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Found 115 results

  1. Exploding vellum grains

    Hi guys, I'm currently trying to setup a test of vellum grains with loose sand and clumps falling from 1m down on a pighead-collider (grain size of around 0.001). I did lots of tests already but can't manage to get a stable result where the clumps (more or less) keep together on impact. They stick together mid air, but as soon as they hit, explode and spread in numerous pieces. Scene and sim is according to realworld scale. Settings I use are all default but: Common-Tab: Substeps 12 Constr. Iterations 2000 (That high since I was told it needs to be roughly the amount of grains you want to pile up, and having grains around 0.001 in size makes pretty huge stacks.) Static Friction 0.75 Dyn. Friction 0.15 Advanced Tab: Repulsion: 1500 Attraction weight 1 (weighted/multiplied with a point attribute (0 to 1 values) that defines loose sand and clumps based on a noise pattern.) Attraction 100 It would be very cool if someone help me figure out why this is not working. Any hint or even a example-scene is much appreciated. Thanks in advance for your time!
  2. Emit Time Range till End Point

    Hey Guys, i got a question. I got a vellum sim and i am emitting every 8th Frame one sphere into my sim. I did it with -> $FF % 8 == 1 but now i want that emission just between Frame 1 - Frame 48. So between F1 and F48 i want every 8th Frame an emission. How can i get this with an expression? Cheers and Thanks!
  3. Finding the Min/Max values in a field?

    I am trying to figure out how to get the converse of a field, mathematically. I am attempting to blur a Cd field in using a Gas Blur microsolver. I have some mixed results, but I want to get some finer control over the radius, namely that I want it to blur more as it slows down. I have used the gas analysis microsolver to get the speed field by taking the length of the velocity, but I can't figure out how to get larger values to be in the lower speed areas. Obviously I would love to use a fit to invert the values, but I am struggling with an elegant way to get the minimum and maximum values for a given field. I could easily just do a loop in a wrangle and get the min/max values that way, but that is going to be extremely slow as this is a very large, dense simulation. Is there a simple way I can get the min/max values in a field so I can use fit(@speed, min, max, max, min) in a Gas Field Wrangle node to get the converse of my field?
  4. Vellum use imported restscale attribute

    Hi all, I can not get my vellum sim to use an updated restscale attribute. It is animated on sop level (see image 1) and merged into the sim in a sopsolver with Data Name set to 'ConstraintGeometry' (see image 2). The animated attribute is in the sim, but it is not used. I attached a simple example .hip. vellum_restscale_import.hiplc
  5. Hi Everybody, I've got a few (hopefully) quick question about Vellum Constraint Attributes! So I'm basically using the vellum grain solver, with a custom constraint network made in SOPs. I've been able to get what I think is correct behaviour by adding my own attributes for "type", "restlength", "stiffness", "compressstiffness" e.t.c However I noticed that there are some attributes that the Vellum Solver seems to add, such as "pts[]", "stress", "L" & "typehash". Not a problem so far, except when I add a SOP solver to my DOPs to dynamically add constraints these attributes are missing. I've been able to get my constraints to work by correctly setting the "pts[]" attribute, however do I also need to be working out the "stress" and "L" values? Are "stress" and "L" influencing the solver, or are they more like data out attributes? Finally, do I need to worry about the "typehash" attribute? I can't easily upload a scene while I'm at work but if you guys think it will help explain my situation better I can do it when I get home! Thanks in advance! M
  6. Ran into an issue while learning DOPs. After having setup Vellum in SOPs I'm trying to import the setup in DOPs. At first everything is fine and dandy, but if there is a Transform added to the geometry on object level then only the GEO that's imported into DOPs network is updated. The Constraints are still in their original position. Is it possible to update Vellum constraint location when the object node is transformed? Adding a basic example file with the issue. test.hipnc
  7. I want to create hanging wires using DOP wiresolver, I followed this tutorial on Youtube: https://youtu.be/fkJOzHY8fOo But in my setup the simulation is not starting. Please help Hanging wires.hip
  8. hey ya'll, i'm trying to animate the restscale of each emitted hair strand based on age but i'm currently stuck because "@restscale" is erroring out on the vellumconstraintproperty inside the dopnet. any ideas would be great! thank you! chris anim_rest_scale_age_v001.hip
  9. RBD's and SOP Solver

