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Found 673 results

  1. Any other suggestions on how to take a large wavetank sim, and crop just a small swatch, to do whitewater testing on, instead of the huge tank? I need to take the compressed fluid cache, and crop out a small bit. Tried something like this which sort of worked, but the whitewater source changed completely, so I am guessing I am screwing up something? Cheers! this is the ww source before cropping - this is ww source after, completely different as if it has more curvature?
  2. Flip Simulation Collision Question

    I am trying to create a bubble using white water with simulated data in water. This may be a basic question, but my skills are lacking, so please help. Is it possible to reduce the collision area in flip simulation? I want to reduce the collision area only by the red part shown in the figure. And in case of objects moving quickly in water, there is an interpolation phenomenon when simulating white water. Any tips on how to solve it? thank you.
  3. Guided Ocean vs Wave Tank?

    Ocean experts - what is really the difference these days between a Guided Ocean and just a Wave Tank? Are Guided Oceans just legacy and no use anymore? Pros and Cons? Cheers!
  4. Hi all - basic FLIP question around detecting particles that collide. I have a simple setup (see screenshot) and I need to detect and group particles that collide with the static object in order to assign a new Cd to these collision particles - hopefully determined by either a ramp OR a texture color from the collision geo. I'm having trouble finding good references for detecting colliding particles in a flip tank / flip solver setup. I found several tutorials covering setting up a pop collision detect node for a pop solver, but I'm unsure how to translate that to a flip solver - or even if a pop collision detect would work with a flip solver. Any help or pointers would be much appreciated. Thank you!
  5. pop fluid splash

    Hello, I am studying after watching this video. I want to make a splash with a faster speed than this video. If you increase the gravity value, all particles will receive the gravity value and go down. Is it because the mask value is not applied well? Help. thank you.
  6. Hi all! I have a sim that does both, FLIP and RBD. All works fine so far, but I am struggling with caching it in an efficient way. I am using two separate DOP import streams to fetch the FLIP and the RBD and caching them out. As the sim is too high res to fit in memory that means that after e.g. caching out the FLIP I have to run the whole simulation again to cache out the RBD! There must be a better way... Any input appreciated!
  7. I'm having an issue with the Beach tank shelf tool when I try to use the Ocean Waves SOP (along with a couple of Ocean Spectrum SOPs) to seed the waves. As you can see in the video, the velocity of the waves seems to be transferred to the boundary layer of the simulation, but nowhere else, and the passing of the instanced waves seems to have little impact on the simulation, when the waves should in reality be breaking on the beach. I've already played around a lot with this and I believe it could have something to do with the velocities of the points on which the waves are being instanced, but I'm not sure. Any suggestions would be great, thanks! Beach Tank Issue.mp4
  8. Scale down ocean guided inputs

    Hi, I am trying to simulate an ocean guided flip with a maya scale spectrum (1 maya unit = 10 houdini units). Since I did not find a way to properly scale down the a spectrum , I am down scaling down all the inputs of my sim : _ The particles -> Transform SOP _ The grids (surface, vel, guided_sink, guiding_surface) -> Transform SOP + scale down values _ In the solver I scaled down all the parameters linked to the Ocean source (particles sep, boundaries,...) My issue is despite those adjustements the waves are "breaking" and not matching closely to the spectrum. It looks like they are just affected by the vel field like a standard force and not really guided. Please let me know if you need more informations. Cheers
  9. FLIP slip field control

    Hi, I'm currently working on a scene where the oil spill on an object. I need to control the slip field so I browse through any video that I can find. I found one pretty interesting, it's a flip test made by Tim Woods on Vimeo. in the comment section, he explained using DotProduct in VOP in DOP level to create Curvature Attraction. This is his explaination: Curvature Attraction is based inside the DOP network as a SolverSOP piped into the Particle Velocity of the Flip Solver. At it's basic level it measures the surface using DotProduct against a vector of 0,1,0. You can use this to mask a test that finds closest mesh position weighted by distance. I also made a mix/slerp the cross product of the surface normal (makes a downward flow normal). This helps keep the flip moving, otherwise in some cases it can slow down when you start to add upward vel to it. Can someone help me on this part, I don't know how I should wire the DotProduct also how to create the attraction from it. I would be appreciate if someone could give me a hand in this. Thanks in advance.
  10. Variable Surface Tension

    Can somebody please help me with this surface tension problem. I have a scene and i want a different surface tension to apply to different group as show above. I want the group 1 to have higher surface tension and group 3 to have a lower surface tension but my setup is not working . SurfaceTension.hipnc
  11. Water Splash

