particles created on collision

[JCB]

Hi,

I made a simulation of a collapsing rack using RBDs. Now I want to have some dust or something, that is being created when

they collide with each other. So, what would be a way to realize that?

[SpencerL]

There is a shelf button, called "debris" or something to that extent which would be worth looking at. If you wanted to do it yourself, then you will want to have a look at the dopfield() expression as you will want to extract the "Impact" data from your rbd sim.

This topic has been covered quite a bit between odforce and sidefx forums so im sure if you search around you could probably find an example scene that would point you in the right direction.

[JCB]

yeah, thanks for your answer

I am having some problems with the debris shelf.

I have created my rack by coping boxes, it seems that the debris tool doesn't work with that. I can't see any particles.

If you create e.g. a sphere and break it with the break node it works fine.

Is there any workaround ?

[JCB]

anyone, please !!

[bhaveshpandey]

thats because the debris shelf tool uses a group named inside..

when you break any geometry using the break or the shatter (which again uses iterations of the break tool with a foreach node) it creates broken pieces as well as the surface which is say between them..so when these surfaces start moving away from each other the debris tool initializes the emission of the particles using either edges or surfaces..

I'm afraid you will have to go with the dopoption() or dopfield() expression to get the positions of impact and based on the impulse filter out the unnecessary points which you could then set up as point emitters....or else you could yourself setup the Inside group and use it..

you can get almost any data in the DOPS using the dopfield() expression..

hope this helps

Edited September 10, 2009 by bhaveshpandey

[JCB]

thats because the debris shelf tool uses a group named inside..

when you break any geometry using the break or the shatter (which again uses iterations of the break tool with a foreach node) it creates broken pieces as well as the surface which is say between them..so when these surfaces start moving away from each other the debris tool initializes the emission of the particles using either edges or surfaces..

I'm afraid you will have to go with the dopoption() or dopfield() expression to get the positions of impact and based on the impulse filter out the unnecessary points which you could then set up as point emitters....or else you could yourself setup the Inside group and use it..

you can get almost any data in the DOPS using the dopfield() expression..

hope this helps

thank you!

I am having some problems realizing this. I just don't know where to start. Create an emitter and put an expression somewhere?

I had a look into the Help and saw how to use these expressions, but I actually don't know what to do. Is there any example file I could have a look at ?

[graham]

I've attached a python operator that I created sometime ago that was designed to deal with extracting impact data from DOP simulations. It allows you to choose which specific objects you want to look at: specific objects colliding against specific object. As well, you can choose which information from the impact record you'd like access to. All the data is added as point attributes. Also there is an impulse threshold that can be used to prune impulses under specific values such as when an object has come to rest. It's a bit old and I haven't looked at it in a while but it should be working still. I think it even has a help card.

You could then use these points as the source for your particle emission.

sop_dopimpacts.otl

Edited September 10, 2009 by graham

[fxrod]

Here's another example file that uses a SOP solver to generate impact data and have it manipulated in SOPs. The .hip file contains comments.

impactExample_lisa.hip

[tjeeds]

Daaaaaaaamn, Graham! This is pretty quick & slick, thank you! Much faster than expressions.

I've attached a python operator that I created sometime ago that was designed to deal with extracting impact data from DOP simulations. It allows you to choose which specific objects you want to look at: specific objects colliding against specific object. As well, you can choose which information from the impact record you'd like access to. All the data is added as point attributes. Also there is an impulse threshold that can be used to prune impulses under specific values such as when an object has come to rest. It's a bit old and I haven't looked at it in a while but it should be working still. I think it even has a help card.

You could then use these points as the source for your particle emission.

[Mclawest]

hi all,

I have the same problem with thw debris shelf tool.. I just want to create some smoke from my fractured object. But I don't see any particles I don't know expressions so much to understand where I need to paste it. And I don't really want to use any party tools, I just to understand how to use Debris tool. May be someone can explain this moment? Please...

rbd.hip

[graham]

The Debris tool is built very specifically to be used with the Shatter node in Houdini. It expects the geometry to have all the interior faces belonging to a group called 'inside'. Since you cut the geometry up yourself it does not have this group and hence the errors in the SOP network.

[Mclawest]

oh, now I see... may be I can use my pieces as particle emmiters?

I want to do something like this.

Edited April 23, 2010 by Mclawest