to look at torque. Pop spin should explicitly set angular velocity, whereas torque acts as a force on the spin.

That being said, I agree that it would be nice if some of that stuff was easier (rotations suck). You can always do feature requests too. Something like, "Please include a ‘use <attribute> for orientation’ and had pop spin rotate around v or some other arbitrary attribute. Luckily though, you can add that to the pop spin yourself and save a new improved version of the hda.

Creating the rotation outside the POP is of course really simple - though I prefer doing it in a transform on the copy object side rather than inside the copy SOP so you can still use the point attributes - but in this case the idea was to use the rotation to drive velocity of replicated particles, so it had to be done inside the particle setup…

And this is the setup I was trying to replicate.

http://vimeo.com/124908765 [vimeo.com]

Then I thought, perhaps POPs wasn't the best approach for this and I created this setup in SOPs instead, giving me 100% control over the whole effect, everything from start and end position, in- and outbound directionality, when they split, how many children, their rotation speed around the parent trajectory, noise controls for the trajectories etc… It was just a way more practical approach for creating a fully “directable” effect. I'll post an OTL when I cleaned it up some.

[i.imgur.com]