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Found 105 results

  1. Hi; I would like to add some velocity to particles from a volume (smoke), so I tried to use "POP Attribute from volume", but it doesn't work. How can I fix it? Actually, "POP advect from volume" works, but I would like to ADD/Multiply the velocity to particles, not advect them. Thanks for helping. POP_Attribute_from_Volume.hip
  2. Hello, I asked the exact same question in the official houdini forum and got no answer yet, hope that's no problem I'm trying to make an object follow a path created from points (positions imported from an external file) with a velocity based on the distance of subsequent points. I used the method of creating a line from the points and constrain the object to it. Then I calculated the distance between subsequent points in a wrangle inside the path-geometry node and stored it as a velocity attribute. My idea was to somehow “channel” the velocity to the position parameter of the constraint path, but I don't know how to do that. I'm new to houdini and therefore assume there is a much better way to do all of this. Maybe one can create an entire animation path with the velocity information directly from the imported point positions. Reading several documentations about velocity attributes did not help… Thanks, Lukas positions.csv simple_pendulum.hipnc
  3. Volume shaping in dop network

    Hi guys! Recently I was asking for some advice on how to deform spherical parts of volume into different shapes (in my case skulls). And here is the best reply I've got: "You need a dop I/O node - target your dop network and then point it to your smoke object. Add an import field with the little plus button and import the field named "Pressure". This value is very small but if you use volume visualize nodes or volume vops you can fit the values to pull out the pressure range where these mushroom shapes occur. Once you know the range (usually somewhere around 0.02 to 0.00 for these shapes) you now have the correct mask range. You can now set "Pressure" as the control field in your disturbance tab on the pyro solver. Just make sure you use the correct range, then you can dial the strength of your disturbance applied in only the areas highlighted previously in your volume visualizer. One thing to note - if you want to identify them each you're going to need a sop solver. Once you have the pressure field isolated, you can convert the vdb to poly and use connectivity to seperate them out and then pack them to get a centroid for the specific mushroom. But you're going to want to blend the point position of that centroid over time as it may jitter or pop in and out of existence depending on the tightness of your isolation range. Once those points have a history they'll have velocity and direction you can use to orient your custom field that warps it into a skull or whatever." However, I'm stuck on the last step where I have to setup sop solver and feed the output back in a sim. I would be very grateful for any advice or more detailed instructions on how to set the last part up P.S. I've attached a basic setup file in case if needed sklsmk_test.hipnc geo_02.0001.bgeo.sc
  4. Vellum Force/Impacts

    Hi there, I'm trying to acheive an effect in vellum that blasts holes in preTorn cloth. I'm relatively new to Houdini so have been following the Applied Rigids V where I created nice impact blasts of particles along a curve every 4 frames, but I really want a way to apply that force/velocity to my cloth. Any advice, ideas or alternative approaches would be greatly appreciated! Huge thanks, Al
  5. Hey folks, I started with Houdini very recently and I wanna focus on fx at first. So after trying with the Shelf tools I wanted to stylize my sims. I looked around the web and followed tutorials on a particle based pyro sim (I wanna do an explosion). The problem is, the pyro sim won't work with my PoP really well. I considered that my particles are too fast maybe and added substeps. But that didn't work out either and I don't know how to fix this thing. I hope you could understand my issue. Help would be much appreciated :^) Impact explosion.hipnc
  6. Hi there, So I'm trying to fit the point velocity attribute range from 0-1. In my test scene, I have a simple RBD sphere shooting upwards and slowly slows down once landed. I'm using the length of velocity, promote it to detail attribute with min and max v and imported the detail attributes in a second wrangler where I fit it in an attribute called @speed, the issue is instead of @speed going from 0-1, it always starts at 0.5? Or is my setup wrong? Thanks. *hip file attached* min_max_v.hip
  7. Hi everyone, recently i had a look into vellum and tried to make an emitter of soft objects colliding each other as they go. I know it does exist the setting "Emission type: continuous" which generates a copy of your geo and constraints periodically, and it works like a charm when you basically just want them to fall one over another. But this system seems not to be affected by external velocity, as for example do does a simple setup of multiple rbd objects. I was particularly interested in this because i want my objects to move with a random velocity, in a certain direction, within a cone angle; and i set all these properties in an AttributeRandomize at sop level. So, is there a way to feed this external velocity into dopnet, like you do with inherit velocity in rigid bodies? Plus, i know there are several methods to emit multiple rigid objects, using Packedobj and PopSource or the SopSolver and Rigidbodysolver combined with Multisolver. They seem clear and simple as hell, isn't there a way to make a similar process into a vellum driven dop? Attached below the hip file, with two examples of multiple rigid body emitters, which i can't replicate with vellum. Hope it helps. Oh, and i suddenly thought about vellum, but if there is another smarter method to do this (ie FEM...?) please let me know! Many thanks emitting_multiple_vellumobj.hipnc
  8. Hey guys, I'm watching this talk by Will McNeil, he created a great oil painting setup that I'm trying to study it. He made clusters from a image, then traced and made lines inside, I'm struggling in this step, to get the trails inside the contour: Here's his talk if anyone want to checkout: Any help to get these contour lines inside will be super helpful Thanks!
  9. Hi everyone!!! Started to study houdini. I have separate elements with velocity setup as I want, but couldn't find a way to add any one of them to drive flip fluid. How can I add a velocity of the mesh or curve or the volume to the flip fluid? Or maybe someone can share a tutorial about how it works? In the end trying to create a chocolate swirl or vortex. Thanks.
  10. How to add color gradient through velocity plus collision to influence color velocity? to influence the color such as this one here: https://vimeo.com/59024762 how did he do, but he used xsi softimage. if possible to make a Houdini?
  11. I'm wondering why this custom velocity is not work? I have tried various methods, but I'm not sure how....
  12. Particles do not move well

    Hello. I'm making a blaster referring to the tutorial. But, it stopped at the first stage of moving particles. For some reason, the particles get stuck without moving. I tried to increase the velocity, but did not move. Could you tell me who will attach the file? Could you help me... blaster.hiplc cave_cache.bgeo.sc E 45 Aircraft_obj.obj
  13. Hello; When I use scattered points as a POP source, how can I apply velocity to some group of points, dynamically ( during frames, not just at the initial frame)? I know that I should apply the velocity force inside the DOP, but I don't know how Thanks for helping. Add_Velocity_to_particles_01.hip
  14. Hi Guys! I am having a issue with crowds. So in the simulation have setup I have set the velocity and heading to be random in the crowd source. Although there is a specific agent I wasn't to direct where to start walking. I am finding that this isnt possible if you have set the velocity and heading to random in the crowdsource. I have attached a file, apologies i have baked the agent into the file so its little larger then i would like. Any ideas would be greatly appreciated Thanks!! Josh CROWDDIRECTIONTEST.hip
  15. Vector Field HDA bundle

    Hi folks. Just posted a set of HDAs geared towards building vector fields intuitively, using curve and point features. Documentation and alternate download can be found here. Happy trails! DFX_Vecfield_HDA_bundle.zip
  16. 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
  17. 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
  18. 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?
  19. Hi; In a DOP network like image below, how can I import point velocity attribute, into DOP net? Thanks for helping. DOP_Velocity.hip
  20. 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
  21. 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
  22. 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!
  23. 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.
  24. 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
  25. 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!
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