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Found 32 results

  1. 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
  2. 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
  3. Hello, guys. I am a newbie into Houdini, I am currently working on a personal project, the purpose is to acquire new skills throughout whole process. I was trying to copy a Circle Spline laid on ZX Plane, and base on its Scale Variation (Parameter set to Scale[1.05, 1.05, 1.05]), So copies will expand continuously on ZX Plane as Copy SOP total number increases. Then I wire into Popnet, trying to advect the Circle Splines by Pyro Sim. After Popnet I was trying to use Add SOP to connect all point and reestablishing its original look. (Tried both All Points and Group by Attribute) And it ended up wired looking connection, I even tried to use End SOP to close Polylines, but it doesn't work. Is anyone being kind to help me out? Thank you. I will attach screenshots and scene file. Stay Safe, Stay Healthy. Jaala Hsu PyroSim Advection.hipnc
  4. Hi forum! Seeking out some help here, cos I can't get my head around generating vellum geometry. I am working on a scene where I need to create close-up splashing water droplets on a static surface. Typically this would probably be a FLIP task but it seems like overkill and I am only after a couple of droplets, so the idea is to make rain and splashes with particles, copy some spheres on them and feed them to vellum to get some nice softbodies, then VDB them. My problem is I don't understand how I can "emit" on my source points that come to existence arbitrarily (ie. not on frame 1) and differentiate the newly created vellum patches. I've looked around, watched the masterclasses, I understand it has to be somehow parallel to constraint creation, maintain point count/id etc, but I cant figure out the solution. Its gonna be a single splash so continuous emission (as in a particle emitter per se) doesn't work for me. Any pointers are appreciated, check the hip for a rough sketch of the problem! Thanks in advance! od_vellum_splash.hip
  5. Particle workflow popnet

    Hi, So I was fiddeling with the popnet and finally got a nice stream of particles, but it doesnt render. It's in the viewport. But it does not render. What I have are several lines that are used for creating geometry. all these lines are in one geoSOP. I want to use the a single line as a source for popnets for my particles. Also for all other lines. So I created a subnet for this so it can be copied and paste. So everything in in one geosop. Now for some reason the particles only show up in my viewport, but the particles does not show up as spherers in the render. Therefore I made a little test and created an empty geosop on obj level with a popnet. This time the render does show the particles as spheres. So, what exactly is the right workflow for particle effects, so that I can render them. And what is wrong with my first approach. Hope you can help out. Thanks in advance, M
  6. 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?
  7. Birthing particles dynamically

    Hi All, I'm trying to get this setup working where I have particles that are being activated and turned on before being fed into a pop net. I'm stuck as to how i might be able to birth only each initial particle as they're activated into the popnet. I'm trying a couple of expressions in the impulse activations, but not having luck. I'm currently birthing particles at a constant rate every 5 frames, but what I would like to do is only birth once on each incoming particle. Any help would be appreciated as I'm still learning this Particle_Growth_example.hiplc
  8. particles around the mesh

    Hello Houdini guys! Can I Ask you for any advices in case of my issue? I would like to know how can I get same (or similar) result as down here in the scheme. (I am also attaching my simplyfied hip. file) I would like to force particles to the surface, but not let them just slide on that surface. Hope you understand what I mean. I will be very grateful for any advices. Thnak You guys. A: is how the script works now B: is how it should works issue.hipnc
  9. Vellum-popnet issue

    Hi houdini nation! Can I have any advice? Im trying to make animation of 5 testing geometries which are coliding between them selves. The position and rotation is defined by popnet, but when I connect it with vellumcloth, it doesnt use any animation data, even if I set Match animation in vellumCloth node. Can u help me pleas fix this issue? Thank u so much for any advices. issue.hip
  10. Hello houdini masters! I have small issue, in popnet. Im trying to create moving particles on plane, but with different "speed" U can see my intention on scheme down here. Can u guys please help me? I will be very grateful for any advices. Thank u very much!! particles_issue.hip
  11. what is a pscale attribute in houdini and how can we use it?
  12. Here is a small test setup I've made. It is advecting particles along a curve, driven by a velocity field. I added another velocity field pushing the particles back towards the centre of the curve and blended the two. This is done by deriving a new field, based on a volume gradient and multiplying the volume gradient by the volume sample and negating it. So far, I haven't tested it much, but it seems like it is working, but the settings will certainly need some tweaking. As in Houdini, there are very often multiple solutions to the same problem, I was wondering if there was a different way of achieving this...how would you do it or improve it? advectPush.hipnc

