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Found 66 results

  1. Hi all, I am trying to make a whirlpool effect and i am doing it by creating a circle and then copying it into itself creating a for each loop where every smaller circle rotates faster than the previous then copying it downwards and tapering it to make the typical "hole" that is formed. I previously made a mistake where i copied the volume created from the effect and put it as the source of the water and got it working but the surface water was stationary, now that i have the surface moving but when I let the effect run it only "spins" the top layer of the water and doesn't go any deeper into the water , any tips? or any help would be appreciated. Whirlpool13.hipnc
  2. Hey everyone! I've been digging through the forum but quite haven't found something that will help me get this effect i'm trying to achieve. i'm trying to work on an setup where I have particles stuck on a deforming grid and the particles become unstuck as they inherit velocity in Y(sop solver) and then with gravity they come back down. my current setup might be too complicated because it's proving very difficult to control. i am using a popnet where particles stick to the collider geo and become unstuck with a sopsolver "if (@Cd.r > .1){ @stuck = 0; }" does anyone have ideas on how to simplify the setup? is this something that the grain solver would be better at handling? thanks everyone! waveRipple_v003.hip
  3. Hi guys, I'm very new to Houdini. I'm coming from a Softimage ICE background so my brain is still struggling with adapting to a new workflow so bear with me if you can! I was following this awesome tutorial from the Entagma guys (linked bwlow). In short, I replaced the spheres he uses at the end with the trusty ol' pig head and now I would like to figure out how to make these pigs heads turn in the direction they are moving as they slide around the surface. I've spend a long time googling and looking at previous posts related to particle orientation but I can't seem to find a way to adapt anything to this scenario. I'll attach the scene file if anyone has any advice? I think I would need to do something like finding the point position from the current and previous frames and subtract them to create the direction vector but I can't find a way to do that in any of the PopVops. I tried using a PopLookat and setting the target to look at the velocity but not luck. Any help would be appreciated. I'm not great at VEX, I come from ICE so Pop Vops etc work best in my brain if thats possible. Cheers (not sure how to reduce size of video in this post, apologies if it shows up giant!) Entagma_GrowthEvenOnSurface_V01a.hipnc
  4. Hi, I have a question about copying velocity's to a flip simulation. I want to create a specific shape in the motion of the fluid. The only way I can get close to that at the moment is to source(copy) a generated velocity into the flip sim. That's because when I add the velocity, it overshoots too fast and I can't get that specific shape out of it. The only thing with copying the velocity, is that it copy's the velocities with a value of 0 as well, so the flip is completely at rest. I was thinking that this could be fixed with a mask field, but it doesn't seems to work as I expected. Is there anybody out there who can tell me what i'm doing wrong? Or other suggestions to get that result would be welcome as well! Actually, any help/advice would be appreciated! pumpVelToFlip.hip
  5. Alembic Velocity Issue

    Hi guys I am having a rather strange issue. I have a particle system which is advected by volume from a pyro sim, and then I have bits of geometry copystamped to this system. But when I export this to Maya with ROP Alembic I am not getting velocity. What's strange is if I do a convert to points from volume using the original pyro sim, copystamp that and export it instead... the velocity works in Redshift Maya.. why does it break when using points from pops? Does anyone have an idea about what's going on? EDIT: Found a workaround. Convert the velocity to colour in houdini, and use it as the motion vector source in Maya mesh controls.
  6. Hi, I am currently creating a simulation with flip fluids that are affected by a vortex force. I need the velocity/lift attributes to be animated independently throughout the simulation, though no matter how I set the settings for either the sop geometry, or vortex force operator, the values will not change throughout the simulation. What is the proper method for animating these attributes for use in dops? Thank you,
  7. How is it possible to convert a single volume, to 3 volumes (velocity) I have shaped form that I am converting to a volume. I then need to convert that volume to vel.x vel.y and vel.z, to create a velocity field of. it is not optimal to just create a bound and then convert it via a "Volume" node, because I need to keep the original shape.
  8. Fast smoke simulation

