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Found 621 results

  1. 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!
  2. 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.
  3. 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...
  4. 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?
  5. FLIP Simulation

    Could somebody have any idea how to make this kind of sim? fn.mp4
  6. 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?
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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.
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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.
  17. 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.
  18. 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!
  19. 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
  20. 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.
  21. FLIP FLUID Mesh penetrates surface

    Hello Everyone, Particles falling into the object. the particles are penetrating. I've literally tried every single suggestion on every forum and I'm still stuck with this problem. Please look into this. Things I've tried: 1. Substeps increase 2. slip-on collision 3. collision guide offset and divisions. Still, this problem exists. Can anyone help https://i.redd.it/3ziqxtmeo2l51.png
  22. Fipping particles 360 degrees

    Hi! I am a bit newbie, sry. I have to flip particles of a grid by 360 degrees, controlled by a null swiping through the grid. Here is my solution so far. Unfortunately I can not solve the 360 degree flip properly. It would be good to have some randomization of flip axis on it too. I wuld like to make some randomization on the scale too. Could you give me some hints on it , or perhaps edit my scene , please? Thanks in advance. Robert Flip particles on grid_10.hip
  23. Hi all, I'm attempting to create a flip simulation where the amount of emitted particles are purged from a pop group (bounding box in a specific location) each frame. I can set percentages to dead no problem but I cant seem to figure out how to do this for a set number of particles. The simulation is a fountain that emits from the top of a centre pole and the pop group I wish to purge from is a bounding box around the base of the pole submerged in the main body of water. I can obviously create this setup with a sink object but the simulation runs over 1000 frames so it becomes very hard to maintain a consistent particle count. I also had the idea of creating a suction force and actually simulating the water being pumped back up rather than emitting but this seems like a lot of extra particles and collision calculations for no good reason. things I have attempted.. Delete by age: doesn't work because I need to delete from a specific location not the whole body of fluid, This means a random number of particles in the pop group are eligible for purge each frame. pop kill: cant seem to find a way of deleting a specific amount in vex(attempted with while loops, @ptnum, @numpt to no avail). pop wrangle: same as above ^^ sink object: deletes all particles in the volume not a specific amount If anyone has any idea how to achieve this please share and thanks in advance! Matt
  24. Independent surface tension

    I am trying to achieve the effect of having a solid piece of geometry sitting as a fluid, being brought in by either volume source of pop source. This initial piece just has fluid ripples. The second part is I have emitters in the same dop network that are there to create a dripping effect. So it looks like this liquid that is holding shape is dripping. The problem is that I cant seem to create independent surface tension for the two separate sources. If I increase the surface tension to what I need then the main piece of geometry gets washed out. I have been looking for a solution to this but nothing comes up for Houdini 18
  25. Instances following curl noise?

    Hey magicians, Anybody got a clue on how to achieve something like this? first thought is some flip with curl and instance geo, but did some tests with no luck. 4WEj4HDysF.mp4 Thanks!
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