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Found 90 results

  1. Hi; In a particle fluid simulation, I add velocity using "point vop". The problem is the particles start to move very fast from beginning, but I want they start to move by ease. How cant I increase particle's speed (velocity), over time? Thanks. Fluid_Velocity.hip
  2. I want to make water from the hose. Like a fire truck, very strong and fast. I tried to use a popslover, but it didn't look goodon the colision side and it didn't speed up properly when I tried to use flip Solver. I tried to bring the location and speed of the particle to flip Solver but it didn't work. What should I do? I'd appreciate it if you could help me. thank you
  3. Hello, I have noticed something interesting which I don't understand, but maybe somebody out there does. I created a Wave Tank shelf tool then a sphere and I hit the Deforming Object shelf on the sphere. Now I'm checking the OUT_INITIAL_VELOCITY node with PointsFromVolume and volumeTrail nodes. When I wire the collision geo into the collision input of the OceanSource node the velocity is become wierd as you can see, and it affects on the simulation in a bad way. It's just shelf tool! I didn't make any changes. I use 17.0. Is it normal or is it a bug or what is it? Is there anybody, who knows it?
  4. Hi; In a DOP network like image below, how can I import point velocity attribute, into DOP net? Thanks for helping. DOP_Velocity.hip
  5. trail velocity issue

    Hello Houdini folks! I have tiny issue with trailed particles. Is possible to visualize somehow it's velocity like in the picture in attach? Thank You so much for any advices and wish You Happy New Year!!!! vel_issue.hipnc
  6. How do you combine 2 velocity fields?

    So, I am trying to advect some particles around a torus with a 'volume velocity from surface', thing is, once they get out of range of the torus they just kinda stay there. So I am trying to add another velocity field to push them back, however I have gotten awfully stuck on this. In the example I have a torus with velocity and a box with all velocities pointing inwards, so how do I best combine these two? Also Happy New Year to all! vel_test-01.hiplc
  7. Hi everyone, Houdini newbie here! I'm trying to do a water/river sim where the water goes around the loop as shown below: Right now the particles are simulated with a flip object with velocity on z set to 0.5. How should I set up the velocity so the particles go around the loop? Or should I use an object to emit particles instead? Not sure what's the best way to approach. I'd really appreciate your help here!
  8. Hi; In case if we need to create an attribute for a simulation, what is right name for velocity attribute for Pyro, Fluid, Particles, RBD, simulation? "v" or "vel"? Thanks.
  9. Smoke from scratch, add force

    Hey dudes, I'm trying to build a simple smoke solver from scratch to understand more how they work. I created a simple setup with density, temperature and buoyancy. Now I want to add a second velocity volume as a force to my simulation. But when I add the force, the velocity is increasing massively in a few frames. I have to mix my force with the existing velocity but I don't understand how to do this my_solver.hiplc
  10. 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!
  11. Vellum Custom forces

    Hello, Can you please help me? I have a custom vortex force and I would like to apply it to vellum solver. How Can I do that? Thank you Gabor
  12. Hello everyone. I'm trying to emit particles from a rubik's cube which are solving himself. The problem is it doesn't look appealing because the emission is everywhere and without variations. I would like to emit the sparks only when the cube is rotating and only on the side of the rotation. Do you have an idea on how I could achieve this ? rubikSparks_01.hip
  13. Hi, I've object merge in my rbd sim and passing it through a trail sop to compute the velocity.The trail sop seems to be computing velocity before anything is moving in my sim,and the velocities are all over the place? Thanks a lot Josh
  14. VDB velocity half circle?

    Hi! Houdini beginner here. I have multiple curves that spin around that's being converted to VDB for smoke sim, but I'm getting this weird half-circle from its velocity. It almost looks like it's being clipped. How do I fix this? Thank you! vel_zero_on_z-axis.hipnc
  15. Smoke Sim- vel not coming through?