    Hi peeps, I'm using the SOP solver DOP to change my geometry overtime from one sphere to multiple spheres, however, when the geometry changes to multiple spheres it's still behaving like just one object instead of individual spheres and I can't figure out why! Any help would be much appreciated and I've attached the troublesome scene file. Also, I used the RBD Fracture object for this instead of the RBD packed, because I couldn't get the results out of the SOP solver to work with RBD packed object. I unpacked the geo in the SOP solver and repacked the output with the name attribute and it wouldn't work, so also, if anyone could shed some light on that as well it would be much appreciated. Thanks. RBDs_SOP_solver_testing_01.hip
  10. GRAIN STICK ERROR

    Hello Dear Houdini Community, I have been trying for hours to solve this problem. I have a simple simulation with grains, the basic idea is when the particles touch the surface more often they stick to it. they do not do that, they all disappear to one point in the scene, actually always 0, Y value, 0. Can someone look at it? Sincerely, Tim grain_test_collision_stuck.hip
  11. Vellum string constraint break

    Hi everyone, I'm currently having trouble with breaking a vellum string object in half. The idea is to make a saliva strand that's stretching before breaking in the middle. Currently i have a line that's vellum string, attached at the top point via "pin to target" constraint to an animated object. (string constraints are SOP level, fed to DOP node, with "pin to target" constraint done within the sop solver "forces" subnet) Sim follows the object, and i can break the "pin to target" constraint itself via the vellumconstraintproperty node, set to the group with the top point. I tried various ways to group the centre point of the line, and keyframe another vellumconstraintproperty node, but it doesn't work. Can anyone enlighten me on the proper way to break string constraint points in a keyframe-able way instead of just using stretch stress? Thank you very much in advance!
  12. Hi guys, I'm trying to save out a file cache of a simulation and then import it into a different DOP net to use it for collisions with particles without the particles changing the file cache Geo. Any help would be super appreciated.
  13. slicing object while simulating

    I'm trying to slice an object during a rigid body simulation. imagine a fruit falling through a grid of laser beam. the object is supposed to be sliced in multiple pieces. i can't pre-crack the geometry as the fragments depend on how the object hits the lasers. like this,
  14. Help with multi solver

    Greeting all, I am trying to wrap my head around the multisover in dops. I have a sim of a plank breaking. I have upacked the sim and placed a debrissource node after. I then copy cubes onto these points and point a pop source to them. I have a packedrbd object running into the multi solver which runs a pop solver then a rigidbody solver. It kind of works but when the cubes hit the ground the shake and jitter and generally misbehave. Any Insite into why this could be happening would be greatly appreciated. I have attached a sample file. Cheers! B plank_troubleShooting_v04.hipnc
  15. Hi. I'm struggling to solve what should perhaps be an easy problem; - Release a fixed number of points with an animated point attribute, using POP's. Here's what I'm trying to do; - Take a packed object of fractured pieces. - Pass it to POP's. - Treat all objects as static as first. - Then release each object using POP's, using an animated point attribute. - Use transformpieces to animate the packed object. I'm able to do this with the RBD solver, but it takes an incredibly long time. I don't need the accurate collisions of RBD, but really need the speed of doing this with POP's. Below is a side-by-side scene showing the setup working if I animate the particles using @P, versus my setup that doesn't work because it relies on an animated attribute that doesn't get passed through to the points (because they are born on frame 1 and have fixed attributes). Help really appreciated! clinton release_particles_from_animated_value.hipnc
  16. dynamic bones

    I'm working on a project where I need to hand animate a snake-like character doing spirals and twists. Investigating approaches, I came across this video, where the guy basically gives a bone chain wire dynamics, and is able to get some really nice overlapping tail motion, just from animating the root of the chain. At 9:00 of the video he starts to add dynamics, and you can see the animation effect I am trying to achieve at 12:50. My goal is to find the easiest way to get overlapping tail motion, by animating just the root. So far I'm just trying to get a wire to behave nicely and not explode from a simple sine wave animation, nevermind getting the bones to move with it. Any rigging experts have advice on how to approach something like this in Houdini? Thanks!
  17. How to Transfer UVs to Vellum Grains

