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Found 626 results

  1. Hey there, I've encountered imo strange behaviour with my flip Sim. I got Liquid running down stairs. The Liquid should be a bit viscous so I introduced the attribute on SOP Level. For the collider I used volume collisions and a pretty high-res (.002 voxel soze on a 5m Stair) VDB to which I am pointing in my Static Object. When I simulated the liquid with f.e. 100000 viscosity (I tried values from low to super high) its just behaving like water. As soon as I decrease the resolution of my collider it works as expected, or If I increase the resolution of my Flip Sim while leaving the high-res collider as it is it also works as expected. My Question would be: Is there a dependecy between the resolution of the collider and the fluid? does a low res fluid not work properly with a high-res collider? I thought the more resolution on my collider (not too much to keep it efficient) the better. But it seems like that is causing issues -- in my case the solver ignoring the viscosity and the fluid splashing like water while showing correct viscosity values in the GEO Spreadsheet... Thanks in advance and stay safe!
  2. Hi guys, Does anyone know how to achieve this kind of softbody with FLIP viscosity? (pls check the video, it should start at thr right time) anks Th
  3. Hi everyone! I try to create some cool waves in a FLIP tank with another object movement (a basic cube with a subdivide node) When I launch the simulation, a nice wave appears but the liquid level go down but constantly ! Why? I've already tested with substeps of 2 and 3, it's just a little bit better but it isn't the solution, and the calculation increase too much ! Have you some ideas or tips for me ? Many thanks in advance! 006_Waves_test_01.mp4
  4. FLIP Collision with Alembic.

    Hi all, I've been combing the forums trying to get some fluid to stay in this fairly fast moving alembic animation which I think I've converted to proper polygons. I'm wondering how to make the fluid stick with the alembic container (martini glass) while still maintaining some sort of fluidity. As of right now it ghosts through my collision vdb on a faster move. I've tried fiddling with a number of properties like the resolution of the collider VDB / particle scale / particle separation / seeding / attribute transfers , but I fear I've just checked something I shouldn't have somewhere along the way. Excuse my novice ways and feel free to school me on better workflows. Any advice or solutions much appreciated. Thanks in advance. Flip_test.zip
  5. Hi, guys, It's a very simple scene. A torus emit particle fluid into a box . (fig.0) I cached a compressed flip fluid , and retime(speed=0.6) it , the particle fluid surface node will not return a correct result while the "Union Compressed fluid surface" checked. It seems like the compressed fluid surface is not at the correct location and make a very strange result (fig.3). The retimed particle looks ok ,but the mesh not. fig.1 is particle, it's correct , fig.2 is compressed fluid surface, it seems not at the correct location, fig.3 is surface polygon soup. There is a very strange artifact. Is there a way to retime compressed fluid? Thanks!
  6. Im working on a scene where I have some berries falling into milk. The scene is set at slightly larger than real world scale. When the berries fall they are falling at a relatively fast rate. Because of this the dopnet does not have enough substeps to collide the fluid with the mesh (which is a volume collision) and I get a cratering effect like this. I also have the Re-evaluate SOPS to interpolate geometry box checked on. However It does not seem to do anything. The only thing I can do is increase the substeps in the outer dopnet itself, but because of that interpolation, the velocity is less and I do not get as much splashing. I thought it was a scale issue, so I increased the scale to a 5 metre bowl. It still gives the same issue as pictures below. If anyone has any ideas about this issue please let me know. I've been banging my head on this project for three weeks.
  7. Divergence field in FLIP fluids

    Hi, I'm trying to understand how the divergence field works in Houdini, and how it interacts with FLIP fluid particles. Positive divergence should cause the fluid to expand but there seems to be a difference between having positive values in the divergence field and having positive values of divergence in the particles attribute: -If I have positive values of divergence in the particles attribute, the field copies this values (or does some other math operation) and the fluid expands. -If I have positive values of divergence in the field, the particles don't inherit any divergence and the fluid stays the same. -If I disable the option "Divergence by attribute" and have positive values of divergence in the field, the fluid also stays the same. Another thing I can't understand: If I want to fill a volume of 1m^3 using the gasequalizevolume micro-solver with the paramater "Scale Goal Volume" set to 0 then, according to Houdini's Documentation I have to change the parameter "Add Goal Volume" and set it to 1. I tried this and the FLIP solver simply copied the value 1 to the divergence field which doesn't result in any change on the fluid surface. Could some one shed some light on this behaviour, and what is the correct approach to fill specific volumes knowing the total volume value? EDIT: The divergence field is actually working as intended, I was modfying it in the sourcing input rather than in the velocity volume input...
  8. Hi everyone, I have a persistent problem with flip simulations. I have a guided ocean layer sim with a flip surface and a boat sailing (static object in the simulation DOP). The problem being that the inside of the collision boat is filled with particles every frame because of reseeding. I already have "Kill inside collision" checked in the Ocean source node and I don't want to turn off reseeding. Is there anything that can I do to avoid the reseeding inside the collision vdb? Am I missing something in the workflow?
  9. FLIP Simulation