    Hi! Houdini beginner here. I created a custom velocity using pointVOP and added onto VDB surface attrib point.v as vel. When I middle-mouse click, it shows that vel exists. I have it scaled higher than 0 on the volume source in the DOP network and set "Add" for the operation option, but it makes no difference in the smoke sim. There's supposed to be a noise pattern in the velocity, but it's only taking into account of gravity. If I disable the gravity, nothing happens to the volume (the volume surface get steppier? but it doesn't push the smoke or anything). There's also a custom temperature going into DOP, but that one works fine. So I think I missed a step somewhere when bringing the velocity into the DOP network.....What am I missing? Thank you!!
  16. Here is a small test setup I've made. It is advecting particles along a curve, driven by a velocity field. I added another velocity field pushing the particles back towards the centre of the curve and blended the two. This is done by deriving a new field, based on a volume gradient and multiplying the volume gradient by the volume sample and negating it. So far, I haven't tested it much, but it seems like it is working, but the settings will certainly need some tweaking. As in Houdini, there are very often multiple solutions to the same problem, I was wondering if there was a different way of achieving this...how would you do it or improve it? advectPush.hipnc
  17. Hey folks, proud to present LYNX Tools, a collection of production proven open source tools to accelerate your workflows! All mentioned tools are free to download via the links below and are licensed with a full HoudiniFX license. All Houdini Assets have complete Houdini native documentation available. Repository: https://github.com/LucaScheller/VFX-LYNX Lastest stable release: https://github.com/LucaScheller/VFX-LYNX/releases Please give them a test drive, so we can improve them further Roadmap | https://github.com/LucaScheller/VFX-LYNX/projects/1 So far there are three tools: LYNX_force_general | Tweak your sims with this all purpose & intuitive force field. Built to mimic force fields in other DCC applications, but with support for more features and a natural Houdini user experience. https://www.lucascheller.de/vfx/2019/03/24/vfx-lynx-houdini-force-general-asset/ LYNX_fabric | Create fabric/weave patterns with ease. Perfect for creating that holiday sweater you never wanted. https://www.lucascheller.de/vfx/2019/03/16/vfx-lynx-houdini-fabric-asset/ LYNX_velocity | Get control of your velocities via an intuitive UI or groom them for absolute fine tuned control. https://www.lucascheller.de/vfx/2018/11/01/vfx-lynx-houdini-velocity-asset/ More info on my website, including full release logs: https://www.lucascheller.de/blog/ Houdini User Group Munich Presentation: https://vimeo.com/334887452
  18. Hello ! In order to setup my different Disturbances and Turbulences inside of a smoke simulation, I'd like to know what range of velocity I'm dealing with. How would you guys do that ? If you have the proper method to do that just ignore what's under. The sim is already cached (density, vel, rest, rest2). What I'm doing for now : When looking at the node info there is vel.x, vel.y and vel.z. I don't understand why but I've read that these are scalar values and has to do with how Houdini works so why not. I don't know how to inspect this volume further than that since it's a volume the Geometry Spreadsheet doesn't display anything. And when I apply a VolumeSlice I get 10 different vel attributes per point. vel[4] matches vel[7], vel[5] matches vel[8] and vel[6] matches vel[9]. But not the rest of the values. This is very confusing to me.
  19. Hi there, For a school project I am working on a river. I am getting very nice results with the standard flowmap tools already, but I wanted to change some things. First of all, I wanted the river to flow quicker where it is narrow, because velocity = flowrate/area. This does work. Note that to make this work, I went into the flowmap to color node and got rid of the normalize, because I want values over 1 for the speed. Then I also wanted the water to flow quicker, so I thought I'll just take v.y and multiply it with 9.81. This seems to work at first hand, but then at the top of the slopes of my river, the water seems to flow in the opposite direction (back up). I am not entirely sure why this happens. When I set the gravity to a lower value, like 3, this doesn't really happen yet (or at least not visible). Can anyone explain to me why this is happening? Also, is there a better way of achieving this result, rather than just not normalizing any of the vectors?
  20. source flip fluid with velocity

    hey! I'm trying to emit a flip fluid with some velocity, I can add a generic velocity in world space but in my case I want to add velocity along the normal of the object sourcing...just can't figured it out yet
  21. Velocity Field for Pyro

    Hi Houdini Friends, I'm having an issue with my pyro simulation where I've tried to setup a velocity field that changes the direction of the flame at a right angle, after several attempts I can't seem to get the velocity field to affect the sim even though the movement for the sim is sourced partially from my velocity field. I've attached the scene file, if anyone could tell me what I'm doing wrong it would be much appreciated scene.hipnc
  22. Hi, i am trying to achieve the reference footage and what is in the image. https://cgsociety.org/news/article/2788/fx-tips-and-tricks-with-andi-kadiu while debris is moving ahead velocity needs to be negate in pyro... as u can see in my playblast its looks simple trail(snaky behaviour in flipbook)....and if you see refrences there is specific pattern in the smoke some kind of circular trail(red color marked in ref image) leaving behind...i am struggling with this for few days....if anybody can help or put some information here that would be great....i have attached test hip file and refrences. kindly have a look..thank you in advance flipbook.mp4 pyro_trail_v001.hip pyro_trail.mp4
  23. Pyro Disturbance for high vel

    Hello, How to increase the disturbance on high velocity source, Im using particles and volume as sources, both with very high velocity, but disturbance only affect after some frames, not on initial simulation frames, I`m using 3 "gas disturbance" microsolvers, 2 controling density fields and 1 controling the velocity.
  24. I am trying to blow up multiple groups of particles in a sequence.(boxes of confetti exploding at different times). The activation isn't really the problem as I can use a sop solver within a dop to activate the particles group at different time. The issue is to give them that "initial velocity" at activation time. The only method i found that is working to achieve the effect, was to actually import and merge many popobject and "activate" them one by one in a sequence , with the velocity attribute created at sop level This solution is of course very inconvenient. I attached a clean file, with just the different group all popping at the same time. a solution to have them delayed one after the other would be very welcome I just can't find an elegant method which works procedurally. Thank you for your help confetis.hip
  25. 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
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