I'm having a problem where for some reason i can't kill my particles. To be honest, i have no idea why this is occuring.

Example: I simply am trying to delete particles that fall out of a given area, so $TY < -2 …

I tried many things but none actually seemed to “kill” the particles. First, I tried a group pop, with the rule set to $TY < -2… It seemed as though those points were being picked up by the group. I then layed down a kill pop, and set it to kill all particles and to the kill group… I still saw the particles being simulated though… So I tried setting their state to $DEAD == 1 in a state pop. This didn't seem to do anything. And lastly, i'm aware I can just delete the points in sops, but, won't there still be uneeded calculations of those particles flying off into nowhere land in the pops sim? Anyways, if I try to lay down a delete node and set it to the “kill_gr” it doesn't kill the particles either, so it makes me think it's not even picking up the right particles. And so lastly, I just created a delete sop, and set the expression in there to $TY < -2 and it kills the particles :p

Please if someone could help explain to me what seems to be going on, i'd really appreciate the time and effort.

Cheers,
Jonathan

Hi Jonathon,

My first guess would be the ‘Enable’ Flag of the Group POP. This is turned off by fault.

Or you could simply say in your Kill POP. “$TY < -2” should work.

If you still can't get it. Maybe try posting a hip file showing your workflow?

cheers,
-j


ps.
Because it's POPs, it won't actually delete the points till AFTER they go below -2. So for one frame, they will exist below that level.

Thanks for your comment jacob, however I did try all of the suggestions.

Here is my hip

Thanks,
Jonathan

Your Group and Kill pop are not receiving the proper group information, probably due to the Split Pop. If you set a * in the Source Group field of either the Group Pop or the Kill1 Pop it should work properly.

wow that was it… the group field just needed a *

it seems a bit strange though. usually when you leave the group field blank, the effect is applied to everything right? am i misunderstanding this somehow?

example:
in SOPs, put a selection of points into a group, then turn the group into primitive group, and then apply a polyextrude node… the polyextrude *with group field blank* is applied to all of the geometry… HOWEVER, if I fill in the group field with the “primitive group” it only works on that group (as expected)…

however, in the case of the “kill pop”, leaving the group field blank, does not apply the kill to “everything”… only when using the *

same goes for the “group” pop… but seems a bit odd, because for example, earlier in my network, i have a group pop, with the “source group field” left blank, and it seems to group the points as expected *with predifined rule set to 1*… however, at the end of my network, when i use the group pop for the kill_gr and the expression $TY < -2… it doesn't work as expected unless the * is in the source field.

And i'm not very sure, when you mentioned it could be due to the split pop, why/how this would cause this grouping issue… (simply leaving the source field blank just seems like it should apply the expression to all points in the network)

I'd love some clarification on this one

reguardless, thanks a lot!
Jonathan

I haven't looked at the file in question, but you'll probably want to look at the collect POP and/or the following thread:
http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=6162 [sidefx.com]