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Found 116 results

  1. 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!
  2. I am simulating a beer overflow and somehow I can't get all the particles to slide down the collision geometry, which creates artifacts when meshing the simulation. Friction is set to 0 for both the flip object and staticObject (not animated), stickOnCollision on the flipSolver/volumeMotion is off and I have also set collision detection to none under the flipSolver/ParticleMotion Any ideas of what to try? Thank you (All the blue particles on the side of the pint don't move much towards the end of the sim)
  3. Tank Gun Fire Dissipation Issue

    I want to achieve this kind of but my smoke is not dissipating quickly. and im getting stretchy smoke. i reduce the velocity to 0.1 still im getting that line shape smoke. sorry for bad english. i cant upload Hip file because of restriction. any suggestion should be helpful
  4. Hello; Is there any node that computes the Acceleration attribute (something like Trail SOP -> Compute Velocity)? Actually, in a particle simulation, I need that attribute. Thanks for helping.
  5. Stopping particles popnet

    Hello everyone! The guys need help how to slow down or stop a particle based on its age. That is, the more her age. the slower she moved and then stopped altogether deceleration.hip
  6. collide particle

    Hello, I have noob question. Is there a way to emit the geometry surrounded by the red line as collide particles? Thank you collide particle.hipnc
  7. i am working on the firework effect. i emitted some particle by pop locate and they replicate some particles when dead. Each original particle has orginal id and the id is inherited to replicated particles. What i want to do is assign the normal vector of Geometry( sphere) to the velocity of replicated particles and adjust them along the each original id. so i decided to iterate over original id with For loop inside popnet. I made array list of original id and each id inside the array is taken by Find attribute value count and again loop over with the count of point number that has each id on the array list. The point number that has certain id is bringing into the list called "plis" but the list is updating and deleting,adding new pointnumber. It is not accumulating. how can i fix this ? - my array isn't accumulating but adding one point number and updating the others repeatedly. and Do i complicate the process to make little bit simple effect ?
  8. Fipping particles 360 degrees

    Hi! I am a bit newbie, sry. I have to flip particles of a grid by 360 degrees, controlled by a null swiping through the grid. Here is my solution so far. Unfortunately I can not solve the 360 degree flip properly. It would be good to have some randomization of flip axis on it too. I wuld like to make some randomization on the scale too. Could you give me some hints on it , or perhaps edit my scene , please? Thanks in advance. Robert Flip particles on grid_10.hip
  9. Hi. I am currently working on an effect for tracer bullets on a fighter plane and I was wondering if there is any way to make the emission more controllable? Currently in my popnet I have 2 pop sources, one with probabilistic emission which creates a random emission pattern and one with it off so it emits particles at a constant speed. I have a switch setup so I can animate which emission method is used, but its either one or the other. I would like to be able to mix these 2 pop sources together so I could have a constant emission with added randomness created from the probabilistic source. ex: (20% of probabilistic, 80% constant or vice versa) Thanks hip file: machinegunfire_fx_ODforce_v012.hipnc
  10. Hi; I would like to add some velocity to particles from a volume (smoke), so I tried to use "POP Attribute from volume", but it doesn't work. How can I fix it? Actually, "POP advect from volume" works, but I would like to ADD/Multiply the velocity to particles, not advect them. Thanks for helping. POP_Attribute_from_Volume.hip
  11. A small fluid-related question

    Hi, Currently, I'm working on a small sim where a character gradually fills up with water. I'm trying to have more control over the emission rate, when using the emit particle fluid shelf tool. It seems like the "Scale Source Volume" slider on the Volume Source DOP has been removed. Normally, it would be found below the "Activation" slider. I attached a screenshot of the parameter view of said node. So, my question is as follows: where can I find a similar parameter in Houdini 18? Best regards
  12. Hi, I am importing an Alembic particle sequence from realflow. Shows up great in Houdini, no problems there. I want to 'mesh' it, I was thinking I would convert it to VDB and then to polys to have maximum control however the 'VDB from Particles' node is not taking the alembic particles (ie. nothing happens). Do I need to convert them to something else before? Am I approaching this completely wrong? Much obliged,
  13. guys , i got a big trouble, 1——let's say we have a model . the choose of model is important,models that are not rigorous enough will not expose the problem. generally 1)loop topology 2)parallel lines with changes in density(lines get close or far),like image below (there is a hip file i used attached below) 2——and now we want particles move along the direction like image below 3——that's it ----------------------------------------------------------------------------------------------------- what i have tried is using the 【calculated v attribute on model】 to make a velocity volume to advect particles or directly using 【the calculated v attribute on model】 to change the particle‘s v attribute continually , maybe plus minpos() locking in the end. but either failed , both make the particles have small inward deviation or outward deviation on velocity direction at every step/frame due to centrifugal force/inertia and finally make particles stick together. what i want to achieve is particles move along these directon and the motion/trail of particles don't have any shift/offset/deviation. all i tried just a very small part of the solutions, if you guys have any other great solution that can get the effect, please help ,it drives me crazy particles move along topology direction_TEST_MODEL.hip inward_deviation.mp4 inward deviation single.mp4
  14. Particle Sim Crashing

