Quicktip: Fluid Splashes Using FLIP

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[@ericburnett8163]

`opinputpath("../",1)` For anyone else looking to the comments to copy and paste the expression at 4:30

[@3DDesigner_]

You saved my Carrier ...

[@lara60690]

ily

[@therealkevinleee]

holy cow

[@AvisAnimationZ]

Love!

[@russdyson]

I had to look this up too, and it uses backticks for the expression rather than single quote.

[@AlenHR]

very cool, thanks for this.. i did tons of flip sims in houdini.. and most of them were small splashes.. so.. i have a tip or two.. for me, the most important thing, regarding general look of fluid, was understanding of relation between Particle Reseeding and Particle Separation.. my thinking was: iterate in high particle separation, and when you are happy, lower the separation for more resolution.. but everytime my sim blow up.. now, i see it like this: particle separation is for world scale, for example, if you drop 1m3 box, and decrease particle separation enough, it would look/behave like a pool of water.. and if you increase particle separation enough, it would behave like a drop of water.. to get more "resolution", aka, avoid jagged edges and/or fluid separating to droplets, there are couple of things to tweak.. one is Particle Reseeding, to get more particles in the same space (smoother mesh) increase Surface Oversampling.. i sometimes went to over 20 for tiny fluids.. Separation tab gives you control of, well, separation:) I found it useful when i wanted to control how quickly and hard everything separates, also influences shape a lot.. Surface Tension in Volume Motion i use a lot for final tweaking of looks, after i got most of the things dialed in, it gives great boos to natural feel turning fluid to nice blobs and thin films.. it really helps with uniform look of sim (everything turning to strings or droplets at the same time).. those are like my main flip parameters i dial in on almost every flip sim i make.. regarding meshing, jagged edges and mesh flickering (tiny holes closing and opening from frame to frame) were my biggest problems.. smoothing/dilating helped, but i at the cost of detail in most cases.. jagged edges get solved by oversampling in sim itself.. i usually decrease voxel scale to 0.5 and play with droplet scale and influence scale to match my desired look.. and i use filtering lightly.. for flickering, i haven't found a better way, but this works great for me.. i cache all substeps and then mesh all the steps (it prolongs meshing a lot).. then i retime result to regular number of frames.. it gives me butter smooth meshes, but it is kinda annoying.. the main thing is to never get too much of a movement between the frames.. the faster your particles move, the more substeping you need for smooth results.. and there is sourcing.. but we all know the importance:)

[@Entagma]

Hey Alen, thanks so much for the comprehensive tips! Think I'll be busy incorporating them into my workflow. Thanks again for sharing :) Mo

[@mohitsherman3758]

@Alen Mianovic you have raised some valid points here, I already had a detailed question pending on Houdini's forum (www.sidefx.com/forum/topic/73817/?page=1#post-312330) but here If you can reply to me, Is there any correlation between the particle count & particle radius? What should I tweak first grid size or iterations so that I achieve a better collision? How can I make collisions to work with thin geo?

[@gt_kenny]

Really nice, detailed comment Allen! Much appreciated. Not every day you stumble upon a KZbin comment that is this valuable. Fluids can be insanely challenging (multiplied by client's requests) so it is always nice to hear tips from others. Cheers!

[@elliotstronge4839]

With the static object the volume sample method isn't being used because bullet is building it's own collision shape which is why you had to change the hull type. If you remove the sop path setting from the settings at the top it should correctly use the volume sample method. Also worth noting, if you use the volume sample method, is that the division method and uniform divisions settings do nothing, it just uses the volume's settings. Oh and in the flip object, under guides/particles, setting the visualization to particles instead of sprites is a better way of visualizing the fluid.

[@JosefMaxwell]

Wanted to give this a shot, so just leave the SOP path setting blank it'll just use the volume sample method on it's own?

[@elliotstronge4839]

@@JosefMaxwell You can force it by setting collision detection to use volume collisions. Then it'll just use the volume settings and not the bullet settings.

[@mylesdarwin3000]

instablaster.

[@user-co4eo8px2e]

doesnt tjhe geometry just disappear if you set the sop path settings blank?

[@MiRaje8086]

Everything is explained really well on this channel, thanks for the content man!

[@vadimrzhavin3740]

Thank you very much! Your tutorials are the most professional and friendly.

[@nathanieI]

Use a File cache node to sim, use save in background on it. It's faster than simulating it in the viewport.

[@phonix6494]

as what would you save it as a vdb?

[@junechevalier]

@@phonix6494 bgeo.sc

[@phonix6494]

@@junechevalier Okay thanks

[@StaticX73]

omg....best explanation tutorial ever!!!

[@valerianarancio333]

Sir, you're the best.

[@tejareddy5732]

Before cube falling(

[@akmusic1066]

I am facing this problem how can i fix this problem 🙁? tell me

[@uzaykisi1863]

How can i bring back the ice cube, i have only glass and liquid in my renderview?

[@PetyaGrozdeva]

Thanks for the tutorial! You are amazing!

[@vasilhristov9005]

www.sidefx.com/docs/houdini/nodes/dop/buoyancyforce.html yes, it's called buoyancy force, does exactly what you're saying

[@eugeneseleznev]

Thank you!

[@akmusic1066]

My fluid is falldown from bottom of glass before cube falling in glass.? How can i fix this🙁

[@StaticX73]

can you point me in the direction of the shading and lighting? I am following this tutorial to the teeth and it has been the easiest tutorial to follow!!

[@ChosenWan]

did you just delete the old version and re-upload this tut? I thought I've watched this days ago.(or maybe I just did a time travel...?)

