Jump to content

Search the Community

Showing results for tags 'flip'.



More search options

  • Search By Tags

    Type tags separated by commas.
  • Search By Author

Content Type


Forums

  • General
    • Lounge/General chat
    • Education
    • Jobs
    • Marketplace
  • Houdini
    • General Houdini Questions
    • Effects
    • Modeling
    • Animation & Rigging
    • Lighting & Rendering
    • Compositing
    • Games
    • Tools (HDA's etc.)
  • Coders Corner
    • HDK : Houdini Development Kit
    • Scripting
    • Shaders
  • Art and Challenges
    • Finished Work
    • Work in Progress
    • VFX Challenge
    • Effects Challenge Archive
  • Systems and Other Applications
    • Other 3d Packages
    • Operating Systems
    • Hardware
    • Pipeline
  • od|force
    • Feedback, Suggestions, Bugs

Found 520 results

  1. FLIP substeps for fast moving boat

    Hello dear odforce users. I have a question regarding substepping with fast moving colliders. I have a catamaran speed boat which is driving in a straight line at roughly 60km/h. I added some procedural animation to the boat with the help of the ocean spectrum, that drives the wavetank, and CHOPs. Currently the simulation uses 6/8 Substeps on the FLIP Solver and the Solver has access to the sub-frame collision geometry. The problem I'm running into is that the trail left by the boats keels has visible stepping in position and velocity, which causes tendrils to shoot up in the boats wake. This doesn't look good together with motion blur. Should I increase substeps further to get rid of the stepping by brute force? Work out a whitewater setup to mask this behavior? Or is there anything else you can recommend in this case? I'm thankful for any suggestions. P.S. Unfortunatly I can't provide any scene files
  2. AFAIK the ONLY difference in the 2 attached simulations is that in the 'failed' one I have simply reduced my particle Separation from .05 to .025. In each case the resolution of my collision VDBs is directly tied to this resolution. WTF is happening? What should I try to fix this? I need the increased resolution. Pulling my hair out. Launchv11_025ps.mp4 Launchv8_05ps.mp4
  3. Hello fellow magicians, I'm trying to better understand gasequalizevolume DOP inside FLIP Fluids and so far I haven't found anything usefull outside of the Houdini documentation and example files. So I tried to create a simple example file to test it out. So far, I can't seem to create one of the necessary fields for gasequalizevolume to properly work, the goal field. I used a gasmatchfield DOP and imported a pre-created fog vdb with the name goal, and nothing happened. To debug I setup a multifieldvisualization DOP and set the density field to goal, but it doesn't display anything... If some one could have a look at the file and point what I'm doing wrong... Also, if you any information or tutorials on this subject I'd be very gratefull! Thank you Gas_Equalize_Volume_RnD.hip EDIT: The Gasequalizevolume was wired in the wrong input. It needs to be wired into the volume velocity. Still can't get the gasmatchfield to work though...
  4. Hi there, I'm having lot of headaches! I made an extended ocean flip simulation and, once I convert the particles into a mesh, I would like to bake the surface geometry displacement as texture. I tried to transfer velocities to Cd through VOP and use COPs for bake out the color map, but I wasn't able to do it. Basically I'd like to achieve the same result of Ocean Evaluate node in which I can export texture and choose the Cusp to be in alpha. Do you think is it possible to do that?
  5. Proper scale for FLIP

    So this has been mentioned in a few other threads but need some guidelines. My understanding is that FLIP has issues (unstable, flickering, collision, etc) for "small" scale simulations. By that I assume means anything under roughly a metre in largest dimension. What are some suggested starting points for scaling up your simulation for FLIP if its say, roughly a foot or so in diameter. 3X? 10 X? And what about speed to compensate. If you increase the scale 3X do you also need to speed it up 3x as well? There is also Spatial Scale on Solver and was wondering as a first step if i should try reducing to say .1 before I do anything else?
  6. With fast moving collision geometry and FLIP, what are some things to try to stop fluid from passing thru your geometry? Things I've tried - increasing substeps (using 8 currently) - reducing particle separation (I'm at .01 currently) What else should I try?
  7. Hello there! Newbie here, to odforce but also to fluids in Houdini! I have spent a couple of days learning how to set up fluid sims with shelf tools and manually. However, it is still unclear to me how to use custom velocity for fluids. Unfortunately a lot of tutorials are outdated and don't work for Houdini 17. I've been trying to follow Andreas Glad's tutorial on Paintsplats. He uses the normals of a distorted sphere as velocity for his fluid to get a nice omnidirectional explosion of paint. Is it possible to do that in Houdini 17? (It is most probably, but I have no idea where to integrate that velocity information into my Dop Network.) I hope someone can enlighten me on what to look for!
  8. Computational Fluid Dynamics