    I've tried caching out a particle sim multiple times each time it crashes at frame 190 of 240 and gives this error. Does anyone have any idea what this could be? crashLog.txt
  15. 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
  16. Hello! How to Increase Particle Separation for Spray - Setup whitewater solver?
  17. Hello; In a particle sim, I want each particle to fly to a goal point, but before reach to the goal, they should fly around (in a noisy path) like a bee. The problem is, they fly straight to the target (which I want to fly around), and after that, they don't stop! Thanks for helping. Particles_01.hip
  18. Hello , i have one issue with RBD Hero , it is possible to emit the same RBD hero object multiple times from particle or any objct without having to import the rbdobject node multiple times? Not packed prims only RBD Hero Object to have good floating objects on fluid tank. Becouse i try paked, prims and explode ater while, after few frames even when i play with feedback scale from Solver. Can you help me with a hit how i can manage this? Thanks.
  19. Magic Spell

    Hi guys, I'm glad to share the breakdown of my last project with you! This was my submission for a challenge hosted by Houdinimatic Community. Hope you enjoy!
  20. hi just learn houdini particle. i am a beginner in this project i use particles points then use copy to points node , boxs to make up model. like this picture however the problem is i find some box jitter very unacceptable so i Calculate the points distance between previous frame in solver node if the distance less than 0.05,then the point do not move this way make the points jitter less however i need calculate the angle distance between previous frame also but i do not know how to calculate the rotation difference let`s say ,if the rotation difference less then 0.1,then the point do not rotate. bellow is the project file point_jitter.hip thanks for your help
  21. Hello; In a particle sim, I would like particles to start to move (at a specified distance) toward an animated sphere and attach to its surface. I tried "POP Attract", "POP steer seek", "POP advect", without success! How can I achieve this particle behavior? Thanks for helping. Attractor_01.hip
  22. particles on a deforming surface

    How do I get the particles on the moving object's surface to move along the object's surface toward a point on that object?
  23. What should I do to allow particles on objects that are transformed and deformed together to follow the surface of the object to one point on the object?
  24. Hi Everybody! I have been following this amazing tutorial done by Vladislav Lavrenov. Everything works just fine but I'm trying to do some personal variants to this. I was trying to make the whole simulation collide with an object, in particular with a wall. I achieved in doing so but for some reason any geometry that gets put inside my popnet as a static obj gets taken by it as a new source of particle emission. Each point of the static obj is emitting particles or a piece of geometry of my voronoid fracture. I can't undestand how to via vex how to ignore the static obj geometry. Here in attachment are some screenshots of what happens... as you can see on the wall points there are particles that shouldn't be there. I guess everything is happening in my copy node and the voronoid geo gets copied in every point of the scene... but why, and how can I fix it? I'm really stuck and need somebody with more experience to help please. Here is also a copy of the project. Thanks in advance for the help!!!! Simone newexplosion_collision.hip
  25. Hi, So I've got a bunch of particles that die after 1 second. On these points I have geometry copied on it. The first second the geometry stays and the animation looks fine. But right after some particles start dying and are removed. The geometry jumps to other points and cause the animation to look weird and flickering. My guess is that if a geo is copied on pointnumber 1, and this point is deleted. Another point becomes number one and therefore the geometry jumps to that point. Both have a different id attribute. So I'd rather want the geometry being copied by @ID instead of the pointnumber. So that when that point dies the geometry is removed too. How can I do this? I've added an example file. Particle Copy example.hipnc Thanks in advance M Particle Copy example.hipnc
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