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Found 206 results

  1. Hey everyone! This is my first post here! I have a scene where I'm caching a vellum grains simulation to a disk cache. I'm having trouble understanding why it takes so long. When I cache the simulation to ram in the viewport each frame takes about 15 seconds, however when I drop a File Cache SOP and save it to my hard drive each frame seems to take about 3 minutes. Could someone explain why this may be? I have tried saving to another drive and it didn't help.
  2. I'm currently working on a POP netowork to simulate raindrops on a window, and am trying to isolate the original particles from which the trails (in red) are emitted as per an emit attribute using the POP replicate node, so that I can selecting apply a POP interact force to them. However, I'm really struggling to find a way to isolate those points. I couldnt find any reference to the original points within the POP replicate node, apart from the fact that their ID is added to the sourceptnum attribute. Am I missing an obvious solution? Thanks
  3. Instance node loses UVs

    I have an animated alembic loop that I am copying to points from a POPnet, but I want each copy to be slightly randomly offset time-wise. I would love to be able to do this with my original alembic (I'll be posting this question separately), but the only method I've found is Tim van Helsdingen's method that explicitly calls the cached frames, just adds an offset to the $F part of the path, and then uses the instance node to do the instancing, so I'm doing that having recached my .abc as a .bgeo sequence. The problem is that the instance node doesn't retrieve the UVs for the objects, and I haven't been able to find a way to get them to carry through. How can I get the UVs to be seen in the instanced objects? [ADDENDUM: I figured out how to do it using a for-loop for all of the emitted points, copying an instance of the .abc going through a time shift that randomized a frame offset based on the iteration count of the loop. This works, but is also considerably slower for the merely-300 objects I'm instancing, so any alternate-method suggestions are definitely welcome!]
  4. Hi all. This should be easy, but it's killing me... I have a control object living outside a DOP network, a simple particle system. I've plugged it into the second input. Inside the DOP I access this control position without issue, in a VOP. However I then want to follow up by killing particles in a POP wrangle, based on distance to the control object... Easy right? Here's my vex: f@dist = distance(@P, v@opinput0_P); if ( @dist <= ch("threshold")) { removepoint(0,@ptnum);} ... simple. But it kills particles around the origin, not the control object, as if v@opinput0_P = {0,0,0} I've tried multiple variants on opinput, explicit path and the point function etc but it always gives me a "kill" radius around the origin, not the control object. Anyone see what I'm missing? Thanks in advance!
  5. Houdini.School Velocity Forces

    I am happy to announce that https://www.houdini.school has launched and you can get 15% off now through July 27th, 2021. I'll be joining a host of talented Houdini teachers, like: Debra Isaac Kate Xagoraris Beck Selmes Christopher Rutledge Justin Dykhouse Jeffy Mathew Philip Nicholas Ralabate You can learn more about my Velocity Forces class here: https://bit.ly/houdinivelocityforces Teaser video for my Velocity Forces live class: https://vimeo.com/577928177
  6. Hello! This is my first time posting here. I am a graduate student currently working on a project that involves a character comprised of rigid objects that can assemble, disassemble, and rearrange itself. The parts can also blend between dynamic and keyframed states. I have a method for the state switching, but I cannot seem to find away to apply any attractive or guiding forces to the parts when they are in their dynamic state. I found a way to do this previously by using a POP Attract node, but it only worked with Rigid Body Solver. I'm not sure how to apply that same node to a RBD Solver. If any knows how to make that work or knows a better method, I'd appreciate it. The goal in this test is to make the ball roll towards the cube and fit into one of the sockets. I have attached a zip file with the assets and .hip file. Thanks in advanced! RBDTesting.zip
  7. Flickering Liquid

