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Found 54 results

  1. 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
  2. Hi, during the work with my maya alembic reader, I discovered a problem with alembic files written by houdini. Obviously Houdini exports an additional point geometry together with my mesh. If I load the alembic in Maya, I get a mesh shape and a particle shape. In houdini I can see two packed objects in the alembic sop. This only happens in certain situations. e.g. if I create a box and deform it, only one packed object is created in the alebic export. Only if I export my flip mesh an additional packed point geometry is exported and I get a warning in the exporter: "Renaming node to /geo1/file3_1 to resolve collision". Does anyone know what's going on here? It seems not to be a new phenomenon, it happens the same way with H16.
  3. Hi, I'm trying to replicate the way you can set color for a particle's "initial state" in a Maya particle system. I've looked through docs, tuts, etc, and have not been able to get this to work: Here's what I got so far: ---------------------------- I've scattered points over some terrain Geo, used a point Vop to create noise based color for the Cd attribute on the points, then used the points as the initial geometry in the popObject. The idea is to have textured "dust" blow over the Geo (I'm driving the pop animation with a Pyro sim). The animation works well, but I can't figure out how to transfer the Cd attribute of the scattered points to the particles. I played with creating the color with a PopVop in the Dop network, but the color is assigned by position so the particles animate but the color does not. I've attached my test scene. I'd appreciate any clues; thanks in advance bcs_partDustTest_v01.zip
  4. I have a popnet creating some particles with the POP spin, to have a random rotation in each particle, also Im copying a tube in each particle, the tube rotates as it supposed to, but when they hit the ground, the tubes stays with a random rotation as well instead of pointing Y. I'm thinking that if I use the normals instead of the POP spin I could blend between the N0 and N1 when the particle hit the ground, using the hit info from the POPnet, but truthfully I don't know how to achieve this .-. I'm using POPs and copy the tubes/coins to the particles because the particles born magicaly from the floor after a character hit the floor with his cane. If anyone could help me or have any idea I would appreciate it!!!
  5. Delete particle

    Hi, I'm a student learning houdini. I'm working with particles and I want to delete just few of the points that I choose. I tried to use particle ID but because of the life expectancy variance, the id keeps changing and I couldn't delete the point. So, for the same reason delete SOP doesn't work too. (It only gets deleted in the specific frame which I selected the point) Are there any resolutions of deleting particles that I want to delete? I've also seen an example hip file in odforce that uses 'for loop node' in VOP but I couldn't try that way because it doesn't work in houdini 16.
  6. Particle rotate based in friction

    Hi guys I have a question that is breaking my headoff. I have a simple set up, I have a ground to collide and is scattering points in the surface , based in the distance threshold of an animated geo, I created a group based in an attribute, also have the N and v set up. From this group I'm creating particles to simulate some kind of debri left behind of the falling "rock". The particles when are born they rotate until they hit the ground, but not when are falling or "sliding" in the surface of the ground. I have a POPGraings that give me this nice falling/sliding look. Any idea on how to get the particles rotate based on the friction or contact with the ground surface? Thanks for any idea you can give me
  7. fill mocap volume

