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Houdini Switching between two static Objects - Fluid Sim

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Hi there Everyone.

So I have a bit of an Issue and was wondering if someone could Assist me.

Explanation of the SIM :
Fluids hit the center using a Magnet force, Gravity turns on and magnet force off causing the fluids to drop into a Sphere where the fluid will be stirred around by moving the sphere.

Explanation of my SOP & DOP Set up :
I have a fluid objects (Spheres) that I use a Copy to Points SOP and mountain SOP to displace from the center and a few transforms to get a decent scale.
I then Created an Object in the middle for them to Collide with.
Check the first image attached for the scene.

I then have Another sphere where I want the Fluids to interact with but the fluids must remain within the Sphere.
I have turned on Invert Sign to do this and have tested it to know it works.
Check second image attached.

I then want to switch between the two objects at a Specific frame so that the Fluid can fall into the bigger sphere and be stirred around.
Check the thirst image for my DOP set up.

I have tried an RBD Keyframe Active, Switch Value and nothing works.
Dose anyone know how I can achieve this affect ?




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Not sure, but have you tried putting a static solver for each static object and then to connect the two static solvers to a switch solver?

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Or just use one collision object and switch them at the SOP level. Just make sure to enable it as a deforming object inside DOPs.

Edited by Atom

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here's how I would do it...by default...you shouldn't even have to 'switch'...why ? coz the sphere collider is already inverted therefore as the fluid hits it from the 'outside' it should go straight thru...and then it should hit it from the inside and be 'contained'....however I saw some artifacts due to VDB padding, I'm not an expert at this so couldn't get rid of the artifacts (there must be a way)

So the easiest way I found was to simply keyframe the damn size of the sphere collider.

(and I didn't use magnet...just a popattract...does the job...)


Edited by Noobini

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Hi there Everyone, Sorry for the late reply, I forgot to turn on my notifications and got caught up in doing the simulation.

Merlino, yes that was one of the first thing I tried, but sadly it did not work.

Atom, I think I tried this, but as the switch happened the Fluid Exploded and wet crazy.

Noobini, I see what you mean. It worked for me but the Fluid had artifacts as well and I am no where near trying to figure that out lol.
I don't know how to use the POP Attract, it didn't work for me, I'm defiantly doing it wrong.

What I did is scale up the Outer Sphere so the Main Sim happens inside then just scale it down when I need to.
A quick question, Could I use the POP Attract instead of the suction (I cannot get it to work like I want it to) to get the sphere to form an object, like the Rubber Toy for instance ?

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no idea about suction...(no idea about FLIP really)...reason I used popattract was I thought you simply want to pull all your droplets towards the centre at the start to collide with the centre collider...so I took the easy way out with popattract...ie. attract particles to a point in space...defined by Goal in popattract

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