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Found 485 results

  1. I have a meshed FLIP sim (cached out, .bgeo files read back in) that I want to use as a "solid" object and have a rigid body rest on top of it (the idea is that something solid "ripples" psychedelically and the objects resting on top of it move as the ripples go underneath--but the original object is still a solid, and the objects don't sink into it). I just can't get it to hold up, however--when the RBD object is initially "dropped" onto the fluid mesh, it bounces and settles as expected, and does okay with simple early movement, but eventually the collisions become less and less precise and the RBD object just sort of sinks in. How can I get the mesh to read as just a run-of-the-mill deforming object? I've tried RBD solver, bullet solver (obviously doesn't work with the shape of the mesh), volume and surface collisions, jacking up collider volume resolution to make sure all the little waves are getting captured, and boosting the substeps, but the result has been pretty consistent (except more substeps = super jittery RBD as it's reading all of the little pre-big-movement mesh ripples). On the attached setup (a simpler version of the project giving me trouble) I even ran the meshed surface through a "clean" just in case any of the lingering velocity attributes were throwing it off, but that didn't help either. I'm wondering if the fact that the topology itself changes so much might be the problem, but if so I'm not sure how to fix that. Thanks for any suggestions! flipmeshtest.mp4 meshtest.hiplc
  2. I'm trying to create a custom velocity field for a FLIP tank (so I can "pin" part of it down with 0 velocity, while part of it sims all over the place). I'm following this tutorial: https://www.youtube.com/watch?v=xm404aavXrY --but it's from a version or two ago, and when he brings in the volume he created with the velocity attributes into his DOP network, he uses "source volume" and brings in the fields via SOP to DOP bindings (at about 12' into the video). I've crudely sussed out how to use a Volume VOP in the bit where the volume is created to add noise, but not how I could add the velocity at that level (if in fact that's how it's done). Following this model: https://www.youtube.com/watch?v=8UaDetbvMAs I have had success--grouping the FLIP particles in a SOP Solver and using a wrangle to set a custom velocity--but to my knowledge doing it that way won't produce a falloff--it's a very clear line in the tank between the 0-velocity particles and the non-custom particles. Thanks for any help!
  3. Flip Fluid not filling container

    Hey all, I am relatively inexperienced with Houdini and very new to Flip Fluids and having some issues with my simulation. So I have created a container, which I would like to fill with a fluid. I am trying to make it so that the fluid flows into the container and half way down interacts with some text. For this I have placed a static object around a particle emitter and the text is also a static object. While the fluid does flow the particles emitted disappear and so the container doesnt fill. I tried to mitigate this by using a larger particle emitter source but this hasnt really worked. Any one have any suggestions as to how I can make this container fill. I would also like to slow down the velocity of the flow and increase viscosity if anyone could help that would be great. Cheers Alex 190903_Animated_Logo.hipnc
  4. Flip Sphere Motions

    Hey there, I'm trying to replicate this setup: Liquid Sphere Based on my scene, I have a sphere and the particles are generated from it with iso offset and particles from volume. Within FLIP, I tried to control the velocity with pop forces (POP force, pop attractor and pop axis force) and got somewhat of a swirly motion but the in the reference video, towards the end you can see the fluid is ground around a torus like motion and the shape as well Any pointers on achieving this? HIP file attached included. Thanks! SH02_Water_v02.hip
  5. Flip Fluids deforming collision objects

    So I am quite new to Houdini, I have a fairly simple setup where I am simulating the behavior of a viscous material where viscosity is increasing exponentially with age and multiplier. So by frame 120 particles stop moving. I am emitting in a line in a loop back and forth so slowly the particles start creating a layered wall. However I have encountered 3 very intriguing problems which for the world in me I cannot seam to figure out: 1 - When meshing the particle data the particles that are close get meshed (obviously) and I don't really see the layering that I need to. Tried creating a very highrez model but didn't really work. (Is there a way to use the viscosity or age variable to stop particles from meshing together and keep the layering intact?) Currently using VDB from Poligons then converting it. 2 - Despite a very high Viscosity, the particles move somewhat when new layer of particle is added on top. Is there anything like Pop-State (as in previous releases) where I can freeze the particles with attributes? currently using (if viscosity>100000 {v = 0,0,0) to set velocity to 0 once viscosity is high enough. 3 - If I wanted to use a deformable (cloth/plastic/elastic) object to fill the flip fluid into how can I go about this? I hope some of you brilliant houdini artists have some advice or tips on how to go about solving these problems. Houdini file attached. SimCon1.hip
  6. Pro tips for flip meshing?