    Hey, has anyone tried this yet? In the past when creating FLIPs I would normally carry UVs through DOPs using an attribute promote to carry the UVs from vertices to points, but it seems like this is not working when applying the same methodology with vellum? Please help!
  18. Colored Smoke with CMYK

    Last week a guy asked in the brazilian houdini group, in facebook, how to simulate colored smoke. I believe there are lots of hip files with this kind of effect, but while thinking about it, it came to my mind the possibility of using CMYK instead of RGB, since cmyk is more suitable for mixing colored things other than light. I couldn´t spend more time testing it or improving the file, but it seems to work, so here´s the hip file. colored_smoke_V002.hip
  19. What XSI | ICE "Project a vector" equivalent on POP/VOPS? reference: http://download.autodesk.com/global/docs/softimage2014/en_us/userguide/files/iceref_Project_Vector.htm the node on XSI returns 3 things: RESULT LENGTH VALID any ideas? thanks in advance!
  20. Import Pop Field into SOPS

    Hi all I'm looking to replicate a Houdini sim that I have inside Unreal Engine. I would like to export my vector fields as flow maps that can drive Unreal's native particles so that they still remain interactive (collisions, emission, etc). I'm having trouble accessing some of the native POP fields outside of DOPs. Can anyone explain how to import a POP field such as pop axis force out of DOPs into SOPs so that I can then export it? Thanks! Nick
  21. Group in dops [SOLVED]

    Hello ! I'm trying to apply a force in dops to some packed geometry based on some rule. For the test, I use a group that have "@P.y<2.5" in its expression box, and use this group inside of a drag node. But for some reasons, it's not working properly. I never used the group node in dops before, so maybe I'm missing something. Not working properly being the force still applied to the geometry, even though the geometry is clearly above 2.5 in y position. Anyone have an idea ? Thanks ! group_in_dops.hipnc
  22. Link to tutoial -> https://gum.co/imSYS In this comprehensive stand alone tutorial we will go over how to set up scene-scale clustered pyro simulations and blend them together post-simulation to make it appear as if it is one large simulation. This process will lower simulation time, allow for higher resolutions, and be more efficient when saving to disk because there are fewer voxels. This process will also optimize large scale pyro scenes, so that simulations are only calculated where absolutely necessary and blend them together so that it appears as if it is the same volume. This tutorial comes with all digital assets, a documented and fully set up file as well as a starter file for following the tutorials along the same as I work through them. An intermediate tutorial for those looking to speed up their pyro workflow, learn some VEX and create massive sims. Includes a documented scene file and all digital assets! Hope to see everyone leveraging these optimizations in the future to create massive simulations and squeeze in those extra few iterations before deadlines! You can reach me at trzankofx@gmail.com for questions or comments.
  23. Glue Constraint Gravity

    I have been spending some time creating and destroying a building in Houdini but am currently hung up on a constraints problem. In my hip file I have my procedural building, I fracture it, and send the pieces to be constrained together. I haven't meticulously created the constraints yet, I just wanted to get everything in and working first. When I run the rbd sim a ball crashes through the building and blows the middle part of the building away but the top part of the building just sits there floating in the air. Not exactly sure what I'm doing wrong here, if anyone can point me in the right direction I would greatly appreciate it! The hip file has a top level control node to cache everything for you to quickly test skyscraper_destruction.hipnc
  24. Hey guys, I am really stuck with this one. I was told it is impossible to change the scale of a piece inside of DOPS while it's simulating with the bullet solver. I have achieved something similar where the piece goes into dops, gets out of dops, gets transformed in the scale, and then goes back into the same DOPS sim in a loop. So it creates overtime shrinking. But now I need this to happen inside of DOPS. I´m pretty sure it´s possible. Does anyone have a clue.
  25. Hi Guys, I want to scatter some points on a growing and deforming vdb mesh. These points shouldn't jitter on the surface and look like they are moving along with the surface. I have attached a basic file similar to my actual setup. Basically, I am going to render these particles as bubbles on top of the mesh and I want it to be quite dense. I haven't been able to figure this out and couldn't find much help online. It would be great if you guys can check it out and help with a response. Thanks vdb mesh vdbscatter_v01.hipnc
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