    Hi there, I am learning about smoke in houdini and I am desperately trying to achieve an effect like this By this I mean a fast paced smoke puff that spreads out wide, like almost in a V shape. However, no matter what I do, my smoke always ends up looking very straigt. I can achieve the fast paced but then it looks even more straight I think. I tried making it faster by chaning the time scale, giving it a high buoyancy lift, using my normals as a velocity volume (in source volume node) and setting the scale of it to very high, setting the temperature scale to a higher values, etc. All these individual things work for the speed, but I keep ending up with quite a straight line, or something that isn't making sense at all. I tried adding turbulance, but this also doesn't help me to achieve that "v shape". I hope someone can explain to me what is going wrong, because I am totally lost.
  9. Hey magicians, I'm working on a flip river wich I need to have color attribute, followed H16 Flip Masterclass and get there, but then I tried to add color in several ways but I can't get it working. I tried adding a sop solver to dops with attribute transfer, but the color didnt worked on the motion. Also tried making source volume with points from volume with uv texture but velocity gets weird. Working river without CD Cd particles with weird velocity Any tips on how to fix this? attaching a hip. Thanks in advance flip_issue.hip
  10. disturbance when velocity

    Hi, Is it possible to have disturbance added only when a pyro sim is moving? I have a cloud being moved by a plane. Regular disturbance with default settings in pyro solver causes your sim to move. I don't want the disturbance to cause the sim to move, I want it to disturb when the sim is moving. I tried changing bindings, etc. but I couldn't get anything to work. Any suggestions? Thanks
  11. velocity field question

