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Found 100 results

  1. appearing grains over time ?

    Hello everyone, I am making a grains simulation that has a very long object (red box) for particles. Is it possible to make grains appear during the sim time (while my ship is getting closer to the grains), instead of showing all particles at the same time? That way I could save some sim time and instead of 5mil points, simulate around 1mil that is needed at that moment. I'll attach a low res sim video of what I have for now, so that it would be easier to understand what I mean. LowRes_Sim.mp4
  2. popAwake with Vellum Grains

    Hey All! Question! Does the popAwake node work with Vellum Grains? I am placing it after the vellum source but it doesn't seem to have any affect? I'm not sure if i've made a mistake or if the popAwake node simply doesn't work with vellum? Thanks!
  3. hi all ! I have a basic vellum grains setup. I need to modify the clumping to make the grains stick together less and for the grains to move more freely. Any suggestions which setting in the grain solver I should be modifying?? Thank you!
  4. Help with Grains & RBD's (beginner)

    Hello, My issue I am facing is getting geometry(mushrooms) to interact with grains (soil). I've tried setting the geometry to a RBD hero object and the grains as collision geometry however this is not working. Any solutions would be greatly appreciated thanks:) Mushrooms.hipnc
  5. hi folks, I am trying to master my first Houdini project: an excavator digs a hole into the ground. What is causing the grains to jump out again, once the shovel lifts up? Could it be mass related or is it something that forces the grains to rest in their former position? D'you have any ideas? *D Please take a look at this small video: 01_construction_site_v4.mp4
  6. Finished my first tutorial, hopefully you find it helpful learning Houdini!
  7. Hey, I'm currently trying to get my skeleton object to interact with my vellum grains sim, I want it to start from sleeping and get awakened by the character animation pushing through it to imitate snow. Any help would be appreciated! If you could explain more, how/why this makes sense to Houdini will be even better to build my understanding for the program as I'm still a noob Snow_Crawl_2.hip
  8. 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
  9. Grains to object

    Dear friends I´m a new Houdini user and I´m trying to do something different from most of the sand sims. I have a thread of sand falling from the hole of an hourglass, and I´m trying to do build a sand object as the sand falls on the container bellow the hole. The question is, how can I direct my sand particles to become the object that I want? Any suggestions would be appreciated. Thanks in advance
  10. Polygon mesh from grains?

    How do you turn a vellum grain sim into a polygon mesh? I feel like there has got to be a simple way of doing this, but all my googling has turned up solutions requiring building polygonal geometry in VEX. That seems like overkill for just a simple use case. Thanks for your help!
  11. i m still new to Houdini its been a month now, and I have hit a wall I m Currently trying to animate a character walking on sand and I want to use the Characters Geometry to activate the Grains. Problems: 1. I tried Importing an FBX Character and using its geometry as a source to activate the Grains....not working 2. I tried Importing an Alembic Character and using its geometry as a source to activate the Grains....still not working On either Case the grains continue to fall they do not SLEEP....... Please advice on best practices or please refer to tutorials
  12. Hey all, I'm trying to play with a scene where I'm doing some explosions on a beach and I wanted to make sure I had all of the individual effects down before I started trying to do the large scene. I already figured out how I want to do the explosions with a sparse pyro, and I got the grains solver to behave how I want for the sand to be kicked up, but when I tried to add a pyro solver to the sand grains I got some weird results, so I went to make a simple example scene that would be faster to simulate and it started doing even worse stuff. My grains scene is giving me some really bad smoke that doesn't seem to be advecting and is only generating on each frame of my cached grains. Seeing this, I found an example file which was using a pops simulation to generate smoke, so I tried to apply what was in there to a simple test scene, and for some reason my sims are applying giant black box sprites to the particles before it even gets into the pyro simulation. If you have some advice on how to handle the dust from sand explosion that would be great. If you have any idea why I'm getting the sprites, that would be amazing as well. The files aren't the cleanest, but here they are. I am using GridMarkets caching and rendering for the sand file, so if you don't have their nodes you can just delete them and replace them with filecache nodes. SandboxPop.hip pyroFromParticles.hip
  13. Vellum Grains - POP Spin / POP Torque

    Hey folks, simple question... is it possible to use the POP Spin or POP Torque (DOP Nodes) on a Vellum Grains sim. I am emitting Vellum Grains continuously and after the sim i use the Grains to copy f.e. Boxes onto the Points. But i can't get the Geo to rotate. They stay static at one axis and don't rotate. So my question is: Is it possible to use POP Spin or Torque on Vellum Grains? Cheers
  14. Been getting back on the houdini train, this is my second attenmpt to get onboard from a few years ago. Thanks corona... Im trying to get comfortable with houdini caching before I start upping grain counts in vellum. I have been using the vellumio node to create test files (saving as .bgeo so far, .sim isnt on the save list) but when I toggle the node on it won't scrub, it just shows as the last frame of the sim, unless I go into the node, then it will play. I have load from disk checked. Can someone walk me through this? Is it even necessary to cache? Will save to disk in background keep caches after a restart? Thanks
  15. Post-grain sim constrained RBD animation