    Hi Everyone, I am trying to create a water splash with separate water trails as shown in the below image. I have created separate sim for splash and main water sim. Using object velocity to emit splashes but unable to get proper shapes of water splash as per reference. Any ideas or suggestions will be of great help.
  12. Dear Houdiniers, I am doing a heavy FX shot, mostly FLIP colliding with geometry and whitewater from that FLIP. I need to cache multiple .sim and .bgeo.sc sequences for various different SOP and DOP nets. It WAS..... all working fine, but now caching anything it seems, whether "save to disk" or "save to disk in background", doesn't work properly. In save to disk it seems to hang and when in background randomly decides to finish early and jump to 100%. There seems to be no pattern to the amount of $SF it gets to, at least none I can discern. I have tried down rezing it and allowing caching to disk to no sucess. I hope someone can help. This is a shot that may land me my first job in the industry, fingers crossed! Cheers 5D PS: haven't included .hip because it has so much cache all over the place. Should I upload it anyway??
  13. Hi all, after running a guided ocean sim, I have meshed the particles using particle fluid surface, and the resulting surfaces have a “bottom” layer which I would like to delete. Using connectivity SOP and setting the type to Primitive exposes attribute called class, which gives me integer class. Then I used group expression and gave the group name called “kill”. in the Vexpression, I used @class == 10 10 being the class of primitives that comprise the bottom layer that I am trying to delete. Then I put down a blast, and by putting in the group “kill” that I made in the group expression, I am able to delete the bottom layer. so far so good. Only problem is, the class numbers change depending on the frame. So, while class 10 might be the bottom layer that I am trying to delete on frame 1, at frame 2, the class name has changed to something like 12, and my group expression and blast no longer work. How can I use this method when the class changes every frame? If there is a better method to procedurally delete the bottom layer of mesh throughout the frame range (say, 1 to 168), I would love to learn about it. Thank you
  14. Hi Friends! I'm trying to do a floodwater simulation and whitewater came nearly to 1TB, what is the best method to render this as particles or the VDB?(for production use) I have to send this to the lighting artist, sending 1TB caches is tough to deal with for us, looking for help on optimizing
  15. Large Ocean emerge collision issue

    So I have been trying to emerge a temple from under the ocean. but I keep getting this weird collision when it comes from below the water. Looked everywhere if anyone had the same issue, but couldn't find anything. The model is from kitbash and I believe I clean it up and polyfill it so it is watertight. I tried to use another geometry like a super quad from Houdini and that created realistic collisions. Not like in the picture. It seems like it is using the whole bounding box of the vdb of the temple to move the particles. I have collision detection in the solver as Move outside of collision Ocean_emerge_02.hiplc
  16. Hello all!, I am trying to create two different flip sims, which should collide with each other. Sim A is a flat tank, with a suction force and some vortex force. Sim B is a simple sphere emitting fluid. I want Sim B fluid to collide with Sim A fluid. Problem is if I do these inside one DOP network, Sim B inherits all the forces attached to Sim A, I am trying to prevent that. Maybe I'm overcomplicating this whole thing. Any ideas on how I can get them to collide with each other? Please refer to the attached hip file. Thank you all for your time. TwistForce.hipnc
  17. Hi, I still haven't managed to figure out if there is a "right" way to bring in geo/volumes into a dopnet for a flip sim. I have been doing it using a flip source that converts some geo to a volume and then I used the volume source in the dopnet. But the flip solver also needs a flip object as input into the first input pin - even if you hook up a volume source into the last pin. And there is also a default cube in the sop path in the flip object node. I was just wondering why the solver needs a flip object if i'm using the volume source? Thanks
  18. Houdini.School Velocity Forces

    I am happy to announce that https://www.houdini.school has launched and you can get 15% off now through July 27th, 2021. I'll be joining a host of talented Houdini teachers, like: Debra Isaac Kate Xagoraris Beck Selmes Christopher Rutledge Justin Dykhouse Jeffy Mathew Philip Nicholas Ralabate You can learn more about my Velocity Forces class here: https://bit.ly/houdinivelocityforces Teaser video for my Velocity Forces live class: https://vimeo.com/577928177
  19. Push outside Fluid Surface

    Hello, I made a Fluid simulation and I added a particle fluid surface to it, is giving me very noisy mesh where the fluid is making contact with the glass, I tried using a Boolean, but the liquid is not making contact with the glass. I tried using a Poly Extrude, but is also inflating the other parts of the fluid and is making it look bad. My Plan B is to use a Poly Extrude on the glass to make it thicker and use it for the boolean, but I wanted to know if there is something wrong of what im doing on the Fluid configuration
  20. Hello I have an animated Object and when I apply a hero rdb object then the animation is gone and my object is just falling down into the water... But I want it to float on the surface after it has touched down. How can I achive that? Thanks for advance
  21. Hey guys, Recently I faced the flickering issue on the flip simulation. This flickering problem appear when I simulate with custom collision wall. What I want to be is simulating with animated walls which around flip box without any flickering. Because Flickered particles cause flickering of White water and it looks very weird. Is there anyone who can help me? Thanks, in advance! collision_error_test.hip
  22. Hi, I am trying to create a flip simulation of an animated character, such that the surface of the character looks like a violent ocean. So far, my attempt has been to create a character body with suction fluid, having some emission as well. However, I am not getting the effect I am looking for. The fluid surface created by the suction force is very smooth, but what I want is for there to be ocean waves flowing around in the surface of the character, if that makes sense. Have a look at this video: Basically, I was hoping to get the surface of the character looking like the ocean surface in the video above, instead of a flat plane as the base mesh, it should be the character. Any help is greatly appreciated.
  23. I'm trying to create an animation of a ship rising out of the water and simulate the water on it. But the animation is so fast that sails and thin ropes are not recognized as collisions. Perhaps raising the substep is a good idea, but is there any other way? Ideally, the collision should be as clean as this
  24. Hey I am trying to achive the effect of floating but with an animated alembic object. I have tried the feedback scale in the flip solver but this doesn't help me just nothing happening. So now I am asking here, if someone has an idea how can I make a animated object float in a FLIP Sim, help would be very appreciated. The object is the starship rocket stage from SpaceX if someone here follows spacex - it should land in the ocean near Hawaii - I've done a short animation but now I dont know how to make it float... Thanks in advance Flipbook_animation.mp4
  25. Hi there! I have a FLIP + whitewater simulation I'm putting together and trying to figure out what's causing these popping artifacts in the simulation? They seem to pop up every time I try to start playing with whitewater! Preview attached-- thanks for any guidance! whitewaterJitter.mp4
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