    Could somebody have any idea how to make this kind of sim? fn.mp4
  10. Whitewater SIM issue

    Hello guys, i have a doubt on my whitewater sim.... whitewater01.mp4 i want whitewater to be only on the areas of splashes not on the previous frames rising up... could someone tell me how to make that work?
  11. Hi there! I'm still new to houdini and I'm having a lot of trouble on a project and was wondering if I could have some help or at least some direction on how I could achieve this effect. The project is to simulate a pool of lipstick with a rotating animated object in the center. To resemble the lipstick viscosity I wanted to make a very dense fluid/particle sim, with some clumps of even denser material. Here's the best reference I could find for the effect https://youtu.be/zBGgfPXwLMQ?t=165 . I tried to make a Flip sim with high viscosity and create a viscosity map with a noise sop for those extra viscous chunks, but I couldn't make clumps like I wanted to. I don't even know if the Flip solver is the best tool for the job, but I couldn't think of anything that would get me closer to what I wanted. I also tried to create a few pieces of RBD objects in the middle of the pool, but it didn't work at all. I just really have no idea if I'm on the right direction. I'll add the hip file aswell as a flipbook of the meshed sim. I am using 18.5 by the way. Any help or direction is appreciated. Thank you! lipsticktest.mp4 LipstickPool.hiplc
  12. Hi, The problem is getting RBD Bullet pieces to floating properly: Icebreaker_fake_Buoyancy_Bullet_SpinningProblem.mp4 IceBreaker_Ship_PopForce_VexMask.mp4 im running into problem simulated flat sheets of ice being buoyant in a volume. I can get them to rise to the surface with PopFloatByVolume and also a fake popForce with vex using the pieces depth to mask the upward force. The problem is getting them to not spin around the packed bullet point per piece, and instead have proper per point of the mesh have force applied as per proper buoyancy would. So they lie flat once they get to the surface of the water volume! Struggling with the PopFloatByVolume spin settings, and PopSpinByVolume doesnt seem to play ball either. Im trying to go down the setPrimIntrinsic route, where i could blend slowly the rotation to be flatter as they get to near the surface, but im not hitting gold yet and would be great to know if theres a better route. any ideas or approaches would be amazingly appreciated. attached the hip file with where im at. IceBreaker_PopFloatVol_CustomVolumeInput_005.hiplc
  13. FLIP - Create a Custom Field

    Hey guys, how can I create a custom field on FLIP? I'm trying to achieve this. I guess I could advect the new field using a gas advect but I just can't add this new filed to the sim. Scene file is attached with a small progress Thx Custom_Field_Advection_0101.hiplc
  14. Hello! I am new to FLIP fluids simulation in Houdini and I found that FLIP fluids behaviuor totally changes depending on particle separation parameter. If I make more particles I am getting different shapes. In this Example I am trying to make a fluid splash in different directions. I am setting initial particle velocities by attribute transfer from geometry. And for example I like a shape of splash when particle separation = 0.05, but I want to get a quality mesh with nice thin shapes and round droplets, and for this I need to simulate more particles. But if I'm changing particle separation to 0.03 I have a different shape, with many small droplets and with totally different splash shape. What is wrong in my workflow? How to make a clean mesh with thin shapes, round droplets, not look like a metaballs mesh. For a reference https://www.pngitem.com/pimgs/m/312-3122129_liquid-splash-png-transparent-png.png test_splash_v01.hipnc
  15. Flat Tank disappearing mesh

    I have a problem with the Flat Tank Meshing, when I reduce the influence scale at some point the mesh of the flat tank disappears and I can only see the Splash mesh. The problem ends when I Increase the influence scale over 2.5 but then it not seems water. The particles in flip simulation are correct and the particle separation value is really low. If anyone knows what can be the problem please HELP ME!!! I attach the flipbook to see that. Thank you very much.
  16. Hello forum! I need some help with a flipsim i can't get working right. I'm getting weird jaggy flip movement when I try to use suction force. I use a deforming object as suction object and a fliptank as source. I've tried to debug since 2 days, but hadn't had success so far. i don't know if it has something to do with the suction volume i feed in the sim, or if it has something to do with the sim parameters. it starts to drive my nuts. maybe one of you flip cracks can point me towards the right direction. would be highly appreciated! https://gyazo.com/bb5f005abfd422659194fa4938dcd93d Thank you very much! 2020_11_21_morph_v17.hiplc
  17. FLIP - Spreading Bloodstain