    Hello people, im trying to make a poly-line from series of points. Everything works perfect (picture_1) BUT every time when the simulation reaches frame 44 the lines close its rows, (picture_2) and I dont know why. Can U help me please fix this issue? Thanks a lot! ISSUE.hip
  14. Hi, In my popnet, I want that, a new particle is born only if there are no particles in the scene. That is, suppose a single particle is born and dies after, say some random frame, only then a new particle is born. No new particle can be born even if a single particle is alive. How can I do that? Please help Thanks @Alain2131 : Sorry to tag you here, I just wanted some more help. Please let me know if tagging is not permitted or if you are bothered by it, I wont tag you again.

    Hi, I'm Kind of new into this Houdini world and is not an easy world, but I like it, I got this problem: I want to make a fracture with debris, but I want that my debris wit its own geometry, So I searched, and what I understood was this: In the picture the null(out_dust) is the geometry that I want for my debris, and blast 3 is just the popnet but without a floor , when i watch the copy node is working but not correctly, the debris have the geometry that i want but the simulation is wrong, I made an example using poplocation and it works just fine, I don't know if the problem here is beacuse im working with a popsource, any kind of help will be really appreciated. ps: sorry for my english.
  16. Hello, I have a popnet with that emits one particle every 10 frames and I need to increase substeps to get more accurate result...however when I increase substeps it affects pop source and emits more particles. For example if I have 3 substeps, it will emit 3 particles instead of one. I've tried using gasintermittentsolve but when using that it just won't emit anything at all unless frames between solves is set to 1. Is there any other workaround for this? Thanks
  17. Hey everyone! I've been digging through the forum but quite haven't found something that will help me get this effect i'm trying to achieve. i'm trying to work on an setup where I have particles stuck on a deforming grid and the particles become unstuck as they inherit velocity in Y(sop solver) and then with gravity they come back down. my current setup might be too complicated because it's proving very difficult to control. i am using a popnet where particles stick to the collider geo and become unstuck with a sopsolver "if (@Cd.r > .1){ @stuck = 0; }" does anyone have ideas on how to simplify the setup? is this something that the grain solver would be better at handling? thanks everyone! waveRipple_v003.hip
  18. How to get the particle strike orientation to follow on from its initial shoot particle orientation. Have a look at the small attached files. tankStrike_v04.hipnc tankStrike4.mov
  19. POP force masking

    Hi everyone, I created few cubes and made each as a packed geometry. Now in Dop network, I am using rigid body solver for simulation, but as a force, I am using POP Force to drive them. But I need to select some cubes (packed objects) using bounding box and make them affected with POP FORCE. I used to do it with pop group, when using particles, but with rbd packed objects, it's not working. Please suggest a solution.
  20. Particle velocity diversion

    Hi, I have created a particle system using popnet.My emitter type is location. There is a sphere in the way of moving particles. I need to add a new velocity from the normals of sphere, to the existing velocity of particles. I tried using attribute transfer. It adds velocity, but only in data, visually particles don't seem to be changing velocity. They just go in a direction, as started from location emitter. Any solution would be helpful.
  21. Particles opacity control

    Hello, I have finished a particle simulation using popnet inside SOP in houdini 15. I have added color and opacity information using POP color node. While rendering using mantra renderer, the color is rendered fine, but as alpha, it doesn't render what I created using POPcolor. It's all visible/opaque 100%. I want to control opacity. I have not assigned any shader yet. Please share a solution. Thanks
  22. Hello there, I am learning Houdini and I tried to apply the GeoBoil setup to a dancing humanoid. I am struggling to understand how to use attributes to constrain particles to their birth position on the moving mesh. I have read plenty of related topics, but I honestly can't come close to any solution. I tried freezing the mesh with time-shift, scattering points, using scattered points to generate particles in the POPnet and then restoring the animation, but of course the particles remain in the position they were generated and do not stick to the surface. I attached the basic setup file and the .abc I used. Thanks in advance! boil.hip
  23. Smoke From POP

    Hi. Im new to smoke simulations and are no good at expressions. I have a simulation where I need to emitt smoke from particles. I want my smoke to burst/explode for just a minimum of time right after my particles dissapear/die. Like boiling bubles or something like that. Is there a good way to set up my smoke sim, so it starts from each particle in just at the end of my particles life and then make it explode? thanks for any help File to project: ToForums.hiplc
  24. 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
  25. 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!