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Found 67 results

  1. 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
  2. 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?
  3. 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
  4. 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.
  5. 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!
  6. 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
  7. 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!
  8. 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
  9. 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
  10. 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
  11. 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.
  12. 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!
  13. 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!!!!
  14. 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
  15. 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
  16. 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.
  17. 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
  18. Hi guys! Suppose I have a sphere filled with particles, and there is a growth map on it. I am activating the particles based on this growth map and a wind force blows the active particles away. I am only emitting on the first frame. copying the growth map attrbs via sop solver. If my wind force is too high it will cause gaps in between the particles as they are pulled away. Will dop/pop substeps work properly and fill the gaps when there is no emission happening? The growth map has in between frames, I've put a time blend sop to be sure. But I am having a tough time getting the substeps to work Would be great if anyone has any suggestions. Thanks!
  19. Hi all, I'm building a crude crowd-like system using POPs and I'd like to copy my imported walkcycle on to the particles with a random timeoffset. The old method of copystamp with a timeoffset value on a timeshift node works - but it's really slow. I've been reading up on the for-each / compile block method but I'm unable to compile timeshift or file nodes. So my question is - is it possible to do it with a for-each/compile setup or am I stuck with the old copystamp method?
  20. Hi guys, I’m trying to get POP object and a FEM object to have two-way interaction. The pops are colliding with the FEM, but the FEM object is not being affected by the impact of the POPs. What do people think is the best way to get this to work? Currently I’m playing around using a SOP solver on the finite FEM object to bring in “feedbacks” input. This seems to contain a the particles that hit with fininte element. The pt’s have hit attributes and, “impulse” and a normalised “normal” attribute which I assume is direction. Not sure the best way to apply these feedback points to the finite element. Which attr should I modify and what do we think is the best way to lookup the "feedback" data? Perhaps a point cloud lookup? And suggestions greatly appreciated!
  21. POP Grains Collision Issue

    Hey there, I'm having an issue with my POP grains sim. I'm trying to simulate spaghetti or noodles on a plate which are thrown up into the air as the plate is flipped. I was able to modify a scene file to create the noodles and create collision geometry based off an alembic file I was provided. However I'm having two issues: 1. My grains don't stick to the plate the entire time, some of them go through my collision geo 2. I'm getting some very weird stretching with the grains as the sim progresses. I'm not sure if there is some other collision elements that I am missing or settings on the grain nodes that I need to tweak. I've attached a flip and hip file. Any advice would be greatly appreciated. Thanks! noodles_v01.mp4 noodles_v04.zip
  22. Hey all, I'm banging my head against my desk trying to figure this out....I'm attempting at creating a spaghetti-like simulation where noodles start out on a plate, and then the plate is flipped and throws the spaghetti off the plate. I'm generating some noodle-esque lines using pops and grains but I cannot for the life of me figure out how to get them to not intersect. Am I missing something? I was also hoping to add meatballs to this at some point as well which would be sitting on top of the noodles and then get thrown off the plate as well....would this be accomplished with adding a multi solver to my pop network that combines the popsolver with a bulletsolver? I've heard grains and RBD objects don't play super well together so I'm not sure which is the best approach for something of that nature. Thanks for your time!spaghetti_RD.hipspaghetti_RD.hip
  23. More Particles Following a PATH!

    Hi Guys, I have a system of Pops where particles are following several splines with a PopCurve Force node. I got everything working the way I want except for one small detail that I have not been able to figure out. The detail is how do I align the particles so that they face the direction of the spline? I don't want them to bank along the spline per se but just have an axis aligned to the spline almost like dominos or people marching in a single line along the path of the spline. It has to feel very organic which is why I am using POPs with forces and things like that as opposed to doing it in SOPs. I thought maybe a POP LookAt would work but I am not sure how to get the curve alignment data to POPs. I am sure this has been done twelve ways from Sunday but I am pretty new to Houdini and haven't able to figure it out fully as of yet. Anything advice on this would be awesome. Thanks! Cheers, Christian
  24. I am trying to get some temperature data that I have calculated on the output of a particle simulation to make it work with the pyro shader, but I can't seem to get it to transfer. I am using Volume Rasterize Points to get the particles into being a volume, which is working really well, but I can't seem to get anything but the density field filled. The node supposedly takes point attributes and fills a volume field with the data if it exists as both a field and a point attribute, which these do, but I keep coming up with empty fields. Failing that, I tried to brute force them over using Volume from Attribute, which I had successfully used elsewhere in the scene, but to no avail. Still giving me empty fields. This has started to become quite vexing, as I think it should be working how I have it setup, and it isn't. particleTest1.hip
  25. I am trying to do a sort of Sci-Fi explosion, still deciding on the story behind it, but I know the look I am going for. I want to have an energy core going critical with energy masses spinning around it as if following magnetic field lines. I finally got my field lines working right and got them into a vel field, but now I can't figure out how to cause it to animate the particles. I plan to generally control the animation from this velocity field, so it is really important that I actually get it working. Any suggestions? I have attached the R&D file I am working with so you can see where I am with all of it. particleTest1.hip
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