    Hi there, if anyone could help me wrap my head around this I would be very grateful. My setup is this: Vellum sim with grains falling into a container. Motion is exactly what I want. I need to then copy cubes to these points to look like ice. I'd like to have close to realistic rotation on the ice cubes as they simulate. My thought was to run an RBD simulation on the cubes having them constrained to their positions as defined by the grain sim. The problem I'm having is understanding how to create constraints on the cubes that allow them to freely rotate but maintain the grain sim position. I'm in H18.0.287, and I'm attempting to use the sops rbd solver workflow, though I could see needing to configure this with the normal dops workflow. Could anyone point me to some resources to help me understand how to build these constraints? Or maybe I could somehow get rotation without this secondary simulation? I could've sworn there was a way to get orientation from vellum grains. Thanks everyone! As a treat, here was an attempt at a bullet solve with a cheap buoyancy force I hacked together haha shrub_010.mp4
  16. Hey Guys! I'm trying to find a way to interact Vellum Grains with curves using Vellum Hair/Cloth. Attached you can find a test scene where you can see an simple example. In this example there is a switch node with three different setups: 1) Hair 2) Grains 3) Cloth My goal is to have both interacting with other, in a mutual setup. But only grains seems to work... But not as I expect, cause I'd like to have a stiffer line behaviour. I know hair can give us this, but how to make them interact? Thanks a lot! Cheers. grains_interaction_test.hiplc
  17. How to approach Flour in Houdini

    Greetings, I'm trying to achieve something like this https://www.shutterstock.com/video/clip-24306053-slow-motion-falling-eggs-into-flour-stock Forget about the eggs, generally I'd like to simulate a collision on a dust / powder like flour. First of all, how should I approach this effect? Particles or Grains? And if I choose Grains, should I use the normal Grain Solver or the Vellum one? On the picture below I have a setup that I used the standard Grain Solver, and 2 RBD object, on is the static plate, and the other one is the moving ball. I encounter many problems like the ball bouncing really hard on the flour, instead of just landing, and if I change the RBD Solver priority in the Merge, then the Grain collide merely good with the ball but they pass through the plate. So basically the Solver can't read both the RBD objects correctly. Also, after all, I need to use a custom Force to "Explode" some Grains in the air, because it seems impossible to happen with just the ball collision. Thank you in Advance !!
  18. Vellum grains

    HI Houdini Guys, Does anyone know , how to add random mass to vellum grain clumps, so that the bigger clumps falls fast. "context is that is that a creature comes out of ground and i need to add mass for the clumps, which is done with vellum grains." i tried using drag with mass option. but that did not work. sorry i cant share any hip file, Thankyou!
  19. Hi, I am a beginner level Houdini user and I am trying to accomplish an effect where I grow curves from source points on an object that are dynamic and respond to collisions/forces. An effect similar to this I found some really helpful things on cgwiki (here http://www.tokeru.com/cgwiki/index.php?title=HoudiniDops#Grow_trees_with_particles ) dealing with grains, but I can't figure out how to have my curves grow from my source points while remaining attached. Anyone know a way to accomplish this effect?
  20. 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!
  21. Hi there I made some snow with very small vellum grains What Im trying to achieve is to set an initial state when my snow is already relaxed (I am throwing a box made of grains in top of a mountain), and then to continue colliding with some objects. How can i make the simulation read the first frame and then start writing the next
  22. Constraint on Grains not working ?

    I have a point attribute set on some particles when they emit, I can't get vellum grains to constraint only the point attribute ? Vellum in DOPs; vellumObject > vellumSolver > Output but I don't see the grains on the particles in the viewport either ? Vellum Constraints in SOP's is fetching the attribute in Define Pieces from Attribute but that attribute is not constrained ?
  23. Hi there! I have this problem I need to fix. I imported a fbx animation that has 375 frames and need to chop like a lot, just need from 320 to 375 for making one of the objects a vellum grains of another kind of grains. Im new to Houdini and Im dealing with a lot of doubts like doing this. Is there a simple way? The thing is, when I try to simulate this object it starts from frame 0 and all those 300 frames are not needed. Other way I could make this out is enabling the vellum solver at frame 320 but that is something Ive been having problems with too! Please if anyone could help me out here it would be awesome, there's so much about Houdini I want to learn !!
  24. 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
  25. Hey there, The question, I have a vellum grain sim that I want to export and use in cinema 4d. I have tried exporting it with an alembic but nothing shows up in my viewport. It's a pretty big sim around 6 mil particles. Any ideas? Thanks