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Found 18 results

  1. I am doing a small rain system. When i add the trail sop, followed by an add to connect the point with the ID attribute, everything works fine until i set the trail increment to a value different than 1, then it completely breaks. I believe it is because particle are dying, but i cannot figure out how to debug it Trail_sop_issue.hip
  2. Hi, I've object merge in my rbd sim and passing it through a trail sop to compute the velocity.The trail sop seems to be computing velocity before anything is moving in my sim,and the velocities are all over the place? Thanks a lot Josh
  3. Hi everyone, I've run into an issue and I'm looking for some help coming up with a work around. We've got a lot of effects that involve smoke trails from characters flying around and we've been using pyro clustering to make the trails. However there is one particular issue I just can't think of a solution to. The default cluster setup transfers the cluster number to a trailed collection of your source points and then finds the lowest source frame in each cluster in order to determine which frame each cluster container should be created on. This works fine normally, however if your trail loops back on itself or comes too close to where it was in world space at another point in the shot then the cluster gets confused as to which container should be used resulting in gaps in your trail. I've been trying to come up with a way to fix this procedurally but keep hitting dead ends. has anyone run into this issue before? Short of trying to convince animators to never have the characters loop back like this does anyone have any ideas on how to circumvent this problem? Thanks in advance, -Brandon
  4. Plane Smoke Trail

    Hey guys, Trying to do a smoke trail simulation similar of a jet stream. I've attached a sample hip file below of my current setup. My plane is static and the camera is animated. I've isolated the engines and use it to do a particle simulation where the particles are being blown away with some minor noise and each particle is given a lifespan so it dies and doesn't stay too long. Originally, the particles are being turned into density and be used in DOP with smoke solver for simulation (add disspate, turbulence and disturbance) to get the look of smoke trail but the results isn't really working and not what I'm looking for. I then tried to use the particles as density and just piped into cloud noise to randomize the density so it looks okay-ish but my question is it possible to get a fairly decent looking smoke trail with my setup or is my setup direction wrong? Thanks Sc01_SmokeTrail_v01.mp4 AirPlane.hip
  5. TINY TRAIL ISSUE

    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
  6. Hi all, Is it possible to create a curve or a line from an animated object? E.g if I had an animated sphere, would I be able to generate a curve from its trail or path (instead of creating the curve manually) so that the curve follows it?
  7. particle trails fading

    hey! sorry for the dumb question, but I couldn't find an answer I have a pop sim with some points, and I'm trailing them with the trail/add combo, it's all good but I can't find a way to map Alpha or color to the length of the trail to let the trail fade away, any idea? cheers!
  8. Hello, I have a feeling this is a common issue, but its a bit hard to explain / search for a solution. I've imported an animated alembic file, used unpack to get the points and put it through a trail node to get the point velocities, the problem is that the point count changes as some of the objects "disappear", so you get brief flicks of extreme velocity as the point IDs shuffle, I am curious about the method(s) for dealing with this problem.. Thank you
  9. Hair effect? (flow/er)

    Hey magicians, I'm trying to study an effect I saw on flow/er by Lukas Vojir: Here are my thoughts about it: 1) Make curl trails and convert them to hair somehow to get that movement? or wires? 2) Create simple flip with curl noise and advect trails? So far I run some tests, I can get a similar result in static, but I cant give that movement, it is possible to convert advected trails to hair/wires to get that? or there is another better approach? Thanks in advance Cheers!
  10. Explosion Trail

    Hi, What is a good way to get good looking tendrils/explosion trails like in the photo. Everytime I attempt this look, my sim just winds up mushrooming out and I can't get the motion I want. Here is the full video of the reference: https://youtu.be/obmbR4lP6Ws I have tried many things. I tried emitting from particles and used the trail sop to create a trail of particles, I have tried emitting from just a few particles, I tried geometry, but I can't seem to get the look that I want. Here is another sim that I did where you can see motion is not that great. https://vimeo.com/262084530 Thanks
  11. Trail SOP help

    Hi all, I'm having what I'm expecting is a very simple issue with the trail SOP. As my points are dying/ptnum is resetting, I'm getting glitches at the ends of my trails. Obviously if it was a POP sim, I could just trail > cal vel, then append an add SOP to ad a primitive based on id, however I can't figure out how to do it using the @ ptnum variable in the attribwrangle. Is @ ptnum is actually just the wrangle variable, and not actually the point attrib? Been scratching my head on this for a while. .hipnc attached, any help very much appreciated.broken_trails.hipnc
  12. hi guys as the title says really i've got an anim i imported - i dropped down a trail sop compute velocity and now i want to turn that into normals. I tried attribute promote and a wrangle with @N = @V; but it didn't seem to work can anyone advise me how to go about doing this? end result is having some control of a pyro sim around a character eg smoke swirling up and around his limbs so i'm using a tip by Ben Watts to try and blend those animation normals/velocity with normals that simply face upwards. Theres probably other ways to do this but i've no idea and tbh this whole thing is just an guessxperiment heh heres the tut i was looking at....
  13. Asteroid Dust Trails