    Hi, I'm working on a bloostain, that shall diffuse/expand over 450 frames to fill up the whole frame in the end (to be used as a kind of 2d transition effect later on) I was able to do a nifty flip sim, but in the end it wasn't behaving like blood at all. To get more of that blood-like rolling diffusion effect, I tried to introduce some viscosity. But with viscosity on, the stain isn't moving anymore. (The bloodstain should already be there, so no dripping & dropping, only expansion in x and z) Tried different viscosity-values, played around with friction and vel as well, still no luck. I think some viscosity could help here, so can someone point the right direction to get it to work? I`ll attach my tries thanks in advance Houdini-Bloodstain.zip
  18. Hi everyone, I have a simple sample scene here, having problem with the flip collisions. - I have a basic deforming sphere geometry that has a colliding liquid which works fine. -Problem part it i also have some liquid pouring on top of that deforming geometry (needs to collide the outer side of the sphere) but seem like there is a square bounding box around the collision (due to negative sdf) geo which gives me unproper collision outside. How can i have correct collisions for both inside and outside of the deforming mesh? thanks. Flip_InvertedCollision_Problem.hiplc
  19. Hello. I'm working on fluid sim which pushes RBD objects. RBD object's interaction(without Fluid) seems fine in Bullet and RBD solver, but when I came to make flipfluid to push RBD objects(not packed) forward, it seems not working. I tried days for fixing the problem, but I cannot find a solution for this... Am I missing something here? Here is the result movie and .hip file(H18.0) of my basic setup. Seasaw_RBD_x_FLIP_interaction.hip Seasaw_RBD_x_FLIP_interaction.mp4 Any helps, kindly suggestions are welcome! Cheers, koba
  20. Flip extruded borders

    Hi, I have a problem with a flip simulation. I'm trying to do a big splash but when I convert the particles to surface, it creates these strange lines or extruded polygons on the border of the box simulation. Someone knows what is happening? I've tried to modify various parameters in the particlefluidsurface node but this only change the place or the shape of this weird polygons. Thank you very much for the help. PD: I can't make bigger the box cause I'm limited by a real camera shot.
  21. Hi! I'm pretty new to houdini's flip fluids and I'm stuck with something. I have a flip fluid liquid simulation with boundary layer for river like effect. I've setup a boundary velocity field to create the river flow. Now that I'm trying to add some pop wind in order to add turbulences, it appears that it overrides the boundary velocity effect. SoI'm looking for a way to blend those two effects. Any ideas ? Thanks.
  22. Hey guys (and gals)! I'm having some issues with my narrowband flip sim as the title would suggest. After meshing I notice that the waterlevel in certain parts seems to be rising and falling over the course of the sim and I was wondering what the reason for this was. I think I've managed to solve this problem before by increasing the thickness of the narrowband but by doing that I have to lower the resolution of my flip sim which I would prefer not to do. Is there a way to solve this issue other than increasing the narrowband thickness? Here is an example, it's most noticeable along the right side of the frame near the bottom of the mountain https://vimeo.com/478367940 Thanks for the read, any suggestion is really appreciated!
  23. RBD and its sleeping properties

    I set up a scene with crates that I want to get destroyed by a flip sim. figured out that I had to put a attribwrangle with i@bullet_sleeping = 1; so that RBD stays in place until the FLIP collides. The problem is now that with a little hit of flip to a group of crate the push activates all of them to break. I am a noob, but found that there is a threshold to control the amount of impact to activate the RBD. I just dont know which one of these it is and how to apply it to wrangler. bullet_angular_sleep_threshold bullet_ignore bullet_linear_sleep_threshold Documentation found here : https://www.sidefx.com/docs/houdini17.5/nodes/dop/rbdpackedobject.html Here is the original failed vid: https://www.dropbox.com/s/dl8ze5rv4vf6gse/Test.mp4?dl=0 Here is current failed test vid: https://www.dropbox.com/s/sa4sumxfqpqmdhq/Flud Test2.mp4?dl=0
  24. How can i achieve this sim with 8 GB RAM?

    hammer flip tank hammer smash flip tank I'm trying this sim with a person walking instead of the hammer guy, but because of my specs, nvdia 940MX, i5 8th gen, it's next to impossible. So I am searching ways to do it with a low res still achieving the ripples and smashes. Also, how can I make only the legs as a deforming body? I imported fbx animation. and selecting the leg geo and clicking the shell deforming body is what I am doing. Therefore only the selected mesh is moving and the rest is staying in the initial place. I just want to achieve this sim by hook or crook. Please don't tell me to up my specs. Obviously, I can't achieve ditto but If you have any idea how I can achieve this with low specs and still not miss out on the core of the sim I would be really glad. and please do tell how to make only certain parts of an fbx animation geo as a collision object.
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