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Scaling Each Packed RBD Piece over time after Acquiring activation

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Hi Guys. I have been learning houdini over the past week so I really am new to this, I don't have a solid background in a programming way of thinking but I do enjoy technical challenges so bare with me.  

I have been working on a scene where over time some I want some pieces of a fractured object to be activated in the dops network by selection of a group (I got this part working)

For the next part of this I want the pieces that are now active to start scaling down until their scale is 0. 

I am currently struggling to get my if statement to run multiple times. It runs only once when the condition is met but I cannot get it to loop for each frame.

If anyone could please help here or point me to another forum post I don't mind.


I have linked the hip file and labeled the node I'm having issues with as "Problem".


Plant Debris scale.hipnc

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Hey James, I would approach it in a different way, check it out:

first of all, packed rigid bodies act like particles so you can use the pop wind instead of the wind force (and all the other pop forces, this give us a lot of forces varieties)
Here's how you can set this up:

To make statement run multiple times it must be inside the dop network (use a popwrangle for this)

Idk how to make the pieces scale up or down using vex (never thought of that) so I would do it using the primitive sop.

To use the primitive sop you will need a sop solver. To use the sop solver with the bullet solver you must connect both using a Multi Solver (I know, it looks complex but it's a very common technique, you will see yourself doing a lot of multisolvers in th future)

Here's how it should looks like:



Inisde the sop solver you can set things like this and use the scale parameter to scale individual pieces based on some other attribute (age in this situation)


(Inside the sop solver you can do stuff you'd do in sop context, affecting the dop net stuff)

It looks like it's working fine now, I hope it can makes some things clear for you


Plant Debris scale_fix_02.hipnc

Edited by ParticleSkull
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@ParticleSkull Thanks a bunch Alvaro! I will look into in more tomorrow morning but I opened the file and it was working perfectly! Exactly the effect I was looking for. Thanks for the detailed response It is extremely helpful. Really excited to learn more about the software and join the community. Thanks again!

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