    Hey guys, This is my first post here! I'm new to Houdini and learning a lot from the shelf tools, available tutorials, forum posts and documentation. Now I'd like to create dust trails from shattered asteroid pieces. Here is what my trail setup looks like so far (.hip attached): I'm almost happy but a few things should be improved/fixed: The "Source Volume" node doesn't know the torus' velocity when drawing into the density field, which results in stepping. I'd like the smoke to interact with (flow around) the geometry. Can I draw it into an obstacle and/or velocity field? Merging the solvers didn't help yet. Maybe I could modify the air pressure/resistance aroudn the asteroid and ignore it for the smoke that's far enough away? With the "Gas Resize Fluid Dynamic" node active, there's some strange aliasing happening towards the end. Any tips on how to achieve/fix those issues would be great! I've been searching the forums and several tutorials already. But as today most of them are not written text but videos instead, it's hard or at least very time-consuming to find specific information. I'll keep playing with nodes and parameters, watching volume wrangling tutorials and also try preparing an upres setup. Thanks! Hebi 2016-08-04_asteroid_trail_v002.hip
  14. Thread Unwinds Forming Shape?

    Hi All, I am trying to implement a concept of a spool of thread that unwinds leaving a trail that then takes on the shape of the classic "support this cause" ribbon. I have started with Matt's Pop Trails example file and replaced the scatter with an Object Merge of a single point from an external object that tracks the spools Z position. This gets me a single thread trailing the spool. What I don't know how to do, is to make the trailing thread take on the proposed shape for the concept? Is this Pop Trails example the best way to handle this or is there a better approach? Thanks ap_me_pop_trails_spool_thread.hipnc
  15. Hi there, this is my first post here. I'm moving my first steps with Houdini and, coming from 3ds Max, I'm trying to find out how to get similar results in the Houdini world. One type of setup which I use quite often in 3ds Max is Pflow Spawn. Basically in this case I've some particles emitting from selected vertex of a moving object, in other words I use the moving mesh as a particle tracker. By doing so, it's easier for me to drive the particles, I can also add deformers to the mesh which will affect the position of the particles as well. Once I'm done with this first step, I spawn the particles, which in Houdini I would translate with Trail. This is what I get with Pflow in 3ds Max: I tried to create a similar setup in Houdini with the following steps: - I created a plane and animated its position/rotation - I created a Source Particle Emitter (it's emitting from a vertex group) - I deleted the Gravity, in order to keep the particles following the plane - I added a trail in the Source Particles, but the result is not what I'm after and, with a lot of particles, Houdini gets really slow This is what I get: So, I guess what I'm trying to figure out is: 1) Is trail the only way to generate a mesh from a particle source? Maybe I can I generate splines? in other words, I'm trying to get a real geometry 2) If trail is the way to go, is there a way to improve the performance and get a smoother experience? I've attached the file I'm working on. Thanks for any help. particle_trail.zip
  16. Particle trail length

    Hello, its my first time posting here. I am using a particle network to generate trails using the trail SOP. In that trail SOP, I would like to give each trail a different length but I have no idea how to do it. Thank you all. particleTrail.hipnc
  17. Solutions for whispy smoke trail?

    Hi guys, I'm trying to create small explosions of fireworks, seen in Harry Potter (1:23 - 1:25): I've created the particle explosion, but now I'm struggling a lot with creating the whispy smoke trail the those particles leave. I see tutorials about those big, high density smoke trails (rocket smoke trails for example), but not about subtle, low-density, whispy smoke trails. What would be a good solution to create this kind of effect? I've added my hipnc file so far, with the explosion, if that may be of any help. Thanks a lot in advance! Felix fireworks.hipnc
  18. Particle motion question...

    I'm a newbie in Houdini and I'm working on creating fireworks. I have this question, it maybe simple but I've worked on try to solve this for an afternoon... How could I make the firework trail to be thicker at the top? (Like this and this) Right now my firework trail is looking something like the image below. Is it something to do with the pscale? And could anyone tell me how can I achieve this? Thank you very much. particles.hipnc
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