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Found 164 results

  1. 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
  2. Hi, Is there a way to do @disableexternal on each object individually ? I would like to disable it for one object but not the other. Thanks !
  3. Hi. I want to change glue constraint strength depending on which object hit it. Here I want that center toy is weak, right toy is strong collider. https://imgur.com/sFXmBTO.mp4 I don't want to change the strength with keyframes, as we are actually expecting a fairly complex RBD. I want to reflect collisions that appears dynamically in DOP. I think we can use Impact point search with SOP solver. Now I want to make it in RBDBulletSolver because of H18 guide constraint, but its DOP's SOP solver of constraint is little strange. It seems to be not able to use additional SOP solver (?) https://imgur.com/EiUKQyc.mp4 and SOP solver named "Constraint_Solver" we already have cannot read impact with "Error: Infinite recursion in evaluation..." So does anyone know import Impact DOP data to RBDBulletSolver's "Constraint_Solver"? or another solution? I don't really understand the data structure of the DOP, so I'm assuming it's a simple specification. import_impact.hiplc
  4. realistic sparks / embers

    Hey folks, I wanna do some pyro work. To make that look convincing I need realistic sparks. I tested a little bit and watched tutorials, but the sparks are not really convincing. Like it seems there is no temperature and they are way too universal. I would appreciate it if someone would be able to help, because I feel like I searched the whole web and there is no Documentation really. I saw how Rise fx did it for Doctor strange, but that was very briefly (here is the video: https://www.youtube.com/watch?v=I6-HW34e0WA). Im a beginner in Houdini, so dont be rough on me. realistic sparks.hip
  5. Hey folks, I started with Houdini very recently and I wanna focus on fx at first. So after trying with the Shelf tools I wanted to stylize my sims. I looked around the web and followed tutorials on a particle based pyro sim (I wanna do an explosion). The problem is, the pyro sim won't work with my PoP really well. I considered that my particles are too fast maybe and added substeps. But that didn't work out either and I don't know how to fix this thing. I hope you could understand my issue. Help would be much appreciated :^) Impact explosion.hipnc
  6. Hey fellow magicians, I am struggling to find a way to remove intersections on a bunch of scattered and randomly rotated primitives that are not spheres. I am trying to create a set up where a series of repeated elements are scattered in a volume and pushed away from each other just enough to remove intersections between them. So far I have tried to get this effect working through vellum colliders, popgrains, and rbd as well as trying to fake it through Spheres from VDB compenent. My main issue working with particle sources - it doesn't give me enough control over element distribution. This is why I am trying to find a way to generate the geo first and remove overlaps second. Nothing is working, I feel like this should be a pretty straightforward setup but I am not sure what would be the best approach to it? Any tips would be amazing! remove-intersections.hipnc
  7. Volumetric Temporal Deflicker 2.1 to Houdini 12.1 to 18.x Deflicker VDB/Fluids by analyzing areas of voxels, creating temporal volume gradients and use this info to interpolate those areas based on temporal volume falloff. It is very good at deflicker slow-motion fluids. Very easy 1 node solution to your flickering fluids or VDBs/volumes in general. Available on Orbolt (normal and studio versions) at https://www.orbolt.com/asset/RodTD::Rod_vdb_averaging Available on Gumroad at https://gum.co/deflicker Rod Tebisx | Senior Creature FX Technical Director at Framestore London Overview:
  8. 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
  9. Animated Pyro to Sop to Grain

    Hello Okay; Im starting with a sop with animated noise and transform, extract the velocity, which feeds my Pyro dop. After im using point deform on the result to output an animated poly sop model from the pyro sim. I was curious to add interaction FX using Grain with the resulting source. To have my pop source not static in my DOP, the only way I found was to have an impulse activation like $$F and a life expectancy very low (like 0.02, itùs in sec...). I have a few collision obj and forces. If i use a static activation like $$F=0, the sim reacts nicely and my object splash and roll, spread off on the floor and collide with objects like i expect. With small life, the particles dont reacts to the gravity, force and so. Which it's logic Afterall they are dying and being regenerated every time from the source position.// Maybe Grain is done designed for animated objects, or did i miss something? Thanks for your input, stay safe vincent* ________________________________________________________________ Vincent Thomas (VFX and Art since 1998) Senior Env artist & Lighting & MattePainter & Creative Concepts http://fr.linkedin.com/in/vincentthomas https://www.imdb.com/name/nm085962
  10. Hello, fairly new to Houdini here, I am having problems with a simulation. It should be fairly simple. I am simulating a animated object that is coated by a fractured RBD object and fracturing the object by using a SOP solver by Group Create with Bouding Objects and Attribute Wrangle with 'i@active = 1;' This simulates fine, except the Animated Static Object becomes active when a bounding object covers it and is triggered and starts to wobble around inside the half fractured coating. Is it possible to keep this Animated Static object from being activated? Any help would be appreciated.
  11. https://i.imgur.com/FsowZvp.mp4 Take a look at the above example. I'm transferring the Vellum i@stopped attribute to some cloth that is covering an object. I'm using a flat grid that animates top down over the surface while transferring the attributes. My issue is the i@stopped attribute is turning off again as the pieces of cloth fall away, outside the range of the attribute transfer. Is there a way for me to transfer the attributes and have them stay on the Vellum cloth once they've been transferred, no matter where they float away to in the scene? File attached (apologies it's 9mb - The statue geo is frozen in the scene). Fabric_Tear_v01_temp.hipnc
  12. dopimport y=0 is not y=0

