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Found 309 results

  1. Particles will bounce off a collision object, and I can influence that using the collider's Bounce parameter. Great. However, if I change my particles to grains, they will not bounce anymore, but slide. No matter what I do and this goes for pop grains as well as for Vellum grains. Settting ispbd to 0 is not a real solution, as this means I am not using PBD/Grains, anymore. Any idea? Here's a very simple test scene, using a pighead. Just activate/deactivate the POP Grains node in DOPs. collision_grains.hipnc
  2. Smoke follow (fast) animated curve

    Hey Everyone, i'm hoping someone could help me with this problem. In a nutshell, i need to move smoke down an animated path, so that it sticks really tightly to the paths animation, but with all the dynamism a smoke sim brings to the table, i.e. nice peeling away around all the edges etc - I have a fairly fast moving alembic curve - cached out with 10 substeps. (may not be needed but there if i do) - I am using pops with curve force to fire particles down the path, so they follow the curve closely. - Then im using the particles to source density, and also adding their velocity into the sim so that it makes the smoke move along the curve. - Im using a high dissipation value so that i can tighten up the expansion so you can really get a sense of where the curve is / maintain the shape. My issues lie generally in 2 places: 1. Where the animated curve is moving the most - the smoke / velocities struggle to catch up and i end up with a hard edge. 2. Where the curve is tangentially facing inwards in relation to the curve, the velocities 'add' the other way, also creating a hard edge. To try and illustrate what im after - if i could animate a regular smoke sim down a straight path and then warp it into an animated spline shape / spline wrap effect, this would be the best way to achieve it, but im really not sure if is possible - hence this approach. I have already tried upping substeps - but it didnt make any difference. My gut feeling is that the problem lies within how i am sourcing the velocity. I will point out that i am very much in my houdini infancy, so my ability to problem solve isn't great (yet!) Has anyone worked on a similar effect before, or does anyone have any tips/tricks/tuts on how to achieve what im after? Any/All help very much appreciated! Cheers, C SmokeAlongCurve.mp4
  3. Modelling Zen Stone Garden

    Hi there, I am a new user trying to get into the modelling side of Houdini after trying some simulation, and am currently working on a japanese stone/zen garden based on this image. I've found some great examples on how to create the stones (not worried about moss yet), but I was wondering if anyone out there had any idea how to create the combed patterns around the stones. I just finished doing some work with the ripple solver, but thats too realistic in this case. Ideally it would be something more simple involving grains or particles with instanced geomettry building up more based on a simple black and white image that i'd make in illustrator. Apologies if this is too simple a question, any help is very much appreciated. Thanks, H
  4. Hi, In my popnet, I want that, a new particle is born only if there are no particles in the scene. That is, suppose a single particle is born and dies after, say some random frame, only then a new particle is born. No new particle can be born even if a single particle is alive. How can I do that? Please help Thanks @Alain2131 : Sorry to tag you here, I just wanted some more help. Please let me know if tagging is not permitted or if you are bothered by it, I wont tag you again.
  5. I'm in the middle of creating Whitewater particles for my waterfall sim and after caching out the particles and converting it into a volume it looks extremely low res considering there is over 300,000 particles and 8 million Voxels. Not sure what i'm missing but any help would be greatly appreciated. Thanks in advanced.
  6. Hello, I have an object what I broke with an rbdmaterial fracture then I feed the points into a popnet and add some stuff like wind to move the points. My question is: How can I reset or rebuild or move back the points into their original place and shape like a fast rewind or something. Thank you
  7. Hello, I'm trying to create an effect very similar to the one in the reference video, where particles move through this channel and creep over this bubble. I tried different approaches like vellum grains, regular particles and came closest with the lava shelf tool. But then the individual particles are not touching the surface of the bubble and the overall movement of the particles looks too much like a fluid. I actually want the distance between the particles to stay constant. I think some PBD approach would work best, but can't quite figure it out. Any ideas? Thanks in advance. J NanoParticleEffect.mp4 190524_NanoParticles.hiplc
  8. Problems with two FLIP objects colliding

    So I'm in the middle of creating a waterfall scene which is going to flow down some geometry and collide with a lake. I've set up both the emitters for the waterfall and the wave tank for the lake in separate DOP networks. However when i try and bring the particles in from the waterfall into the lake DOP the particles don't seem to be having any interaction, the waterfall particles just fall though my static objects even though they should be colliding. Any help would be appreciated Thanks. Edit* I've noticed that the bounding box in the flip solver was not including the waterfall particles which fixes the problem of them not moving however the particles still do not interact with the wave tank. WaterFall_New.zip
  9. Hey guys! I've been searching around for this info but can't find it anywhere so maybe one of you wise owls can help. I'm trying to find a way to have particles shrink to nothing as the camera approaches them, has anyone got any idea on how I'd achieve this? Thanks in advance! Jeb
  10. Hey guys, I hope you're well. Just wondered if you guys had any idea how to drive particle scale by the brightness or luminance of a particle, so the brighter ones are larger? I've been messing around with Point Wrangle but my VEX skills aren't up to the challenge! Any thoughts would be appreciated, Jeb
  11. Curve attract Particles problem

    hey all, I have a curve, which is attract particles. Everything is fine, BUT the outer particles only fall down without a curveforce... SO I like to make a tornado with particles. but the outer particles fall down... how can I delete them or make attract to the curve?? and you can see in the screenshot that the inner particles a attract to the curve but the outer are fallin' down... tornado problem.hipnc
  12. maya particle

