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Found 75 results

  1. I'm currently building a POP network to simulate rain on a window and would like to mimick the small variations in surface tension that help cause the erratic motion of rain drops running down the surface. I know how to do vary an attribute using VEX, but I'm not sure how to go about it with parameters, since I can only assign one friction value for the whole of the geometry in the Static Object SOP. Any help would be great!
  2. Greetings! I'm trying to attach a vellum sim to a pop sim... The idea is that I first do a pop advection sim then attach vellum cloth to that so they collide and interact with each other... It's almost there, with one slight issue. It seems that vellum is calculating the particle point for every frame and I need it to calculate only the newer emitted (birthed) points... Is there a way to tell it to do so or is there a cleaner setup to achieve what I want? Attached is a simple test scene of where I'm at. Any help, guidance, or advice would be greatly appreciated! vellumParticleTest01.hiplc THANKS
  3. Houdinified Acrylic Paintings

    Hey peoples! I recently started a personal project with the main purpose to explore setups that I either couldn't do during real production, curiosity or pure fun. As a base and also source of inspiration I'm taking real acrylic artworks of a good friend of mine. The photographs of the real artworks are prepped in Photoshop to be able to extract certain textures which I then use in Houdini to create my setups with. The concrete room was built out of a couple of individual decals and assets from Quixel. The whole thing is then being rendered with Redshift, comped with Natron and finalized in Davinci Resolve. From time to time it's seriously fun to play around with setups without having somebody behind me telling me what to do creatively like in a professional environment. No pressure, just fun Here's the first couple of clips I created in this series. Hopefully it's as fun to watch for you as it was creating it for me! You can also check it out on Instagram, Behance or Vimeo. Feedback, questions or whatever appreciated! Volume 1: Volume 2: Volume 3: Cheers!
  4. Wispy Magic FX

    Hi everyone, I am trying to achieve a wispy magic Effect like in the attached example. I have tried emitting Particles from circles and lines, advecting them through velocity fields from pyrosims and different noises, but im not even getting close. I just can't get the stringyness right. Can anyone point me into the right direction? Regards, Dani
  5. Hello! I've been using Houdini as a TD for about 2 years now and I just recently got my hands on a C4D and X-Particles license. Playing around with X-Particles it has become apparent that Houdini can make something fairly simple (like particle simulations with constraints) very difficult. For these past 2 years I've been trying to get, specifically, thick liquid like particle constraints (not just viscous but stringy) working in Houdini and I've never been able to get results I can be completely happy with. I've been able to achieve "sticky" effects using vellum grains and vdb meshing before as seen here, however, I was always after a different effect using a particle simulation that was NOT attached to a mesh but still behaved in a similar "sticky" fashion when coming in contact with colliders. After trying this over and over again in Houdini and having unsatisfactory results, I've now experimented with X-Particles and I was a slightly frustrated by all of the time I had spent in Houdini and how simple and quick it was to achieve exactly the effect I wanted in X-Particles. In the video below you can see what effect I was after in XP. I was curious if anyone at all has re-created this stringy liquid effect in Houdini with POPs? It seems clear to me that FLIP fluids are not really the answer for small scale simulations where you want a "stringy" surface tension look. I've gotten close with FLIP and vdb meshing in Houdini, but it never looks as natural and real as X-Particles. I've heard that maybe the POP Fluid node may be the answer (here), but I'm curious if anyone has attempted these stringy constraints in a Houdini project! Any Houdini workflow tips for such an effect would be appreciated because the cost of X-Particles and C4D is not something I plan on paying for the rest of my days!
  6. Hi everyone. I have a very basic setup and a problem that can't solve. I cant transfer "density" attribute from volume to particles using POP ATTRIBUTE FROM VOLUME. But I can't transfer color, though it should work in a same way as density attribute transfer. I include here printscreeens so you can see easily. I create te volume, assign color with color SOP. Refer to this color sop within POP ATTRIBUTE FROM VOLUME, refer to Cd as a name of a volume and.... nothink works(. Thank you in a advance.
  7. POP Drag expression error

    Did I do something wrong here? Getting a "Read only expression on left side of assignment" error... could someone help me solve it.
  8. I have a popforce node which I would like to fade amplitude from a value to zero over time. The expression below eases in using age. amp *= smooth(0, 1.5, @age); How can I ease out?
  9. Fire Sparks from Pyro Simulation

    Hi there! I'm trying to figure out how to create a POP emitter from Pyro in order to have a realistic (and procedural) Fire Sparks simulation based on heat amount. I've tried something but it's a very rudimentary solution, especially because I'd love to emit particles from top of fire (maybe when heat field falls down). How I can use a pyro field as POP emitter? And, most important, what field do I need to use? Do you have any suggestions, tips or tuts to share with me? Any help will be really appreciate! Thank you for your time. mois_fire_sparkles.hip
  10. Hello Houdini Magicians, This little bit of code is, according to the performance monitor and some debugging, slowing down my simulation... alot. Specially with a high number of particles. The nPt comes from the nearpoint function. I analyzed the performance impact of the nearpoint function with many particles and it is not significant. Its the conditions and moving/removing particles from groups. What is the optimal way to do this?
  11. Photoreal Honeycomb help needed