    wired: working on a big destruction file. And always got another result as I assume. So made this tiny file to check the similiar steps one after another and found following: After importing the small cube with y and ty = 0 into dops it isnt 0 anymore. Only after 50 frames it level near 0. But not 0. only with a checked "compute mass" and density NOT 0, y=0. As soon as I change the density, the y component change. Why is this? Looks like the atoms have come to rest... ;-). But seriously, is this wanted, an if so, why? gluetest_2_objects.hip
  13. The documentation is very unclear. In the vellum constraint DOP, it says that I can use the activation parameter to update constraints at a certain frame. When I set the creation frame parameter and activation parameter to the frame where I want my constraints to be updated, nothing happens. The only way I can get my constraints to update is if I set the "update constraints" parameter to "every frame", but I dont want my constraints to be updated every frame, I only want it updated once!
  14. Hey there! I'm quite new in Houdini. I do not really like to ask questions, I rather tend to find answers by myself. But sometimes I hit the wall. This is the case I need your help guys. Im trying to make RBD sim in DOP NET with the simple spheres. My goal is to have variable scale and color of a sphere according to the noise. I manage to get color with POINT VOP in SOP SOLVER with MULTI SOLVER. But I stuck with the scale of a spheres. They inherit pscale from a GEO level. I would like to use pscale in DOP NET and manipulate it with the POINT VOP. Any ideas how to achieve it? I tried to make it with the particles, like in this tutorial https://www.youtube.com/watch?v=qXoSEnh94YQ&t=246s But particles tend to move erratically and not act like proper RBD. Balls on plane.hipnc
  15. Hi everyone, In the case of an RBD simulation with constraints, is it possible with a sop solver to copy or transfer the constraint attributes and broken group (which comes from the relationship_geometry Object Merge node) to the dop geometry? Basically I would like to use these attribs (angle, distance, torque, etc.) and broken group after the dop import, but I can't really get them. Do you have any idea?
  16. What is the best workflow for adding particles / liquids to a flat tank simulation setup. Think of barrel that is spilled or a hose that is pumping new liquid into a flat tank simulation. I somehow figured out how to add some volume velocity into my tank but can't quite understand how to create or spawn new particles into it. Being a beginner I would appreciate a thorough explanation. Thank you.
  17. How to add color gradient through velocity plus collision to influence color velocity? to influence the color such as this one here: https://vimeo.com/59024762 how did he do, but he used xsi softimage. if possible to make a Houdini?
  18. Hi everyone! I'm currently going through the Procedural Cities in Houdini Tutorial from Pluralsight. So far everything worked out great. I had to adjust some nodes (As the tutorial was made in Houdini 15) But it's working. I'm now in the process of aligning bounding boxes of Buildings to the geometry surrounding them (e.g. rotating the buildings so they face the streets) Using a bulletsolver and popattract. In the tutorial video this simulation runs smoothly... when I'm opening the exercise files on my Computer it runs fine too. But with my own file the viewport runs slow (like 1 frame every second) The perfomance monitor shows this: (The dopimport took even more time but I bypassed it here to see if the problem was somewhere else) I'm not sure where to check for the __DopDetailLook_Guide or how to influence it. But it seems to be viewpoert related, as entering a framenumber in the timeline simulates super quick and gives the right result... So this isn't really breaking anything as I can get the correct result anyways without waiting forever, still I would love to know why the simulation runs so poorly in the viewport. If anyone wants to see the hipnc file I'm happy to upload it somewhere. Any help would be greatly appreciated! Cheers! Daniel
  19. Hello, I'd like to perform matrix multiplication between 2 of 3x3 matrices(not coefficient-wise) and outer product between 2 vectors using HDK. So I'd like to know if the * operator supports matrix multiplication and outer product of vectors as in the example code below. UT_Matrix3 A = ... UT_Matrix3 B = ... UT_Matrix3 C = A * B // matrix multiplication UT_Vector3 u = ... UT_Vector3 v = ... UT_Matrix3 X = u * v // outer product If not, is there a function/operator to do matrix multiplication and outer product? Thank you.
  20. Hello, I'm trying to write a microsolver that changes the scalarfield's voxel value according to the points position of the given geometry. So, I'd like to know how to access the voxel data of SIM_ScalarField by index vector without iterating entire field. For example, changing the voxel value in [2, 10, 6] to 1. Thank you.
  21. Hello there I was looking for a solution on how to simulate two smoke objects with different density fields and still have them interact. I couldn't find a solution from a quick search so I thought I'd post here now it's resolved. To achieve this result you need to dive inside each smoke object and disconnect the velocity field. Copy the velocity field creation dop from within an object and attach it with an apply data beneath the merge where you bring the objects together. Set the data sharing parameter on this node to "Share Data In One Timestep" and you should be good to go. You could also share more fields between smoke objects if you don't require individual data for both I've attached a hip file All the best, Lucy multiObjectInteraction.hipnc
  22. Vellum + other simulation (rbd)

    Hi all, I am trying to figure out a way to let a vellum simulation interact with other simulations. In this case I want the vellum donut to collide with the chain simulation I made. My thinking was to do this through a dop import field. However there is no collision between the 2 simulations. Does anybody know how to achieve this interaction? Cheers! Chain+vellum.hiplc
  23. Hey guys, I need to create an effect like those in the reference images. I've started with a pyro sim with a high velocity on one axis to push it in that direct and then I'm adding noise to it as it slows down. I'm then adverting particles through the vel field however I am struggling to get the pro sim to expand like a cone shape like those in the images If anyone has any suggestions that would b fab Cheers
  24. Teleportation effect

    Hi, I recently finished this little teleportation effect. Some of it's based off of "applied houdini particles VI", but converted into 3d behavior. CC is always welcome:)
  25. hello guys! I have a pop sim that runs for like 30 frames as they fall .. then I want to revert(attract?!) them back to their initial position (as they were before falling)... I tried the per point attract on the attract node.. and I get their positions back .. how can I get their orientation also to be targeted to the initial orientation?
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