POP H13 Self Collision

[Diego A Grimaldi]

Hey everyone,

 

I know this question has been asked before but I don't think the answers have been really satisfying.

 

So here it is again:

 

I'm trying to create a self collision effect like the way that nParticles do so easily (see link below)

 

http://youtu.be/gfkDZQD-Hbo

 

I'd like to be able to do it without RBD or FLIP, just by using the new POPdop, because I know how to do it in the old pop but it's quite slow and I like the new POP system much better.

 

It'd be great to be able to consider the radius Per Particles so copy stamping could be simplified. I think it could be even used to make snow/sand sim.

 

Would it involve writing some codes in a wrangle POP?

 

Thanks everyone for helping

[pbarua]

You can try popproximity which create nearestdist attribute that can be used to trigger popinteract.

[Diego A Grimaldi]

I tried it before without any decent results. If it works for you I'd love to see a hip.

[Diego A Grimaldi]

Anyone, please??

[bandini]

Sorry, but the only way I know how to do this with real collisions is to use a sopsolver/bullet combination. You can use sphere collisions in bullet to help speed up the collisions. Sopsolver creates points/packed prims... You can instance whatever you want after the fact. Because you are using packed prims all the particle dops should work. I show how to do the setup at the end of this tutorial (sorry for the paid tutorial plug).. http://helloluxx.com/product/learn-houdini-jumpstart-vol-4-intro-particles/

 

May work for you, may not... I am not sure how to do this with particles only.

[Diego A Grimaldi]

Hey Adam,

 

Thanks for chiming in. Yea I'm very familiar with how to do it in Bullet (and I've done it that way before), and it's just for my own curiosity, not for a project.

 

I'm just stunned of how easily you can do that in Maya and it doesn't seem so straight forward in Houdini (this comment is gonna hopefully get more people's attention )

 

But if anyone knows of a good way to do it using particles I'd love to hear/see it.

 

P.S. I'm a fan of your work Adam

[bandini]

Thanks, Diego.  Yeah, I am sorry I don't have a better answer for you. I think it is just one of the shortcomings of the particle solver in Houdini, which is meant just to move points around without all of the overhead of inter-particle collisions. I agree, it would be nice to see a nparticles-like solver or node added to POPS to do this. Maybe submit a RFE to support? Rolling out your own POPS solution may work, but I doubt it will be very efficient for anything more than a small amount of particles. I haven't checked, but you may be able to get some possible idea by examining the old SPH solver.

[pbarua]

I'm not understanding why are you strictly after particle. You can easily achieve this using rbd packed object. Since these are single points in space (like particles) so you can use any pop force or other popdop operators. To get fake particle visually look, use sphere with lower radius to emit.  

[pbarua]

Have a look in this example file:

http://www.sidefx.com/docs/houdini13.0/examples/nodes/dop/rbdpackedobject/EmittingObjects

 

You will get idea how to emit constantly.

[pbarua]

Trust me rbd packed object is just like particle if you use sphere.

If you use rbdpointobject shelf tool it will ask you to make that rbdpackedobject or standard rdbpackedobject. If you choose rbdpackedobject option it will copy object at sop level.

Please try these steps. You will definitely get nParticles like feel.  

[pbarua]

And flip fluid is always there which is way faster than nParticles and you get snow, sand or liquid like feel using microsolvers.

[pbarua]

Check these threads:

http://forums.odforce.net/topic/20943-multiple-rbd-packed-object-emitters/

http://forums.odforce.net/topic/20915-emit-rbd-problem/

[Diego A Grimaldi]

Hey Pradeep, yea I repeat I'm very familiar of all the other methods to achieve the result that aren't particles in Houdini, I just wanted to know if there was a way to simply do it in POPs, that's all.

 

Thanks anyway

[pbarua]

Here is a video by Matthew Puchala.

https://vimeo.com/111449179

 

May be he can help you more.

[Kazaloo]

Hey guys,

while I was looking around for a solution I found this thread. I know it's old, but maybe other people find it as well..

I found a solution to stick with POPs - I ended up using the POP Grains node. Just make sure your particles have a @pscale attribute (ie. by using a POP Wrangle after the POP Source). Use the same @pscale as the seperation in the POP Grains and it should work. It's also pretty fast. To visualize it it helps to use a POP Sprite.

Cheers,

Chris