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Found 48 results

  1. Hello ! Is there a simple way to transfer velocity attributes from a volume to another ? Or create velocity from scratch ? Thanks !
  2. 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
  3. 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.
  4. Hi Can someone shed some light on how to render a velocity pass, from a flip fluid vdb mesh, for compositing? Here's a reference videos:
  5. 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....
  6. 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
  7. Is there a way to calculate the angular velocity from spinning points that only hold "N" "v" and "up", without using the trail SOP?
  8. 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
  9. Hi. I am a beginner in Houdini studying in Korea. I have not been able to find a way to do this all day. I created a snow that flies quickly with particles. After rendering the mantra to the snow I want to give a vector blur in Nuke, but it is difficult to draw a pass. I can not continue vector blur in velocity direction. How do I make it look like a picture? I have not found it in a few days. Please help me.
  10. Turn vel streamers into usable curves

    I want to jack the streamer visualizations from my fluid source and use it to extrude shapes along. Is this doable? I want to do this because of how cleanly the streamer lines are distributed within a volume.
  11. hi everyone, i have a destruction cache from maya, i use trail to compute velocity and transfer to speed; i group some points base on speed (e.g speed >= 8), and scatter to generate smoke; but speed keep changing, if the point speed less than 8, i will lost it and result in my smoke trail is broken... so how can i constantly keep these points if their speed is greater than 8 once?
  12. Get Sop Vel to pops

    I'm trying to find a way to get bring in the velocity from a field i created in sops into pops directly. I can do this easily in dops with a sop geo and a particlestofield node, but i can't seem to replicate this in pops. I've seen this done before in a pop wrangle, but I don't know the code myself. Can anybody help me out?
  13. FEM Alembic - Angular Velocity not Centered

    Sup guys, I've just imported an alembic from client - it's just a static object - and it's already placed a few units up from the ground. I need to give it some initial angular velocity to make it spin while it falls but, it looks like, the angular veocity is coming from the origin gnomon. Thx /Alvaro
  14. FEM Alembic - Angular Velocity not Centered

    Sup guys, I've just imported an alembic from a client - it's just a static object - and it's already placed a few units up from the ground. I need to give it some initial angular velocity to make it spin while it falls but, it looks like, the angular veocity is coming from the origin gnomon. Thx /Alvaro
  15. Packed Objects InitialVelocity ???

    Hey guys, in rbd packed objects if we turn on inherit velocity from point then it does this only on the creation frame, what if i want to assign some velocity only when active=1, how can i override the inheritvelocity parm. Any help would be appreciated.
  16. Smoke Density Driven By Velocity

    Hello! I was working on a basic smoke sim where the smoke was being emitted from animated type-geo. I computed the velocity of the geo with a trail, then plugged that into the fluid source to create the density for the smoke sim. That is all working fine as you can see in the render. However, I'm not happy with how the smoke just appears all at once. In other sims I've used an attribute wrangle to map the density to a ramp and have the density fade in but in this case I want the smoke density only to be generated when the velocity starts to increase. I played around with trying to get the velocity data out of VOPs but I really was just taking stabs in the dark. Any suggestions would be appreciated. smoke_test_v02.mp4 text.abc smoke_density_v01b (1).hipnc
  17. Hey, I'm curious about different approach for artistically control the creation of a velocity field. I've learn how to make nice noisy, curly etc.. fields, but when it comes to controlling them more, how would one proceed ? could some curves be used as general guides for the velocities? And the perturbed slightly by some noise ? I bet there's many ways to do it, I've seen some nice VolumeVOP work in some tut (volume trails), but I wondering about the best way to get real control. thanks in advance for any input
  18. Pops following animated mesh

    Hello everyone ! Does someone know how to use an animated mesh for driving some velocities of particles ? I have done a sim that I like but I want it to follow the character's animation... The particles born in the chest and goes to his head which is rotating... I'm pretty new to pops, I think that maybe I can make it move through a pcopen but maybe it is a bit too much for what I want to do ? Also, I'm not pretty sure about how to make it... Maybe it's possible to feed the pcopen with a scatter of point on the surface of the character ? Thanks a lot and have a great day ! (Once finished and online I will try to post it as a comment !)
  19. Hello all, Any idea how to add velocity to a growth propagation ( from bwdesign tutorial ) ? Here is a sample file, I don't know what to do. I would like the points to have velocity ( in the direction of the growth... ) thanks. Here is a sample file without velocity of course growth_noVel.hip
  20. Hello everyone. I am doing a FLIP sim where I have a jug with liquid, add some custom velocity to make a vortex like movement of the fluid and then cut them so the fluid can go to rest. As you can see on the screenshot, the fluid is loosing volume. Is there a way to retain the original fluid level withouth adding some extra emitters? I am guessing probably the solver is killing some of the particles. Thank you.
  21. Particle velocity based on age.

    Hey guys. Quick question here. I have a simple particle sim emitting from a sphere in a direction. I want the velocity to decrease as the particles get older. how would I be able to achieve that? Some of the particles are already born at frame 1 (I have a preroll on my sim) and this needs to apply to them as well. Thanks for the help, and thanks for an awesome forum. Cheers
  22. Hey guys, My scene right now involves an octopus tentacle slamming down and destroying the middle of a ship. I shattered the ship and added angular velocity in SOPS to the shattered pieces, which is then brought into DOPS with the 'inherent velocity from point velocity' option. I then added an 'rbd key activate' to activate once the tentacle hits the ship. The problem is the whole center of the ship is exploding out at once from the inherited velocity. Is there a way to only activate the angular velocity apon collision with the tentacle as it moves through the ship?
  23. Sand collision

    Hello everyone ! I'm trying to get an object impact sand. To achieve this kind of effect I planned to create a setup based on this great idea: https://vimeo.com/155198661 Here is what I have so far: Unfortunately I lack the maths to go further. What I need is to spread my velocity vectors outward from the collision mesh and also to remove any vectors that are "BEHIND" the motion. I was wondering if there was a way to ramp down the density using a volume VOP and the BB attribute but no luck so far, or find a way to emit more grain at the front, avoid a constant emission within the volume. Do you guys have any suggestions ? Cheers ! sand.avi collide_setup_01.hipnc
  24. FLIP Velocity by Normal

    Hey guys, Is there a way to control the FLIP's particles velocity based on the normals of a scene object? To be more specific: I have this grid and as soon as the particles get closer to it's surface, the particles start flowing on this grid's normals direction. Thx, Alvaro FLIP normal vel.rar
  25. Hi, I'm looking a way to emit particles from an alembic and that the particles will inherit the alembic velocity. My issues is that when I store the alembic point > add velocity, the v variable is always 0. So I'm guessing that is why my particles don't get push by the inherit velocity. I have also set the particles to inherit velocity. thanks for you help guys, Eric
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