    Hi all, I'm working with some mocap meshes that I'm trailing particles over using the 'minpos' technique in POP VOPs. I'm getting a little stuck though, as when i make trails of the particles, these obviously trail behind the mocap as the keep their birth XYZ coords. What I'd like to achieve is that the trails adhere to the surface of the body/geo in the same way that the particles do, so i end up with something like 0:24 > 0:26 of the attached video. Maybe I need to do something within a sop solver? perhaps dop pop is the completely incorrect way to go? Any hints or tips greatly appreciated - I've attached my .hip here should anyone have the time to take a look! Thanks! (hints on filling the volume as-in the video will also be met with rapturous thanks... I'm not even sure where to start with that one.) surface_particles_trail_test.hip
  8. Hello guys, i have a serious mesh flickering problem in my flip simulation. The timescale in the flip solver has been animated to slow down the simulation. Looking at the particles everything seems fine, but when it comes to meshing and the particles are moving really slow, the mesh starts to flicker and holes are forming and disappearing every frame. I've tried increasing the resolution, lowering the particle separation in the particle fluid surface node (or vdb from particle fluid, i've tried that as well), lowering the grid scale or the particle radius scale, the flickering changes but it never goes away. any help is greatly appreciated thanks in advance slowmoving_flip_flicker.hip
  9. Hey all, I'm a compositing student but for a current group project we are to make a bumper and ended on doing it in Houdini because it just looks best. So I don't have much experience in Houdini before this except watching some courses/tutorials and playing around very little. The learning curve is quite steep and I've run into several snags. First of all I followed this tutorial to get the first morph/transition and things panned out pretty well. However I got a third model and maybe even a fourth and I don't know how to add these into the mix. In my current file there is just a simple blendshapes for the third model but it's quite uninteresting. That's it for starters at least. Other than that I'm trying to figure out how to change the colors between each model as well. The project file is probably pretty dank since it's my first project in Houdini. I really love the program and want to continue working in it! Hopefully someone out there could take some time to look it over and give some input. Attached is a .rar with .hip and the .fbx camera as well as x3 .obj models used. bumper.rar
  10. Hey everyone, I'd like to try and create a tire burnout effect where the smoke is emitted from the tire/ground contact point. The smoke then shoots out from the back of the tire based on the velocity of the rotating tire as the car goes in circles. I'm still a beginner with houdini, so I have an idea of what I need to do (I think) but I'm not sure how to go about reaching my goal. Right now I'm thinking that I need to get a contact zone for the tire's point of contact with the ground. Then I need to calculate the velocity of the spinning tire and send that to the emitting particles (which are emitting from the tire). The particles should then emit only when they're in the contact zone (so they mostly shoot out in the rear direction). Then I make it so only the emitted particles drive a pyro sim. I've attached a hip of where I'm at so far. I have the velocity from tire figured out, I just need to figure out how to get a contact zone and only emit particles when the surface of the tire is in the contact zone. Here are a few hip files that I've found during my initial research. I feel like the examples in this link don't give the best results for what I'm going for though, so I'd like to do this another way: http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=17139&view=previous&sid=b2857b8fc9d609b04ecb1cc6610e1c18 I'd like my effect to be similar to this example: https://www.youtube.com/watch?v=QcT3xSjaPv0 Here's a reference video for the final effect I'd like to achieve: https://www.youtube.com/watch?v=Pj8zdgHMtbU. Thank you! tire_burnout_odforum.hipnc
  11. Particle effect help

    Hello magicians, I'm stuck in a R&D for a client, been trying to do a particle behavior for 5 days without success. Heres a video gif of the latest client ref: http://i.imgur.com/dvtTkL1.gifv Also attached is some early image references the client sent but I would like to focus on the gif one. Here is a gif with some of my RDs, I tried advecting particles from pyro, doing a pop network with curve forces and some more stuff, the behavior the client wants is some sort of flock/swarm like a monster that chase a person. http://i.imgur.com/Bs9kFbK.gifv Thanks in advance Cheers!
  12. Particle scale

    Question about particle scale. All I did was create a location particle emitter. Then I converted the particles using the vdb from particles. Here is the question: What is the best way to control the scale of each particle, and what is determining the scale it is outputting to the vdb node? See how big the particles appear to be in the vdb picture? Thanks
  13. Particles collide inside a mesh

    Hello everyone,Sorry for the basic question but I just want to emit some bouncing balls inside a mesh with Houdini 15.5. To create that I just create a source particle emitter and I put it inside my collider mesh. I make the mesh a static object and increase the uniform division and click on invert sign in the static object node. But when I launch the simulation the particles have a very strange behavior. If anyone have some idea to achieve this.Thank you for your response. animation_particles_gpe_v003.hip
  14. Hi everyone, I'm an extreme beginner when it comes to Houdini, can someone please tell me how to make some falling particles more bouncy when they come into contact with a ground plane? Thanks!! I've attached the file Ball Pit Ball Simulation 011.hipnc
  15. Audio affecting particle position

    Hey all I'm quite new to houdini so please bare with me. Is there a way to use an audio output from chops to change the position of a particles? Can I do that by using a pop vop? If so, how can I import my chops output in there and add it to the position of my particles? Is there maybe a better solution for that? Thank you!
  16. Particle Explosion

    Hey, I can't figure out how to emit particles in all directions from geometry. I mean, when you emit from geometry it does go in all directions, but how do you multiply that speed? I messed with particle variance, and it seems to work except for the fact that turning it up moves the particle on the first frame. In maya, there is "away from center". I turn that up, and particles shoot from the center outwards. How do I do that here? Thanks
  17. Wires on Particles?