    Hi there! I have this melting setup with a POP solver, basically scattering some points onto the original mesh and then melting then and meshing back everything again using "particlefluidsurface". So I have been trying to get rid of this flickering on the mesh, I have over 500k points and I also tried increasing the samples and playing with the particle separation in the "particlefluidsurface" I also tried using "vdbfromparticles" but its more or less the same result. I want to know if there is anything I can do to help reduce the flickering? Any help on this is much appreciated Thanks in advance untitled10.mp4
  8. I am trying to get donut sprinkle fx. like someone is dropping sprinkles to the donut for toppings. but i am not able to get it right. attached hip file is a basic POP sim setup, part i need help is when the particle stick to the geo/collider/donut the sprinkles are standing up. what i want is to randomly placed or stick on the geo. like the pic. POP_Sprinkle_Odforce1.hiplc
  9. Mulitple Pop source emitters

    i have around 100 points that are emitting particles. each source point in SOPs has an attribute i would like to use in DOPs to activate or deactivate the birth of particles. i cant use it directly in impulse activation unfortunately How can i do this?
  10. Rbd objects emit particles

    i have some cubes that fall to the ground. I am trying to emit particles at the same time from the front side of each cube creating noodles that collide with the cubes. i thought the multisolver might come in handy but its not working so far. First time i am using it. Essentially i am trying to replicate grain emitted noodles on cgwiki https://www.tokeru.com/cgwiki/index.php?title=HoudiniDops#Grain_emitted_noodles but my source is an rbd object. i am not sure if this is possible. test.hip
  11. POP proximity to group

    Hi everyone! I have a very basic POP setup. The side with positive P.x belongs to group "right". With a "POP proximity" node I check nearest particle. My goal is to fins if particles from "left" have a nearest neighbour from group "right" and if they have color them red. In my opinion it should be simple. The nearest attribute gives you a number of a nearest point and you use it within "inpointgroup" to check if nearest belongs to this group. If it belongs color red the point that has a current nearest as its attribute.... But it doesn't work. I tried to put the same code in in a "geowrangle" but it wasn't working also there. (in general what's the difference between "popwrangle" and "geowrangle"???). I trief to solve the problem avoiding "inpointgroup" by assigning the attribute ntest to particles from the right and checking in popwrangle within "point(0,"ntest",npt)" if a nearest has the ntest attribute equal 1... but again things aren't working... Apparently "point" doesn't work that way in POPs or I use ot wrong... don't know..
  12. pop fluid along curve problems

    Hi all, I have pop fluid running along a curve. All great at the start but when it gets near the end of the curve, the fluid floats away, gets a little messy. Any advice on keeping the particles on the curve? hip file attached. waterSpiral.v011.hip flipbook_waterSpiral_v10_waterSpiral_v10.mov
  13. POP stream/group in wrangle

    Hi everyone. I have a pop stream called "stream_main" and is written that its a pointgroup. Though when I refer to it in a wrangle, if doesn't work. I don't know why.
  14. POP Force Mass Remap

    Hello Everyone I noticed that many parameters have a "Use VEXpressions" checkbox and i try to understand them. In my example i would like to remap the mass of the pieces by VEX. Preferably using a Ramp! And all that inside the local VEX of the POP Force :-) So that there is a better distribution of pieces in Y. I can't make it work... should it?
  15. In a pipeline that requires you to do VFX work in Houdini and then render said VFX in 3ds max, there are many formats that are viable (I mostly use alembic). But I was not lucky finding a straightforward method/format to export particle systems that were created in Houdini to be later replaced by geometry in 3ds max for rendering. After some tests, we managed to do it using an HDA called PRTRop which exports particles in .prt file format. The particles were then imported into 3ds max using TyFlow, that reads a couple attributes such as width (pscale), id - this one is necessary for tyflow to import the particles, velocity, etc... Then we hit another roadblock: what if I want to export particles with orientation information for my geometry instancing? It turns out that, after some more testing, we discovered Tyflow uses an attribute called Orientation (case sensitive) which is a quaternion just like Houdinis orient attribute, and it has to be exported as a float16. So in case some of you were wondering how to do this, I'm sharing the workflow used here. If some of you know a better way feel free to share it... it might save some lives! Cheers, Mozzo
  16. Object pop collision