    Hey guys, im looking to step up my pyro/fluid understanding and study Computational Fluid Dynamics (CFD) since i already got an engineering background. My question, is CFD preferable to learn for computing simulations in houdini? Or maybe another branch of fluid calculations that i know not of? Thanks.
  9. Hi, I'm trying to replicate the vomit tool being talked about in this GDC talk: I'm getting pretty confused by pretty much every step after simming the fluid. Im hoping someone can help me or point me in the right direction to learn about how I would: Convert the fluid into an SDF Write a script that will have every vertex in a grid sample the SDF Use that value to return a colour value Render out the resulting blob each frame aggregate all those frames into one texture that I can step through in engine If anyone can help me with any information to get through those steps I would be hella thankful!
  10. Flip whitewater boundaries

    Is there an easy way that to size my flip container to ensure that my flip sim and whitewater stay within the boundaries? Thanks Josh
  11. Floating Fountain

    A passion project re-using footage shot a few years ago. The water is split into two sims: the first covering the sphere and the downward stream, the other filling the basin and overflowing around the sides. A total of over 7 million particles make up the fluid sim. Software used: Houdini Redshift Nuke
  12. Hi, I am specialized in Houdini FX, Simulations (flip, pyro, RBD Bullet), VEX and Python scripting also a good experience in lighting and compositing. Currently based in Shenzhen, China. you can checkout my vimeo for my work and contact me on LinkedIn. Available for freelance Houdini FX work (Remote work) and Houdini pipeline development (Remote work) Thanks, Mahesh MS. vimeo: https://vimeo.com/maxcolor/ LinkedIn: https://www.linkedin.com/in/maxcolor/ email: msmahesh@live.com
  13. I (beginner in FLIP Fluid) have a FLIP simulation that gets crazy when I add a collision (static object) I use the test geometry shaderball, used 2 spheres with mountain sop, boolean with front and back of the shaderball. The two deformed spheres are the source. The rest (boolean difference) of the shaderball is the collision. Flipbook Without collision https://streamable.com/qkh2p Flipbook With collision https://streamable.com/922a6 Ii feel it has something to do with possible intersection between particles and collision geo, so I reduced the size of the sphere to leave a gap with the collision geo but the flip sim is still going crazy. Any idea? Issue with FLIP simulation.hiplc
  14. Recent work from Chinese animated feature 哪吒 (NeZha), I was responsible for creating and rendering of the water effects using Houdini flip to build a guided system for water and render in Mantra, final compositing done in Nuke.
  15. viscosity problem

    Please help me. I just started studying Houdini. I don't understand now. It's about viscosity. It is in the red frame of the image below. I created a mesh with flip, but it is not smooth. How can I make this part smooth without bumping it? (I using houdini17.5)
  16. Fluid into FLIPtank + interact

    What I am trying to do is to get a fluid of any kind (pop or flip presumably) to interact with the fluid in a flat fliptank. Seems like it should be easy, but I can't seem to get them to react and mix like fluids (or interact at all actually). More detail: I actually am trying to get a cloud of blood to spread out into a pool under a body that has just fallen in. Perhaps this means I need a different solution than if I was dumping particles into the tank from an emitter outside of it, but I can't even get that to interact, so any advice on this would be most helpful, and I am grateful to anyone who spares even a moment to consider the problem. Much appreciated! PS- I have scoured the internet, including this site, for advice on this, and have come up empty handed.
  17. Floating Fountain WIP

    I've been remaking this old shot I had worked on 3.5 years ago, taking the old footage/files and completely reworking the sim, render and comp. Feedback welcome
  18. Hi! I'm making a chocolate dipped strawberry (strawberry model from 4dm-works.com). There are 2 problems. 1) When the strawberry falls into the chocolate, the FLIP is using both bounding box of the VDB and the VDB for its collision, creating this box around. VDB resolution is at 0.007 and uniform division for collision is at 500. (which I thought are high enough?) so I'm not sure what's up. 2) The 2nd problem is that the chocolate doesn't stick to the strawberry. I have the friction, viscosity, density and stick on collision on, but nothing's been happening. I have a feeling it's something super minor somewhere.. but I can't seem to figure it out. How can I fix this? (Bound_Stick_Question.hipnc) Thank you in advance for taking a look at it! -Y
  19. FLIP SIM - How to stop bubbling

    Hi! Houdini beginner here. I'm learning FLIP sim and having trouble with it "bubbling" at the end. It's a water-filled glass breaking (bubbling_question.mp4). Towards the end, the liquid is constantly moving and is creating this "bubbling" look. I've tried adding a POP Speed Limit after certain frame, or setting POP Velocity to 0 after certain frame, but nothing seems to work. How can I fix this? (I attached the hip file but I'm not sure if it'll work due to missing geos and caches: bubbling_question.hipnc) Thank you! -Y
  20. Flip solver problem

    Hey guys, all right? I'm trying to make a coffee capsule rising from a viscous liquid, but some particles are getting stuck and the liquid isn't getting viscous and I've tried everything and can't change any parameters. Could anyone tell me what I'm doing wrong? Check out my simulation. Preview_01.mp4 coffee03.hip capsula_final.ABC
  21. Custom Velocity with Volume VOP

