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Macha

Particle force - selfmade

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for rest positions why not just do what the liquid solvers do and have hav a rest variable updated every X frames in the sop solver?

Edited by ikarus

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for rest positions why not just do what the liquid solvers do and have hav a rest variable updated every X frames in the sop solver?

changed your example file to reflect this <green nodes>

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without attaching the file...x_x

Yes, I did exactly that previously. It was my first idea. But I had so many update problems that I worked around it. The only difference I can discern between your and my attempt is that you used a 3-float and I used a 3-vector. I'll have to test it a little and see if it is stable.

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Instead of using the Channel Editor to make my own ramp curve I thought I will go the other way around and make a curve from my function encoded in the Vex nodes.

I did this by copying the parameters into a spare channel in a null node.

This works except that the sampling is way too low. Is there a way to increase sampling in a a specific channel?

See attached images. A hires version from an external app, and the Houdini low sampled res. If I can upres the samples it should look OK and enable me to predict the force behavior as I set it.

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Make sure your Channel Editor is set to display at the highest quality. After that, make sure you're driving it with $FF, NOT $F.

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Here is today's version. I can simulate 30000 particles with this in a reasonable time.

The rest force is now proportional to the main force so that it is easier to get a stable setup.

I have some ideas about a better and simpler force function that I will try next.

It's not a clean file, so if if anybody is looking at it, sorry for the mess.

After that, make sure you're driving it with $FF, NOT $F.

$FF! That's it!

post-4013-128091519159_thumb.jpg

Owner.4684.hipnc

Edited by Macha

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Hmmm...thinking aloud here...hmmm...

At the moment I calculate the magnitude of the force vector with a function. Perhaps it would be better, more stable, precise, customizable and quicker if I was to use a stress tensor instead.

Has anybody done this before? I'm shaky with tensors to say the least, but maybe...maybe...

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I found a much simpler, faster, stabler and more powerful way to melt and crumble particles. I was thinking a bit statistically and figured out I could just base it on density instead of more complicated forces.

I think if I can spend some time on this I could make some interesting effects. Perhaps I could reseed points into this based on density, or change their size, etc. If needed I could sum up vectors again and find out if particles are on an edge, or estimate density based on distance, create anisotropic advection (made up term but I believe I could justify it) etc etc. All very very interesting!!!

Edited by Macha

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easy density calculation using a pc iterate loop, can base ur forces off of that or w/e

Ah, I see, identical to my previously posted setup. You're cheering me up, great minds think alike!

In fact, if it is just simple radius based density the proximity pop is probably sufficient.

Edited by Macha

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Works a lot better and more stable now, taking advantage of vopsop multithreading pretty nicely. It has a very rudimentary volume preservation ability.

As if by magic it creates these interesting mushroomy vortice fluid motions as well, especially at hires.

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Edited by Macha

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Here is the latest. The particles start crumbling from the surface, tumble along the outer edges and fall down, hopefully preserving a notion of volume on the heap below.

I'll give this a rest for now.

Mawi, Pclaes and Putoparri, thanks for helping me with this.

Vimeo is here:

post-4013-128158258038_thumb.jpg

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lookin pretty good, you should try making a building out of particles and seeing how it behaves.

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