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Found 80 results

  1. I'm currently following along with Rohan Dalvi's Motion Graphics tutorial, and I've run into two issues with the particles from the outer ring that I thought would have simple solutions, but so far have completely stumped me. The first thing I've found is that each point would spawn two particles, resulting in two lines very close together, and I want to get only one particle/line for each spawn. I've figured out the reason for this happen is that in my POP network I do two separate replicates, each on a different particle stream/group (so that I can have differing life lengths), and the replicate POP passes through the original particles (even those no being replicated) so after merging the replicates back together, I end up with two separate sets of the original spawner particles. Now the solution I came up with was to remove the points I didn't want to replicate, do the replicate for each group, then merge them back together (exactly like I would if I had this issue in SOPs). Problem is though that didn't work at all. I tried both Kill POPs and POP Wrangles, and a few different setups but nothing worked. I've included some notes with the scene file to give better explanations. Secondly, when the spawner particle collides with the tube, the replicator keeps replicating it, so we end up with a bunch of points stacked on top of each other, which I don't want. My idea to fix was to have a node placed straight after the replicate that removes any particles in the "hitparticle" group from the "stream_General_Spawner" group. That way, on the next frame, all the collided particles won't be replicate again. But this didn't entirely work either. "Combine Groups" on the Group POP almost did the trick, but in addition to removing the particles from the spawner group, it also removed them from the hitparticle group, which I don't want because I have a wrangle that does stuff with that group. Does anyone know why these issues exist? I'm guess that I'm missing some sort of foundational knowledge on how POPs work? Any recommendations for tutorials or articles to go along with the documentation to help with this? POPs_problem.hipnc
  2. 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
  3. Copy Debris Mesh to Pop

    Hey guys, Does anyone knows how can I copy these debris into the Pop Simulation points? (Scene file is attached) copy.fragments.to.particles.v1a.hiplc
  4. Basically, I'm creating a scatter points in a surface and I plug a POP Network, so I want that the Pop Network import those scatter points as particles, but I don't know how to do that. Can some help me to do it?. So I want to put the scatter points and use it as particles.
  5. Hi.I want to emitt particles from a boiling geometry(geo with spheres, at a random lifetime). But i need to activate emitting just as my “boiling sphere” is at the end of its lifetime. Im using two popnets, but no sure if thats nessesary.I cant to it with keyframes expressions it seems, because my boubles has random lifetimes.Anyone know how to controll emmiting with expressions based on pscale or lifetime?Let me know if i havent explained it good enough.This is sort of an extension to the https://vimeo.com/152083535 [vimeo.com] tutorial on boiling geo.thanks ToForums.hiplc
  6. Hi, I've tried it over and over. Suddenly the complete attributes are missing in the POP. I dont know the concrete circumstances when it happens. I think its different. Is it my fault, missing something, a bug? disintegration_v.2.hip
  7. Hi, I've tried it over and over. Suddenly the complete attributes are missing in the POP. I dont know the concrete circumstances when it happens. I think its different.
  8. Hi, I've tried it over and over. Suddenly the complete attributes are missing in the POP. I dont know the concrete circumstances when it happens. I think its different. disintegration_v.2.hip
  9. Hi everyone. Does anybody know how to use surface field in voppop or some dopvop to find the distance between my particles and surface. I want to make a force wind that depends on distance between surface and particles, so the farther point from the surface, the stronger the force of the wind. And the surface has really big waves for example, thats why i cant use just P.y for power of force for flat surface. Hope I explained it clearly)
  10. POP EMIT FEM

    Hey Guys, I am trying to get POPs to emit a finite element. I have a simple setup where I am birthing a particle every 50 frames and having this fed into DOPs where the finite element solver takes over. The problem is I cant seem to source more then 1 instance of the object into Dops. I have attached a scene file I hope someone can help. Thanks, Clive Balls_Test_Fem.hipnc
  11. I need to stick several million particles on their animated source geometry at the exact point where they are emitted from and follow the geometry's (emission point's) position. Please guide me towards any resource that might explain this process clearly. best regards
  12. Hi everyone, I'm trying to do a school of fish with a particle system that would follow a curve. Basically I'm emitting some particles and they move along a curve with a popcurveforce. By default the particles orientation seem to go along with the curve but since I'm trying to do a school of fish, I would like my particles Z orientation to always be 0 so the fishes don't swim on the back. So far I've tried with this expression in a popwrangle : p@orient.z = 0; The thing is it seems to zero out the orientation of x and y as well.. And I still want the x and y to go along with the curve. I'v tried with a popattract instead of a popcurveforce and I'm still not able to constraint the Z orient.. Maybe it has to do with something else than the @orient attribute since I don't see it in my geometry spreadsheet..? There's something I don't get! (Needless to say that I'm new in Houdini :P) Thanks a lot! test_fish_school.hiplc
  13. Popnet Kill

    Hello! I'm trying to kill points inside DOPs (well a popnet actually). The way I'd like to do this is by finding the closest point to the ground object (how do I reference an object in DOPs?) and computing the vector from the POP point to the nearest point, then dotting that onto the ground points normal vector. That's a nice way to figure out which side of the ground the point is on, then killing it. At least that works outside of DOPs. I'm wondering how I can do this inside DOPs because I don't want to post-process kill thousands of points if I can kill them in the simulation. Any ideas? Thanks, cw
  14. 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
  15. POP Fireworks - Color from Image