    Hey guys, I have a little question regarding flip meshing. I'm trying to do some studies using the Particle Fluid Surface node for my final mesh, but I'm feeling something is a little bit off in my results Dunno if it's just the lack of refraction and shading, but my mesh seems a little blobby. I already tried to play with Voxel Scale, Influence Scale, and Droplet Scale, but in the end, it still a little blobby to me My flip sim is ok, good resolution, billions of particles and stuff. Any pro tips? PS: I've already tried the filtering options, masking, etc My mesh Same sim, but only points
  7. How would one increase FLIP viscosity based on particle age, to get a thickening/coagulating effect? My searching only found one how-to from 2012, which doesn't work in H17+. I understand setting viscosity by attribute, but it appears FLIP particles don't have an age attribute, so I'm not sure how to shoehorn one in there. Thanks!
  8. Hero Object rest force in flip

    Hi everyone, I got a flip sim with a hero object Floating on top of it. Now I want to make sure, the object floats but kinda stays on a specific spot. So I used the rest Attribute and subtracted to Position from it (in the dop net). If the distance is getting bigger the force should increase as well. Unfortunately the force is pulling the object to the Center of the Scene. Maybe any quick solution for that? Added a supe rsimple hip file heroforce.hiplc
  9. Hi, I'm struggling with an issue I have at the moment where I have a boat that floats along an ocean surface which follows a curve. The idea is to have a path and an ocean I can evaluate and have a boat bob to the waves (I've done this part) and have a guided ocean simulation follow along with the boat. I've then taken the normal and the up vector and used trigonometry, one unit length circle and vex to create Y rotational data. Then by diving into the ocean source node and applying this to ocean evaluate and boundaries with out interfioring with the ocean spectrum I end up with a rectangular particle source that rotates with the boat allowing me to have a smaller source of particles (instead of a large square centred on the boat) that highlight the back and side of the water next to the boat. My problem from here is the flip fluid solver only takes the centre and size from the ocean source, held inside gas resize fluid dynamic nodes of the flip solver. This gives my fluid simulation an incorrect result. I'd like to be able to apply the rotational values to the flipsolver using position, object position, motion node or anything else that would work. However upon facing this problem I've realised my knowledge in dops is extremely lacking and I'm confronted with green and purple outputs of nodes that don't like working together. I have a feeling this is possible due gas resize nodes ability to rotate for clustering and other pyro Sims, I just have no idea how. Can post my hip when I'm back from work later today, if you have any questions please ask.
  10. FLIP colliders flickering

    So after a very lengthy FLIP sim I'm finding that my colliders are arbitrarily flickering in and out and disappearing altogether. I had done various tests--this happened a lot with lower res settings but seemed to stabilize at the final sim resolution--until frame 240 (of 250). The problem appears to be in the static object itself creating the collision geo. It's set to use volume collisions, mode is volume sample, division method by size at 0.005 division size. The object is an animated person at scale (about two units = 2 meters tall), this setting was about as large as I could go and not lose details. The .abc itself is imported and unpacked. The same object is used elsewhere to drive a pyro sim and it's working fine there. How can I ensure that my colliders don't just disappear?
  11. FLIP Divergence

    Hey guys, I'm trying to use divergence with flip but things get kinda unstable. I'm using only the point attribute, should I use a volume field as well somehow? Thx FLIP_Divergence_v0100.hip
  12. I have a FLIP tank with some action going on. It's just someone diving, so the part of the tank that requires a lot of computation is small, but it's an underwater camera, so with a small tank you see the edges of the simulation. Is there a way to either focus the simmable area in a tank/make particle separation dramatically smaller in one area, to accommodate a huge tank with not much going on so the render times aren't crippling? I've seen tutorials on using lo-res sims to drive hi-res, but that is sort of the opposite of what I'm looking for. I've also seen some endless ocean tuts, but since what I need is an underwater dive, and the breaking of the surface (and the water still beforehand), I haven't found a way to make that work. Thanks for any help!
  13. Whitewater h17.5 Not to emit bubbles

    Hello, Using Houdini 17.5 to create boat wake with white water. Using the white water solver I where I would like to emit foam and spray over the flip surface. However, I do not want the bubbles as I am under the impression this would reduce simulation time and memory consumption. That said, I couldn't figure out a way to stop the solver from emitting bubbles! Anyone was able to deal with this or any documentation or thread that could help?
  14. Freeze Flip Sim