    Hi I'm working on a test with arrows soothing on object, a very basic copy to point with particles Right after the arrows emit the object they are not falling not in a natural way they are "standing" attaching image and the scene, hoping for some help in this thank you Arrows_Test_01.hipnc
  17. Hi, I'm quiet new in this big world of Houdini, i need help. The project consists of creating spheres on the points extracted from a pop simulation and then destroying them. The problem I encounter is that when I put the glue on different spheres it seems that it creates the glue on all the broken pieces. It could be the fact that in the assemble node, it considers those points as a single geometry, but I don't know how to divide those points as unique entities and then apply the glue only on the individual spheres and not on all of them as a single object. Thank you in advance for your attention and any help. I attach the file below. Thanks a lot! Fra_pop_copysphere_and_rbd_.hipnc
  18. Hello everyone! I recently made a setup to achieve magical smoke effect that orbits while moving. I shaped and animated a bunch of points that move along a custom curve. I want to make all those points orbit or twist around the original path (curve), something similar to curve force node for POP. I'm having some difficulties making this happen with VEX. I would appreciate your help. Cheers; Basic Shape.hip
  19. POP wrangle number of inputs

    Is there any way to add more input slots in a POP Wrangle node? By default it has 4.
  20. POP particle collision/final resting

    OK... I think I've exhausted my button pushes and research. If anyone can give any pointers about getting my collisions/debris to actually appear to rest on the surface and/or interact with the moving model I would be very thankful. Currently, the `debris` appears to come to a final rest above the surface. I've included the scene and ref'd geo. quinniusMaximus_recog.zip
  21. Hi. During Rigid Body simulation. Is there a way to scale up particles at first, And then scale down and delete at last. kind regards. popdopchramp.hip
  22. Hi there, I'm trying to learn vex, but I've run into a bit of trouble with the RBD solver. My goal is to apply forces to individual points on a model, and have the model respond appropriately. My first assumption is that I would use a bulletRBD solver to accomplish this, along with a POPForce node. However, this applies force to the center of mass of the object, which is fine, but I also want some rotational values as well. For instance, if I have a cube, and I apply force (0, 10, 0) to verts on the left side of the cube, and I apply the opposite force (0, -10, 0) to verts on the right side of the cube, I would like to see the cube spin. I know I can manually edit the @w attribute to add angular velocity, but do I have to calculate the angular velocity manually to make this work? Thanks for your help.
  23. Deform Box of Points (cells)

    Hello friendly helpers, to make it short and maybe a bit more easy to understand what my question is - a few screenshots. I tried it self coded which works well with a grid. Deforming a box works fine with a ripple solver. When i put a box into the sin-wave wrangle - the box deforms completely to the x-achsis... I want to have a box of spheres, which behave like a sin wave over the whole box. The farest where i get my head is to have the spheres sitting on the x-achsis. But i need them as a box of spheres. It would also be nice if the spheres would collide between each other. I thought of doing this with vellum grains which worked actually pretty well, but in the end i got problems with forces. Is there any way to do this with vector force or velocity volumes? Or has my code the potential to fix it fast? ^^ Have a wonderful sunday btw
  24. POP Sourcing into specific DOP object

    Hello, I have two different DOP Objects (RBD Packed) and I want to source Geometry into just one of the objects, not both. I am using the popsource node which by default sources to both of my objects. (Using just one object is not an option for now) Any tips? Thanks!
  25. Rhythmic particle emission

    Hey everyone, this seems like a rather trivial thing, however, I'm a bit stuck. I'm currently working on an AA gun-asset to create tracer fire for a couple of night shots, but I'm having trouble getting the pop source to emit a constant stream of particles. It works if I set the emission to once every frame or once per substep, but for all other combinations of timings I tried, I get a stuttered particle stream with lumps and gaps. I must be missing something here. Surely there is a way to quantize the particle emission to be more regular? Thanks in advance! aa_asset_dev_v001.hip
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