    Hello there, I'm making a classic Ship Sailing Effects (ocean guided). I'd like to add a custom velocity to the bow of the ship in order for me to have a good turbolence like this: Through a Volume VOP (please see the hip attached) I created the following velocity: The shape I had it's what I want (straight velocity to the front and curved ones along the sides of the ship, so they can push the water for having a classic V shape). However, I'd like to invert the value of it: having higher velocity in the center e gradually less on the side. With my solution I have to much velocity on the side and less on the center of the bow. Basically I need the trails to be red (high) at Z=0 and blue (low) at the Max Z bbox. Furthermore, is my solution right? I blast a part of the bow, scattered it and then use a Volume Rasterize Attributes for creating the velocity. And, lastly, what kind of operation do I need to use in DOP in Volume Source? Somebody says "Add", somebody "Pull". What is the correct way? I hope you can help me. Any suggestion will be really appreciated. Ship_Body.obj Ship_Custom_Velocity.hipnc
  22. Paint splash

    Hi guys, Im really in need of some help here. Im trying to find a way to paint a mesh using flip fluids. The idea was to have an alpha of where the fluids collide with the mesh to then use in compositing to reveal a texture. However ive been lookin everywhere an cant seem to find how to extract this information. Here is an example of its use in substance painter Thanks for your help guys,
  23. If you're flip simulation flickers from using reseeding particles this threads for you. TLDR: I've found a temp solution but want a better one. Inside the flip solver search for a node called "Gas Seed Markers"(Its renamed to "Reseed Particles") Uncheck the "Build Inside Surfels". This will stop the popping but maintain the effect of deleting the unnecessarily dense overlapping particles. Starting this thread for myself to document my thoughts on this but also for anyone else who needs reseeding to keep their simulation in check. So far I have a temporary solution to my issue but I want a better one. My hope is that we can discuss a better means of achieving the desired result of consistent fluid particle density without flicker or popping. The masterclass doesn't explain reseeding and I couldn't find much on the topic in forums or elsewhere for how it works. The node responsible is Gas Seed Markers(GSM form now on). It checks the number of particles per voxel within the surface field for inside the fluid and outside within a given number of boundary voxels and does three things. A. When particles exceed the desired density per voxel GSM will cull the points of that voxel. B. If voxels beneath the surface do not have the correct density GSM will add points. C. If there are not enough particles on the surface, within 2-3 voxels GSM will fill that voxel with the desired number of points per voxel. It seems on one frame the GSM node will delete ALL particles within a voxel that exceeds the limit. Then the next frame, because the void was created it will then repopulate the void with the desired density. So this is where I'm hoping for some help in understanding, in order it's: 1. GSM determines particles are too dense. 2. GSM deletes all particles in voxel. 3. Complete solve (particles partially close in on this void) 4. Next Frame of solver - void still exists so GSM adds particles to this voxel with points = Flicker / Pop. So to start the thread: First - Does Gas Seed Marker delete all particles within a voxel that exceeds the density limit or is this an optical illusion? Second - I'm having trouble getting this node to function outside the context of the flip solver. I want to see it populate points into the Geometry data but it has a lot of requirements regarding the slice index that I don't fully understand. If anyone has or can create a working example of this node functioning outside the context of the flip solver I would greatly appreciate it. For now I'm going to try using two GSM nodes one after the other. The first only performs the cull operation and the second performs the fill before processing the solve. Will post back with results shortly.
  24. create flip tank inside object

    hey there, im newbie to houdini and here. Im trying to achieve fluid in bathtub, easiest way seems like using flip tanks. But i don't know how to do that with custom shape instead of box. Also i will add some rigid bodies top of that water later. Also i tried to fill it with particle emitters but i couldn't success. Also how i freeze it after it fills, initial state ? In short: bathtub with water, floating rubber duck and some other model in surface. attached scene file. bath.hip
  25. Hi, I am summoning all of you flip gods! In the images you can see the flip explodes upwards for no apparent reason, this seems to happen along the boundary of the collision object. I am using guided ocean layer setup. The collisions otherwise behave correctly. I have tried high res sim, low res sim, changing grid resolution, changing collision geometry (submarine model, simple scaled sphere), deforming collision geometry, object transform collision geometry, zeroing out collisiovel field, high resolution collision vdb, low resolution vdb, playing around with depth of the guided ocean layer, different amount of substeps(both flip solver and autodop), reseeding settings, changing integrator types in the flip solver and probably more... Quite frankly I am at my wits end and I wonder if anyone has ever seen this kind of a problem and if there is a solution to it. I would also like to avoid making the boundary layer exceedingly deep, as this would most likely kill all the detail. I have attached a simplified hip file where this problem occurs. Thank you exploding_water_problem_v1.hip
×