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Found 628 results

  1. Hi. I am crawling from being a Houdini beginner to intermediate and with flip sims I had a few ques: 1. Both geometry and volumes can be used to construct flip simulations. I'm not quite sure when one might chose one over the other and specifically when you might feed a volume into the flip solver. (is the post solve input, the input for the volume?) 2. When building a flip sim i'm a bit confused when you would use the flip source node. You can just use the geometry as the sop path for a flip object in the dop network. So why/when would you use the flip source node? Thanks
  2. Hi, I'm having some trouble getting the 'Vorticity' attribute to show up in my cached sim: I've already made sure to check the 'Keep Attributes' for the fluidcompress node with 'vorticity' previously also checked 'Transfer Attributes' with 'vorticity' Also tried recaching everything again, but it still doesn't show up. Will appreciate any help I can get, thanks!
  3. remesh fluid sim

    hey! I'm looking into remeshing a flip mesh to constraint it to a particular topology, so basically I want to project a given grid vertically into a flip mesh surface. I think I can do it via the ray sop but I can't seems to find the right way
  4. I am creating a long animation of a boat on an ocean surface. I am using the new guided ocean surface with Houdini 16 to make use of the extended fluid surface blending to an infinite ocean. I am encountering a couple of problems, one being that as the sim continues the boat becomes a submarine due to so much fluid, but also, relating to the topic of this post, white water emission is occurring everywhere making blending into the ocean a problem. The question is, how to I use the volume mask created by the particle fluid mask node to reduce the velocity, curvature, and vorticity of the compressed fluid sim so that the white water emission will blend better with the infinite ocean? Any insight would be very welcome. Thanks
  5. 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!
  6. 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
  7. 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
  8. Distributed Simulation with Deadline

    Hey all, I have a large scale FLIP sim which I wish to distribute into slices and submit to a render farm using deadline. Following documentation from thinkbox and sidefx I have set-up a sliced sim ready for render however when submitting to deadline only 4 files are submitted (1 for each slice) and fail usually fail to complete with no file being outputted. The Documentation from thinkbox reads as follows: "The Houdini submitter allows you to submit a job that will run a distributed simulation. In order to submit a simulation job you will have to first set up your fluid simulation. Once you have your simulation set up, click the Distribute tool found on the Wire, Cloth, or Particle fluids tab, select the item you wish to distribute and then press enter. This will create 3 new nodes, the specific node that controls the simulation will be sent to Deadline as the new distributedsim node in the /out tree. This node defines how many slices your simulation will have. Once you have the distributed sim node set up, submit it to Deadline using the regular Deadline in-app submitter. Additional information for setting up distributed submissions and the properties defined in the nodes can be found in the Houdini Documentation." Implying that there is no additional setup needed. Any help would be greatly appreciated. Thanks, Stafford
  9. 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
  10. source flip fluid with velocity

    hey! I'm trying to emit a flip fluid with some velocity, I can add a generic velocity in world space but in my case I want to add velocity along the normal of the object sourcing...just can't figured it out yet
  11. Hello Everyone I am mixing fluid colors in a pretty simple small scale flip simulation. To that point things behave as expected. This is the problem that I encounter: I set the desired color to my emitter (let's say it is required to match an existing product), the Cd attribute is then transferred between neighboring particles throughout the solve. Ok there. The problem is that, as the colored fluid dilutes inside the clear liquid, the colored fluid then darkens unacceptably and the two never really blend into each other (I believe in real world, the darker color would remain the same or lighten as it dilutes into a clear liquid, depending on the viscosity). This is partly due to the 'at distance' control of the 'transparency color' but in my case I can only set it correctly to either the stream (thin) or to the contained fluid (deep) but not both. Also I am not yet capable to build shaders among other advanced techniques. I would need the color to match a rose pink troughout the simulation. Is anyone able to manipulate some attributes upstream or knows how to render this correctly. Many thanks V Here is a simplified Hip sim easier to move around https://www.dropbox.com/sh/26nzu9mve1ztcmb/AAD3mw4w1hX9O1sXpgeGaDLZa?dl=0
  12. 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!
  13. 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.
  14. FLIP smorganic/sheeter effect?

    Hi, Is there a way to achieve this effect in H? https://vimeo.com/12992186 http://www.fusioncis.com/pr_smorganic.html
  15. 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...
  16. 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?
  17. FLIP Simulation

    Could somebody have any idea how to make this kind of sim? fn.mp4
  18. 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?
  19. 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
  20. Playing with vellum and FLIP, trying to create floating vellum objects. a. Using a simple Merge node with Mutual Collide Relationship, works for the Rigid Body solver but not for the Vellum solver. b. The vellum object doesn't collide at all with FLIP but when turning the Merge node to LeftAffectsRights, collision works but as expected no feedback force from FLIP. Any ideas? Thank you.
  21. 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
  22. 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
  23. 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
  24. 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.
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