Killing the particles that are going to be killed in their lifetime

[ehsan parizi]

Hi,

Is there any way to kill the particles that are going to collide with a surface before the collision happens?

a simple example is that when particles don't stop at collision and move through the collision object, Is there anyway to delete those particles from the beginning? In the attached file, you can see some particles don't stick on the collision surface, if there's a way to collect the ID numbers of all the particles that move through the collision obj during the simulation, then we can kill them in sop level, but I don't know how to make a group of all the particles that pass the collision object and use it at the first frame!

Other than that in my original file, I have some particles that move with a very high speed, and I want to kill those too, IF there's a way to group the particles that collide with a surface in their lifetime from the first frame, then I think I can fix that problem too. But still the main question is how to make that group?!

kill_those_mofos.hipnc

[dennis.albus]

You could use a timeshift node and set it to the last frame of the simulation so you have all the necessary information about collisions that will be happening. The downside is, that this will become really slow as soon as your particle system gets more complicated as it has to be calculated for the whole framerange everytime you change it.

-dennis

edit: Just realized that this isn't exactly what you were aiming for.

Maybe you should try to use SDF collisions. There has been a thread about this somewhere.

Edited September 30, 2011 by dennis.weil

[dennis.albus]

Anyway, here's the file to delete all particles that are going to collide.

-dennis

remove_colliding.hip

[ehsan parizi]

Hi Dennis,

Thanks for your answer, but yeah, that's not what I'm looking for. I'm trying to find a way to make an attribute for those particles who "will collide (or have any other specific info) in their lifetime".

[ehsan parizi]

but it took care of the problem! so ...thanks again. one little note though, I used the same setup as yours, but it didn't work fine until I added a group sop after the time shift, and used that in my haspoint expression.