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Found 612 results

  1. 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.
  2. 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. disappearing_mesh.mov
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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.
  8. 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.
  9. 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!
  10. 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
  11. 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.
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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!
  17. A small fluid-related question

    Hi, Currently, I'm working on a small sim where a character gradually fills up with water. I'm trying to have more control over the emission rate, when using the emit particle fluid shelf tool. It seems like the "Scale Source Volume" slider on the Volume Source DOP has been removed. Normally, it would be found below the "Activation" slider. I attached a screenshot of the parameter view of said node. So, my question is as follows: where can I find a similar parameter in Houdini 18? Best regards
  18. When you have complex ocean spectra layered together using masks with varying speeds, and even animated timescales, retiming them while keeping the same approved look becomes a technical challenge. In this lesson you will see how to achieve this as a procedural post-retime operation, without having to modify any ocean spectra individually.
  19. FLIP volume loss: water wheel

    Hi folks, first post here. I've been doing some tests with moving FLIP containers, and for the life of me I can't seem to fix this issue with particles disappearing into the collision mesh. This example uses 10 substeps on the DOP network just to rule that out as an issue (though it doesn't seem to matter whether substeps are there or on the solver itself), and the collision mesh is run through a collision source node, which does generate reasonable looking collision velocities (viewed using the FLIP source guide). I've tried reseeding and turning on particle separation with similar results. Scene file attached - would really appreciate some tips, thank you! Water Wheel v_01.hiplc
  20. Choice between Ripple Solver or full Flip Sim

    Hello, I need to produce fluid animation to get close to this reference picture: The left side should be a very soft wave hitting and bouncing on the bottle, the right side should be a bit more agitated water but still very smooth in general. My dilemma is that i'm hesitating between "faking it" and using a mix of ripple solver and other "non-sim" ways to deform a mesh, or to go for full on flip sim. From what i tried already, and what i read, having very calm/subtle flip sim is not easy to achieve at all, so i was thinking for now that the first "faking" solution would be more appropriate. I would be very interested to know how you would approach this situation. As an example, this is what i'm getting for now for the left side with a simple ripple solver and some caustics. The caustics helps a lot to make the render interesting but the movement of the ripple is a bit boring for now.
  21. UV on FLIP using Rest

    I know this question has been asked on here a few times but I still cannot seem to get a straight answer. I watched the 16.5 FLIP masterclass on how to use the dual rest solver but the thing is Jeff Wagner never actually got it working. If you open his scene files and disable/enable the VOP node you can see he actually didn't do anything- it's the same UV result either way coming from the UV Quickshade. Then I tried to read up on the Dual Rest and Dual Rest Solver nodes, to which there is essentially no explanation in the Houdini help. And while I understand the concept of the Rest SOP measuring the distance between initial positions and deformed positions on points, I still don't understand how to translate that into UV space. So I want to just put this to bed by asking a straightforward question and hopefully receiving a straight answer! (Please no links to other threads I literally have been down a rabbit hole on this several times with no good answers). I want to take the rubber toy test geometry, add it to flip with simple fluid source and FLIP object, use gravity to smash it against a floor plane. Outputting dual rest attributes from the flip solver. In this scenario, how can I- a - take the initial UVs from the geometry and have them deform with the sim b - take the dual rest attribs and use those to UV on my own with a procedural texture
  22. [SOLVED] @P in Flip/POP Vexpression

    Hello everyone, I am currently working on something with FLIP Fluids and need to decrease the POP Windforce depending on the distance to a point. I assumed I could use the Vexpression inside the POP Wind but I can't seem to be able to access the particle Position. I have created a basic HIP file. Inside the AutoDOP Network, you will find the POP Wind in which I'm simply trying to export a test attribute that should be "@P". I've already tried a couple of things like Google, reading the float values separately ("@P.x"), or simply using it like I would use VEX in SOPS ("float length = length(@P);"). I am sure there is an easy way that I haven't found yet or a logical reason why I can't access "@P". Any help would be appreciated! Position_in_Vexpression.hiplc
  23. Was experimenting with the fluid sims and I had an idea to make the fluid affect the object as if it was a paint for e.g. if we threw a red paint bucket on the wall it will leave stains behind.
  24. 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
  25. Hi all, new to the forums and new to Houdini although I have a long history in Maya, I have never really gotten much into simulation until now. I've been messing around with the shelf beach tank to make a simulation of waves for a project I'm working on, but I'm a bit stuck on the caching phase. Currently I have a file cache for my fluidcompress and then one for after my particlefluidsurface that then goes to render. Everything seemed to be okay, but I wasn't really able to scrub the timeline without long cook times seeming to come from the Import DOP I/O node. Rendering with Renderman also would get stuck on generating scene. I saw that you can save to disk right in the DOP I/O, but I'm going with a final particle separation of about 0.07, ending up in 6 hour cache times and 100+ GB for 150 frames. I'm guessing this is normal? My machine is 32 GB RAM with a Ryzen 7 2700X CPU. Just don't want to waste time and space on something that was not the best solution. I am left wondering if instead of the DOP I/O node I should be using a filecache after the delete_boundary_layer node, since that node seems to get rid of a lot of unneeded particles? Or maybe I am supposed to be caching in the beachtank_initial geo after the wavetank? Before the OUT null? I was under the impression that once I've cached the compression node that Houdini would have all the information it needs to render the surface that comes after and wouldn't need to "cook OP" the import_fields from the DOP I/O. TL;DR Just caching compressed and particlefluidsurface I'm getting long cook times when going to new frames, so where else should I be caching before that to speed things up? I've attached a screen of my node tree to show what I mean. Thanks in advance, really trying to wrap my head around the best practices and make sure I am not missing a step somewhere.
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