    Hi everyone, I'm trying to use the points created by a particle sim, and copy lines to them, then solve them as wires. However, so far I can get nothing to work at all. Nothing ever shows up the in viewport, I don't know why. I have tried using one dop network to create the particles, and another to solve the wires, but this doesn't work. I suspect it's something to do with the fact that the newly created geometry needs to be imported into the DOP network, but I do not know how to do this. Any advice would really be appreciated. Wires_on_Particles.hipnc
  18. particles path circle

    Hi guys! I've made a sim with particles but I would like to keep them rotate in circle for some seconds and then use their inherit velocity. how i can keep them rotating? i've been trying to add angular velocity with cos ($T * 180) ty = sin ($T * 180) this expression, but doesnt seem to work. any suggestions? thanks!
  19. WhirlPool Attempt

    Hey guys i was wondering if any of you could give me some guidance on a whirlpool simulation ive been working on. I can submit the file if anybody would like to look at it that would be awesome. I guess the main problem im having is determining how high of quality i need to make everything. For my project in school we are using maya and arnold. I have the Rop output nodes setup and i think i have a feel for how to convert it to an alembic and importing it to maya from there. Any tips that anyone can provide would be great. whirlpool_v021.hipnc
  20. Hello, I'm trying to control some particles, I need them to travel on a ground, toward an object, then creep up on that object surface, when they reach it. I've tried a few method (creep, ray, slide on collision ...) but even if I manage to have them slide on an object surface, my problem is how to set up the POP network in order to have them transitioning from one surface to another. I've cheated with a P.y = 0 in order to have them on the ground with ease, but I'm failing at controlling a nice transition from ground to object. here is a basic setup, without much, in order to not restrict the different approaches . Also, I'll replace the particle with a small disk later, so I think I need them (particles) to be oriented properly. Thanks for any advise and help! prtcl_slide_4OD.hipnc
  21. So I've been trying to get the grain solver to use animated geometry as an emitter but I can't get it to work. I'm trying to create a sandman effect like this http://forums.odforce.net/topic/11658-flip-fluid-sand-girl/?page=1 but I cant get it to work since the project is quite outdated. The problem is that the creation frame occurs on frame 1, and If I change it, to say 1-10, it wont give me the effect I'm looking for, I moved from 3dsmax to houdini 1 month ago so be simple in your questions if you can
  22. particle "beam"

    Hello Houdini Masters! I'm having trouble with finding a starting point for creating a beam of energy being shot out of the barrel of a weapon. I haven't worked with particles much, but I don't really understand how all those particles become something so clean as a solid beam of "energy". I have some reference as to what i would want the beam to look like: (lilo & stich - the green ray from Jumba's gun): (WoW: Legion trailer - Sylvanas's arrows she's shooting) If anyone has any links to tutorials, articles explaining the process for this, or has any first hand experience working with partcles/"energy"beams your help would be most appreciated. Thanks in advance
  23. Water dripping

    Hi guys I'm trying to simulate a dripping effect like the attached photo but my object is a sphere which doesn't have a concave surface and it can't hold water. So do you know a way that I can emit flip from the wet surface of the sphere in the way that look likes it is drying for few seconds? I tried emitting Flip from object but it emits from a SDF and its nothing like this dripping. Thank you
  24. Hey guys, first post here. I'm extremely noob at Houdini and I've got a very basic question. I've got a particle system going, and after the POPs system in the Source Particles SOP it creates, I'm trying to use the Y position of each particle to drive a Blend Sequence that is copied onto the particles with a Copy SOP. What I haven't been able to find is how to query the Y position of my particles. I can find their positions with the Geometry Spreadsheet, but the name of the attribute it gives me is "P[y]", and typing that into an expression doesn't seem to work. I had thought it might be "@P.y" but that errors out as well. I think one of the problems is that I'm not telling Houdini WHAT to find the Y position of. But again, not sure how to find that. I've googled and did a cursory search of the forums here but all the posts I've found are way more advanced than this simple thing I'm trying to find Can you fine gentlemen/ladies point me in the right direction to find how to query this sort of basic data? wk2_copy.hipnc
  25. So I setup an easy Particle system on Houdini, and when I try to Alembic it doesn't works, just FBX does. Can anyone please make an easy Houdini file with all setup for Alembic ROP a particle system?, so I can see whats the diference between it and mine. (I cant share mine because the source is a Bgeo sequence of 360 files) Im on H12 and trying to export alembic to Maya 2013 x64
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