    Hey Guys, Imagine an object which fills with liquid over time. When the object is full of liquid i want the motion of the Flip Fluid stop oder decrease over time. For example: - Object fills with Flip Fluid from Frame 1 to Frame 96. - Liquid and all motion of it slows down from Frame 96 to Frame 144, at Frame 144 everything is not moving anymore. I tried some pop wrangle inside my DOP but i cant get this working. Any suggestions? Should i do this after the DOP in SOP Level in a Vop/Wrangle or could I achive this inside my DOP? And How? Thanks and Greets, me
  15. Hi! I have what is probably a dumb/obvious question. I have a character diving into a pool. He is modeled to scale (roughly two units high), but to get the details of a human diving I'm having to make the collision separation and particle separation very small. The problem is that this is a huge body of water, and the camera is underwater, so the tank can't be isolated to the area of activity or the "walls" of the liquid show. I don't need detailed animation/simulation outside of the area around the diver, just some turbulence to make things interesting. Is there a way I could focus particle density around the area where I need the detail? Can I nest one sim inside another? (The places I've seen one sim driving another have seemed to focus on up-res-ing, and it doesn't seem to fit what I'm doing here.) Or do I just deal with the fact that a large body of water, even if there is not much happening, requires a ton of sim-time? Thank you for your help!
  16. I'm looking to find a way to make a FLIP fluid sim move particles, which would themselves be used to instance underwater particulate matter or bubbles. All of my Googling turns up ways to make POPs influence FLIPs, but I'm unable to find this, and I'm sure it's depressingly easy. The scene is a pre-animated character diving into water. To get the bubbles as he dives it looks like the best bet will be to emit particles with instanced geo bubbles (correct? No matter how splashy I make the sim, I'm not getting any bubbles happening from the dive itself). Thanks for any help!
  17. Good afternoon guys, I'm trying to create a setup similar to the one below. Where the drops are with dynamics and glued to the surface. Does anyone have any tips on how to start this game?
  18. Hey guys, I'm having some issues with a FLIP collision, seems my VDB collider boundaries are affecting the sim, anyone knows what can be causing this? I'm using static object + static solver with a proxy volume as collider. Thanks!
  19. OceanVortex question

    I'm trying to simulate WaterVoltex with Houdini. This is a tutorial on sidefx that is not ours but a credible site. I do not understand, so I ask here. I have set up like a video but the results are not the same. Heap files and video links, I'll leave time Thank you for your help. The reason for this simulation is to create a water simulation using the ship. I will attach a reference video on this If you have any other approach, welcome any way. I will show my enthusiasm to learn Houdini. Thank you for your interest. Plz.. Related Videos Link (19:21 ~ 25:49) Reference Video (4:21 ~ end) voltextest.zip
  20. FLIP - pprevious attribute - What is it?

    At first I thought it was the previous position of the particle but it looks like its the exact same position. Does anyone can explain this? Thanks
  21. Disable (some) FLIP Particles

    Hey guys, Is there a simple way to disable some particles from the simulation like i'd do with RBD? I have a set of particles inside a group and I need them to be stopped at same position but still interacting with the other particles. Does it makes sense? The group is animated I tried setting v=0 but it doesnt work as expected. I did another trick inside a sop solver to get the position from the previews frame so it stays static but then I cant use the resample. Im just wondering if theres a a simple way like like an attribute the would make them sleep. Cheers, Alvaro
  22. Flip Fracture RBD

    Hey guys, im doing a similar effect to the video in question. Not as violent as this, ive done a lot of flip sims but never something where the flip sim pushes an rbd object. The effect im after is like liquid chocolate pushing out from under chocolate that cracks. Any help would be appreciated D
  23. Hello! I'm trying to make an effect where a logo emerges from a tank with a viscous fluid. I want to have the liquid quickly flow off the logo once it emerged. It has a round surface, similar to the torus I exchanged it for in the hip-file I attached. I'm aware of viscous fluid's stickiness and turned on "slip on collision" and also tried the "gas stick on collision" cheat I found in some older thread, as well as using normals to drive the velocity. however some particles always stay on top of the surface and won't flow off. What would be a smart way to cheat and clear the surface of the fluid? Thanks in advance! J. 190620_Instagram_FlipTankExample.hiplc
  24. Greetings. I am the filthiest of noobs and i found a problem i havent been able to solve. I made a very beautiful flip fluid simulation in which two liquid sources mix together. (lots of tuts out there so it wasnt hard for me to do it)...... Both sources have different color attributes and density attributes and they mix flawlessly..... I was successfuly able to do the simulation YAAY!. The problem comes when our pipeline DEMANDS to render in Maya Arnold........ I export the VDB poligon soup via a Rop alembic output node...... and create an alembic file (it exports, it imports into Maya, no problem) BUT..... when i have it in Maya, I havent found a way to mask the fluids, so an AI mix shader lets me use two AI shaders as the two liquids and lets me mix them as they were in Houdini....... I understand there are "Weight attributes" that come with the alembic and they should be the ones helping me mask the fluids, but i really dont know how to do it...... Im a noob both in Houdini and in Maya. If anyone could help me showing me the workaround , i would deeply appreciate it.
  25. Vellum FLIP interaction

    Hey everyone, do you guys know a way of making flip and vellum cloth interact with each other? So not with Pop fluid but flip.
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