    Hey guys, I have to create fireworks that turn into some specific shapes. Just like this: I have an workflow idea working with colors. It goes like this: -Simulate standard the fireworks; -Go to a specific frame where the where the starbusrt* is fully formed; -Apply the color at this specific frame; -keep that specific color assigned to individual particles through the whole simulation; (not working) does it make sense? I'm having problems to achieve this last step. what I'm doing is: -caching the simulation; -apply the colors; -add a timeshif to the "rest" frame (89 in this case); -copy the color attributes from this frame (89) to the animated simulation; I guess it happens because the particle count changes during the sim. Any idea on how to proceed? (Scene file is attached) Thank you, Alvaro *starburst is the round shape Fireworks.v1b.rar
  16. Hello, I was wondering if it's possible to create velocity vectors from an animated sequence (texture). Ideally something similar to Optical Flow. I can extract movement from geometry (eg. use trail to generate v vector of animated VOP) and I can do basic image analysis (eg. convolution kernel operations on coloured points using VOP) so I feel it could be kind of possible to do it but can't get my head around it. In terms of results I'd like to create a particle system that reacts to an animated texture (eg. overlay particles on a animated texture and have them follow the movements in the video) thanks!
  17. sand disintegration

    Hello, I'm trying to get a logo to dissolve/disintegrate into sand. Like it is made out of sand and something is eating out the outside shell and the sand is pouring out. In the attached file I was first trying to use a geometry and use attribute transfer to set the force of a popforce. as I would like to use in the future a more random/noisy pattern. I'm not exactly sure if my expression is wrong, if my whole set up is wrong. I tried to look around for tutorials or thread but couldn't find any. Any idea, suggestion or links would be greatly appreciated. thanks bil Sand_Desintegration01.hipnc
  18. Use Points as Particles

    Hi, Let's say I have a bunch of points that I have created, and I want to treat them as particles in a popnet - how do I do this? Is it possible to do this without emitting from the source points for one frame? I noticed that you can set the initial geometry for the popobject node, and gravity and forces do effect these points, but no pop nodes do anything at all. How do I get the pop solver to consider these points as particles? I have attached a simple example. (Note: The popsource node has the Geometry Source set to 'Use DOP Objects', but this is undocumented) Points_as_Particles.hipnc
  19. Hi does anyone know how can I add a hard constraint between two or more particles ? exactly like RBD objects but it should be work for POP solver. I prefer do this via custom VEX codes for manipulating P or V. Thanks S
  20. Hi guys, I've hit a bit of a wall in the new version of POPs. I have a deforming mesh (skinned character), which I have scattered points on. What I'm trying to achieve is a set of particles that are essentially locked onto their source point until a certain time or proximity from some sort of gizmo, and then morph to the position of another set of points. I have been able to achieve this in the old version of POPs using a position node, but it's rather slow. However I can't seem to figure out how to achieve the same thing in the DOP version of POPS. Any help would be great appreciated. Thanks
  21. Hello, everyone A simple question, it's basically the title. By "increase" I mean increase by a lot. Everything the same, just turning on "Use deforming geometry" increases the sim from 60 frames in around 8 hours to 7 frames in the same time From what I could see it really takes a long time in the "creating collision mask" (or something of the sort) step. I have the VDB of the colliding object already cached in a SSD. So, is this normal? Also, a side-question, when you use a static object in DOPs, does it use the Bullet Solver or the RBD solver by default? I'm sure I saw this question here before, but unfortunately I can't find it
  22. retarget or recompute vector

    Hi everyone, I try to figure out how to retarget a vector (v in that case) in particle trails. I explain: i got master particles who trail other particles in space, i inherit the master "v" to achieve a motion blur at render time, to avoid to much substep that way i got smooth line at low calculation cost. but i need to slightly noise the trails to achieve a "moving tentacles" look. Here is the problem when i apply the noise, obviously my "fake" v vector is not aligned anymore, it's stepped... i tried to recompute the vector with the help of id, but since my emission is not constant ( i shot on frame 5, frame10, frame15 etc..)the incrementation of the id in not constant to...I tried basic vector arithmetic, but i don't get results i need...I join a hip file, does anyone got an idea??? thanks by advance. Best H PS:excuse my english, I'm French... RecomputVelTest.hip
  23. Hi, I create a new project but have a new problem. use to source object its has not problem but when added the point on source objects its changing rotation. I hope, you can help me for ı can fix my files.
  24. 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
  25. Pops following animated mesh

    Hello everyone ! Does someone know how to use an animated mesh for driving some velocities of particles ? I have done a sim that I like but I want it to follow the character's animation... The particles born in the chest and goes to his head which is rotating... I'm pretty new to pops, I think that maybe I can make it move through a pcopen but maybe it is a bit too much for what I want to do ? Also, I'm not pretty sure about how to make it... Maybe it's possible to feed the pcopen with a scatter of point on the surface of the character ? Thanks a lot and have a great day ! (Once finished and online I will try to post it as a comment !)
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