    Hey ya'll, So I've been working on this photoreal honeycomb for a project and I'm not happy with the amount of detail I'm achieving. I'm relatively new to Houdini and I've been trying to use it as a Generalist package however as soon as I have to use any code I start to feel out of my depth. In saying that, my current solution is almost all procedural and all with nodes and no scripting. I have opted for using attribute noises and point VOPs to generate roughness, displacement/surface noise as well as using shader displacement/normal noise to get High frequency noise without having an insanely heavy mesh. I should mentioned I am using redshift to render currently. So my main question is how can I make this look more detailed and more photoreal? (I have provided a render of a test section as well as photo reference of the detail level I would like to achieve.) That test render is the starting point of a camera animation, so that is as close as I intend to get to the honeycomb. I was wondering if I should use a solver to get an organic growth effect or maybe a volume vop? I have tested a volume VOP set up with no luck. Also I find my shader in redshift gives me a plastic look with too much sheen and the normal/displacement looks fake but I can't get it looking better. Any suggestions would be greatly appreciated as I feel I've reached the edge of my knowledge on this. As mentioned I am currently using Redshift, however if someone has a Mantra solution that works well I would be happy to look at that too. I have provided a hip file with the dome light HDR and the mesh cache as well for simplicity. Annnnd this is a small section of the actual amount of honeycomb needed, the actual size is probably 10x that section. Thanks in advance for your help! Jon beach_parking_8k.hdr Honey_high_res.bgeo.sc JW_Honeycomb_Detail.hip
  12. Controlling FLIP Emission

    Hello, I'm just experimenting with FLIP fluids for the first time and was wondering- is there any way to prevent the initial "glob" of liquid that emits on the first frame? Ideally I'd like the emission to start at nothing and then gradually build into a thicker stream. When I uncheck "Create Particles" in the FLIP Source node it removes the particles from the node, but has no effect on the sim.
  13. Emit Time Range till End Point

    Hey Guys, i got a question. I got a vellum sim and i am emitting every 8th Frame one sphere into my sim. I did it with -> $FF % 8 == 1 but now i want that emission just between Frame 1 - Frame 48. So between F1 and F48 i want every 8th Frame an emission. How can i get this with an expression? Cheers and Thanks!
  14. Packed RBD from Pop Sim

    Happy Friday, Trying to wrap my head around constraining or copying packed rbd's to particles that are moving along a surface. Attached is my test scene please help if you have time! Thanks, particleRbdTest_01.hip
  15. Hi, I have an issue that I have not been able to figure out. I need particles/fluid to follow a curve, which I know how to do easily, but this particular curve crosses over itself a couple times so using Volume Velocity and Curve Force causes to particles to divert off by grabbing on to a later section of the curve. (ref images attached) Is there a way to restrict them to the current section they are on so that they ignore the areas where the curve crosses over itself? I have not been able to figure out a way to do it so I thought maybe the amazing Houdini brains on here might have an idea? Thank you in advance for any help/suggestions you can offer!
  16. 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
  17. 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
  18. 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
  19. Hi, Does anyone know how to create variable friction for collision geometry when using particles In houdini. In maya or realflow you can create/paint friction maps. I was wondering what the houdini workflow is to create this. Thanks in advance, R.
  20. How to Transfer UVs to Vellum Grains

    Hey, has anyone tried this yet? In the past when creating FLIPs I would normally carry UVs through DOPs using an attribute promote to carry the UVs from vertices to points, but it seems like this is not working when applying the same methodology with vellum? Please help!
  21. Hi Everyone I am trying to replicate the output of this tutorial in houdini which was done in 3ds Max by Allan Mckay i am trying this thing in houdini since weeks but i am no way near to that......... A little help would be appreaciated!!!!
  22. Hi, I am trying to create condensation or water dripping over the surface, something like this, but so far i am totally unsuccessful. A liittle help would be appreciated
  23. Stylised Trails

    Hi Guys, I need a little advice. I am trying to create trails that have a look similar to the image below. My initial thought was to scatter points on a circle with an initial velocity and then advect them through a volume using curl noise...before using an add sop to group by id (Hip file attached). I am having difficulty trying to replicate the look and feel of the trail animation in the video below at 0.24. The trails appear very wispy and almost fluid like. If someone can help point me in the right direction that would be greatly appreciated. Many thanks, Clive Test_Curves.hip
  24. I've been stuck on this for a couple of days now and would love to hear you guys' input. I have close up shot were a character's feet is pushing through snow up to his ankles. I decided to try grains for this (it's my first time really using it) and to get the snow together I used the constraints set outside in the grain source. Mostly the sim is working as intended but I'm getting a lot of unwanted fast movement from some particles (as if they're trying to keep the constraint but not really keeping it, so they pop in and out, and that results on a flickering on the meshing. Did anyone come around this problem before? I am up for any solution at this point, even trying another method.
  25. Random pop bounce direction

    Hi, I'm trying to achieve a simple effect, but am struggling to get my head around it. I'm sure I'm overthinking it but if anyone could help me that would be great! I'm trying to get a random bounce direction on particles when the collide with the ground plane. As if the particles were small stones bouncing randomly due to a bumpy road surface. I've attached a hip file with the basic setup. I was thinking maybe you could inherit a random vector as the collision happens, but couldn't seem to figure a way to do it. I know various sources have mentioned the old "gain normal" parameter, but this no longer exists. Any help would be much appreciated. odforce_randompopdirection.hip
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