    I have one question but its from Maya I have three emitters & only one particle system. I have attached the particles to all the emitters so what I want is each emitter have its own different particle lifespan, so is it possible with expressions.
  13. Hi I'm trying to use the instance object to make different spheres on my different POP groups but whenever I assign the Instance to a specific group I get no result. Only works with no group specified. Surface Advect Final.hiplc
  14. stop motion with retime node

    i am sure i might be doing this wrong but can't see where it is, trying to use the retime node for a stop motion effect, on 3 or 6s?
  15. Hi all, I'm getting some unexpected behavior when I try to light my scene. I've got a particle sim, and I want those particles to illuminate the scene, so I assigned a Geometry Light to them. However, it's not acting as I expected. For one, cranking up the Intensity of the light does nothing. In the viewport, I can see the scene getting brighter, but in the render there is zero difference between an Intensity value of 1 vs 1000. Another odd behavior is that the light in the render seems to be dependent on where my display flag is set in the particle network, rather than the node that I told it to point to. I'll upload my hipfile to illustrate better, but basically I've got two null coming after my particle sim. One has a vop where I'm cranking the Cd way up, and the other is just the vanilla result of the particle sim. Even though I set my Geometry Light to point to the one with the overblown Cd, if I move my display flag to the other null then that is what gets used for the render. This illustrates the third strange behavior to me, which is that cranking up the Cd values makes my light brighter. Like the Cd is acting as the Intensity parameter, rather than the actual intensity. So in order to make my light actually illuminate objects, I have to completely overblow my Cd and ruin the color of my particle sim. Are these supposed to work this way? All three seem odd to me. If I've got something set up incorrectly though, please let me know. Thanks, -Chris particle_lights.hipnc
  16. I'm having problems in my scene trying to have dust particles and rigid body "stones" attracting to a moving point in world space. I have the stones set up so they attract to a point and collide with a sphere which seems to work just fine, however once i start introducing the particles to the DOP network the stones start to get influenced by the particles and start to gain a high velocity whenever a collision is made. Any thoughts on how to make the stones velocity not be effected by the particles while still having them collide. ParticleCollision.zip
  17. Hi, new to Houdini! What’s the best workflow to advect particles with fluid on a fast moving object?
  18. I'm attempting to create a polygon ribbons out of multiple streams of particles emitting from points moving around on a surface. I've been having a lot of trouble sectioning the streams into separate groups, so that I can use the add node to add polygons down the chain of particles. I'm not even sure if this is the best way to go about it. I'm using a popnet to create the points moving around the surface of a sphere, which I'm then plugging into another Popnet to emit the streams of particles. In the 'pop_trailsCreation' popnet, I have my emission type set to points. Does someone have a clue how I can create a polygon ribbon / tube moving down each separate stream of Particles? I've been trying to separate each stream based on the @id of each source_point, but I've had no luck in achieving that. Many thanks!!
  19. Attract/Morph particles to texture

    I have quite a simple question but haven't been able to figure it out yet. Using attribfrommap I have particles getting generated from a texture (e.g. circle). How can I attract/morph these particles to another texture (e.g. rectangle)? Thanks
  20. Hi guys, I managed to create a nice pop advection but no success so far on having a nice smooth look at the end. On this example, I just added a wispy smoke. Any idea on how I could achieve something similar? Thanks Isy
  21. Hi. I'm struggling to solve what should perhaps be an easy problem; - Release a fixed number of points with an animated point attribute, using POP's. Here's what I'm trying to do; - Take a packed object of fractured pieces. - Pass it to POP's. - Treat all objects as static as first. - Then release each object using POP's, using an animated point attribute. - Use transformpieces to animate the packed object. I'm able to do this with the RBD solver, but it takes an incredibly long time. I don't need the accurate collisions of RBD, but really need the speed of doing this with POP's. Below is a side-by-side scene showing the setup working if I animate the particles using @P, versus my setup that doesn't work because it relies on an animated attribute that doesn't get passed through to the points (because they are born on frame 1 and have fixed attributes). Help really appreciated! clinton release_particles_from_animated_value.hipnc
  22. Hello This is the most heavy project I've ever done by far. https://streamable.com/6hax5 If you have any comment or critique please go ahead !
  23. Hi friends, I've been searching for this for a while but have come up empty handed. Is there a way to create a collision detection (frame) attribute for flip fluids. I am currently developing a splash element that requires the colliding particles to emit smaller splashes upon collision similar to what you see in this clip. The kicker is, I am doing this without a tank and hence cannot use something along the lines of a crown splash. I plan on taking the frame the flip particles collide with a surface, and copy stamp instance geo to those points and then emit through another flip sim. It sounds complicated and it has become so as the element takes shape. I would attach a file but the project is under non disclosure. Any help would be greatly appreciated. Thanks in advance.
  24. Hi all, So I'm still new to Houdini and I have this project I'm working on to melt ice. I want it to look realistic and so I've decided to make it melt layer by layer (outwards in). I've scattered points on the object itself that act as melting points on the object however the result is not realistic and it doesn't melt the entire surface rather it goes through the object. I've attached an image showing a test with a sphere as the object to be melted, the white bits are the seeds that spread and activate the melting process(they spread through the object in a sphere manner rather than just spreading on the surface first then working their way inwards). So my question is, is there any way to group the outer layer of points of an object and make it keep updating so as the object transforms the outer layer will keep regrouping? OR is there any way to make the outside scattered points grow towards the center of the object (e.g. if I were to create a point in the center that attracts all the points surrounding it towards it)? Any feedback would be much appreciated Also apologies if I don't make any sense.
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