[@Entagma]

Yes, reupped. Fixed a small error in the edit. Sadly KZbin (contrary to Vimeo) doesn't allow to just switch out the video file. Cheers, Mo

[@horizor]

render without displacment?

[@jquintero462]

Hello, for some reason the file doesn't download to continue with this tutorial. Also after deleting the points from the wine glass what do you do after words? It seems you cut the video and add different points. Thank you.

[@yujinjeon512]

I can't see any ice in dopnet at 9 minutes and 5 seconds. Ice is visible inside the dopnet. I'm not sure what the problem is.

[@cgfan1084]

Great tutorial with the expression for the Sop Path what is the keys on windows for backtake.

[@erichocean8746]

It's below the ESC key.

What happened netflix dark tv series God particle ?

[@jordanobruno4973]

super thx

[@russdyson]

How can I get the ice cube back. Sure I can Object Merge in another Geo node, but then it is just a static cube. Putting the property back to * rather than only flipsolver1 doesn't bring the cube back for me. It looks kind of weird without the ice cube, where an impact crater appears in the flip sim.

[@henry-yu2ju]

I feel like I keep freezing but i know my rig is pretty good..?

[@nvav970]

Why do we need both a collision object and a collision volume?

[@chillsoft]

One is for preview, other is for actual calculation of collisions (also first one is for RBD part of the sim)

[@JohnDowson100]

Beautiful tutorial! Thanks for sharing! I am quite new to Houdini especialy to Fluids, so I hope this question does not looks too foolish.. but is the FLIP simulation supposed to be as fast as it appears in the video? :0 I have 64GB of RAM and an Intel(R) core(TM) I7 -7700 CPU 3.60GHz and it takes an eternity to simulate 35 frames. Is this as it is supposed to be or I am making some mistakes?

[@JohnDowson100]

@Nikodim FomichThanks, this is a relief for me to read this. I didn't knew phoenix FD existed! I see there is also a plugin for Maya. How is this program compared to Houdini? :)

[@alikasaei3391]

Hello, Sorry when I creat the glass and the liquid via flip object, instead of remaining in the glass, the fluid gets absorbed into the glass and disappear. Can you help me fix the problem?

[@LinaVysnia]

Check if your flip particle separation is the same as in points from volume node

[@gouthamvanga5129]

Whats ur PC specs sir?

[@bhcbhc]

yea... where the ice cube go at last?

[@Mati_Motion]

I did excatly 100% same like your steps but flip particles start to fall down and dissapear in second

[@onkarbhade7277]

awesome..!!! plz put rendering tutorial..

[@uvneetsingh2104]

nice tutorial bro i am just having problem my gravity is affecting the fluid

[@Entagma]

Then dial back your gravity, bro.

[@user-ez8sl6oc5w]

how can i visible the cube?

[@Entagma]

Heyhey, a more detailed tutorial on rendering this is part of our premium course on rendering: entagma.com/category/premium-course/rendering-101/ Cheers, Mo

[@KO28JOJO]

The fluid is passing through the glass in my case. Not sure why.

[@chillsoft]

Check your volume collision guide inside the dop network and make sure it looks the same as the vdb in sop

[@csiri6758]

These two blast nodes just really hurt man... I don't know why. Feels wrong.

[@_whittington]

Imagine having 35GB of ram to spare

[@kirtheinson5410]

Hello, I did the tutorial step by step but the liquid comes out from the sides, what can I do thanks!

[@Entagma]

Hi Kirt, did you download the project file we provided and compare your file against that? That's usually the quickest way of finding out what went wrong. Cheers, Mo

[@junechevalier]

You need to increase the min and max Substeps. It's in your flipsolver parameters

[@jquintero462]

@@Entagma Download? Your file doesn't download.

[@eth3realm]

Ploy fill isn’t closing the hole, pls help

[@LinaVysnia]

You need an even number of divisions for it to fill

[@imaginefxproductions2199]

hey! Can we get a tower destruction tutorial with debris,smoke and explosion from start to finish. A lot of guys might want that. Thank you

[@JosefMaxwell]

That's a pretty big tutorial and would probably be on their Patreon. If you're looking for a tutorial like this, check out Applied Houdini on CGCircuit. Paid tutorials, but 3 segments on rigids, debris/smoke and pyro are super in-depth and based off his work with ILM.

[@TroubleShotVFX]

That expression shit is killing me. Isn't there another way or at least an explanation for why it doesn't work when I enter it manually.

[@moonlime-io]

The `opinputpath("../",0)`? make sure to use ` not '. Backtick ` is on the same key as ~, not ". Apostrophe ' is on the key with ". Also make sure you out the ../ directory navigation in quotes like "../" since it needs to be read as a string.

[@xanonymous3468]

the particles set 0.0005 is a huge number..

[@juanecheyt]

Yes, i thought the same thing.... usually if i go under 0.1, my pc (Ryzen9 with 64gb or ram) almost dies, lol..... No wonder he said the sim lasted what seemed like an eternity.....

[@dj_multiple_one]

@@juanecheyt 0.0015 I think is my Maximum on this scale

[@samcare7753]

@@juanecheyt we all need a threadripper :(

[@chillsoft]

Talking about the particle seperation like this makes me think you don't really understand it that well. The PS is context sensitive meaning how big the fluid emitter/fluid object is as well as the scale of your simulation. If it was any bigger, like ten times, then drop the zero. A particle seperation of 0.00015 says nothing if the scale is not mentioned so it's arbitrary until the context is taken into consideration ;)

[@samcare7753]

@@chillsoft I think we’re all jus talking about this sim. It’s pretty low for an i7 or ryzen

[@TheSiimur]

Please slow down when you do these!