    hello guys, I tried to get velocity field in to POP and use advect by volume. but particles stop moving when they reaching some position. I can't find the reason of it and how to fix it. Does anyone can help that for me please? vortex_field_problem.hipnc
  12. Hi, The picture shows an object , create > test geo > add velocity > vdbFromPolygon with vel field > visualize velocity. I wonder how to split velocity to tangent velocity and normal velocity. I guess we don't have a node to do it by one click, and need to work on volume vop/wrangle. If anyone knows how to do it, I will appreciate it, thanks!
  13. Hello everyone! Even though I've had many help on odforce it's my first time posting. As the title says I'm trying to figure out how you would use particle velocity to increase and decrease the speed of a looping animation. I have done it with a copy stamp but I was wondering if there is any other way around it. Thank you in advance
  14. Hello, I have a feeling this is a common issue, but its a bit hard to explain / search for a solution. I've imported an animated alembic file, used unpack to get the points and put it through a trail node to get the point velocities, the problem is that the point count changes as some of the objects "disappear", so you get brief flicks of extreme velocity as the point IDs shuffle, I am curious about the method(s) for dealing with this problem.. Thank you
  15. Hello everyone, I have a problem on rendering bifrost surface in maya 2018,this is my render test: I have the velocity pass and displacement map output by Boss, but how can I render mesh by velocity? It means that the splash which with high velocity will be rendered with no displacement, and the other part of mesh which with low velocity will be rendered with displacement, I just want to render the surface with no thickness, how to cut the mesh in rendering? so I can render the mesh just like this: or is there any other way to render mesh? I want the splash is rendered with no displacement, and the other part of mesh rendered with displacement, and the mesh will be combined with outside infinite ocean, which can be rendered with the same boss displacement map. This is my RnD: Can anyone help me? Thanks!
  16. Hello everyone, I have a problem on rendering bifrost surface in maya 2018,this is my render test: I have the velocity pass and displacement map output by Boss, but how can I render mesh by velocity? It means that the splash which with high velocity will be rendered with no displacement, and the other part of mesh which with low velocity will be rendered with displacement, I just want to render the surface with no thickness, how to cut the mesh in rendering? so I can render the mesh just like this: or is there any other way to render mesh? I want the splash is rendered with no displacement, and the other part of mesh rendered with displacement, and the mesh will be combined with outside infinite ocean, which can be rendered with the same boss displacement map. This is my RnD:
  17. Hello All, I'm newer to Houdini, and working to jump into setting up some simple/fast solutions for wrapping particles around a mesh. Not sticking to the mesh, but flowing over. I'm a professional Nuke compositor with general experience in Maya, so will understand most terminology, but certainly completely new to Houdini, so open to all suggestions and breakdown's of the principles. The end goal is to drive a curl noise vortex up in Y, and place geo within the field that the noise will wrap and flow around. I have attached my test HIP file. I've been trying to combine this tutorial's use of the cross product and XYZ distance, with the VDB setup from Entagma's Curl Noise tutorial. Other than there being a good possibility I'm on the completely wrong path for this type of effect, it seems I may be confused on properly using the cross product in the VolumeVOP. The attached file doesn't touch properly adding or multiplying in the curl noise, because I want to correct my issue with the field to begin. Thank you all for your time, patience and help. My Best, Josh curl_noise_trailsTest_003.hipnc
  18. Hello Pals, Hope you all are having a great year so far. I am trying to do a shot with particles which needs slow motion on a certain camera moment. Basically, I just want to slow down the motion of my particles for few frames. I dont want to mess with the velocity etc as I really like the motion of my sim. I looked into time-shift, time-warp etc. But they always feel like a cheat and not much of a high quality solution. There is a "Scale Time" option on the POP net. But for some odd reason its locked and we cant key-frame it at all. That would have been the best solution, where we can just lower the timescale for bunch of frames and then resume it in normal speed. Can anyone just give me a brief why Sidefx would want to make this such a big deal and lock it on POP nets? Thank-you and have a great day! HD
  19. Hello ! Is there a simple way to transfer velocity attributes from a volume to another ? Or create velocity from scratch ? Thanks !
  20. Hello everyone... I have a problem with an RBD packed object inheriting velocity. In the file, I have the attribute active being set by another object, but the velocity doesn't kick in at all. The velocity works if I remove the point wrangle setting active to 0 and remove the sop solver. If I try a pop vop or a geo vop, there's some weird velocity behavior that happens. If I tick on override attribute, the velocity takes off big time and doesn't appear that gravity takes hold. All I'm looking for is initial velocity once the pieces become active. I saw a few threads on the side fx forums and this forum, but nothing I saw seems to be working. Any thoughts? test_active_velocity.hipnc
  21. Hey everyone, I really fell in love with some of the visuals created by Chaotic Atmospheres, link : http://chaoticatmospheres.com/flowing-city-map. They describe their process as a mix of displacement maps created in world machine all composited in PS, but I want to create and simulate this with velocity flows and possibly particles to create a more dynamic map for some of my architectural site plans. I've looked through and gathered different techniques for creating vector fields and I am a little stuck. I've used some of the techniques with manuplating vector fields with curves, creating a volume and driving trails, but the collision and erosion just hasn't produced the effect I want quite yet. With a few drawn curves on the grid, I can get a nice flow, but upon adding any more complex nurb systems, it just starts to group too many vectors. I might be going about all this wrong, but wanted to see if anyone could offer some more help or a more efficient technique. The end goal would be for the vectors to be able to be animated to visualize flow from the city boundaries outwards towards the edges. Thanks to anyone who can offer any advice/tips/help on this endeavor.
  22. hi guys as the title says really i've got an anim i imported - i dropped down a trail sop compute velocity and now i want to turn that into normals. I tried attribute promote and a wrangle with @N = @V; but it didn't seem to work can anyone advise me how to go about doing this? end result is having some control of a pyro sim around a character eg smoke swirling up and around his limbs so i'm using a tip by Ben Watts to try and blend those animation normals/velocity with normals that simply face upwards. Theres probably other ways to do this but i've no idea and tbh this whole thing is just an guessxperiment heh heres the tut i was looking at....
  23. Volume Velocity to Mesh?

    Hey guys, I'm growing some objects using volumes (scene is attached) and I'd like to have motion blur on the moving/growing areas. I do have some velocity on the volume, in order to control it's growing direction, but i have no idea on how to transfer it to the mesh itself. here's how the setup looks like: Thx Volume.Growth.Velocity.v1a.hiplc
  24. Is there a way to calculate the angular velocity from spinning points that only hold "N" "v" and "up", without using the trail SOP?
  25. Applying vel to cloth through sops

    Hey, still playing with the FEM cloth model in Houdini. Found that applying forces through the drag model works much better in terms of simulation quality. So I generated some vel field in sops and imported it into dops. Unfortunately the velocities aren't affecting anything. I took the sails asset from orbold as an example but still something isn't willing to wor. Hope someone has got an idea. Attachments: vel.hiplc
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