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Found 82 results

  1. 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?
  2. 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!
  3. 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
  4. 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 ?
  5. 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 !!
  6. 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
  7. 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
  8. Kill vellum grains?

    Hi, my setup involves vellum grains falling and I'd like to kill the particles reaching a certain position on the Y axis. I tried adding a popkill box within the vellum solver node but it's not doing anything. Any idea?
  9. Vellum grains problem

    Hello friends, I just try to build up a little rbd-vellum grain scene where some geo is interacting with the grains. So far so good. The meshes interact with each other and the solver works. BUT I have no clue why the grains start collapsing in the first frames when starting the simulation. It seems that there is a particle separtaion between the grains that is presolved first or before everything else happens. Does anyone know a solution how to fix this issue or give the grains a "sleeping state" before it collides with the geo? I already tried the popawaken after the vellumsource but with no effect. Thanks in advice, Sebastian vellum_grains.mp4
  10. Wire solver from moving lines

    Hi, I'm trying to figure out a saliva effect and am currently looking at the strands of saliva connecting the top and bottom of the gums and mouth of the creature tgats been animated and brough originally as an alembic (now cached to houdini geo) I've got points scattered correctly on deforming geomettry, then used point deform and add to connect the points, and have been following the entagma connect the yarns tutorial to resample the lines and set the mass for the connecting points to 0. However when I try to go to the next step using a POP network I can't figure out how to have the POP source update the lines and am only able to simulate movement if I create them on the first frame. Is there a mrelatively simple way I can get these lines and their anchor points into a DOP or POP network so I can simulate them to add some movement? I'm looking to mesh them and add then to some drool that im trying to put together using the condensation shelf tool. Any help is greatly appreciated EDIT: figured out the simulation using vellum thanks to Rohan Dalvi, although if anyone could give advice on how to mesh these look close to the strands in this video that would be amazing:
  11. Grains and RBD mutual interaction issues

    Hi there I am trying to get rigid bodies and grains to mutually interact however the grains seem to invoke a disproportionally large amount of force onto the rbd object causing it to fly off into the distance It works fine using one way interaction but not two way. Please could someone more experienced in the matter help me Thanks a bunch For some reason this jammy dude's scene works fine (I'm assuming his is two way as that seems to be the shelf tool default) grainsWeirdness.hipnc
  12. Particles will bounce off a collision object, and I can influence that using the collider's Bounce parameter. Great. However, if I change my particles to grains, they will not bounce anymore, but slide. No matter what I do and this goes for pop grains as well as for Vellum grains. Settting ispbd to 0 is not a real solution, as this means I am not using PBD/Grains, anymore. Any idea? Here's a very simple test scene, using a pighead. Just activate/deactivate the POP Grains node in DOPs. collision_grains.hipnc
  13. Modelling Zen Stone Garden

    Hi there, I am a new user trying to get into the modelling side of Houdini after trying some simulation, and am currently working on a japanese stone/zen garden based on this image. I've found some great examples on how to create the stones (not worried about moss yet), but I was wondering if anyone out there had any idea how to create the combed patterns around the stones. I just finished doing some work with the ripple solver, but thats too realistic in this case. Ideally it would be something more simple involving grains or particles with instanced geomettry building up more based on a simple black and white image that i'd make in illustrator. Apologies if this is too simple a question, any help is very much appreciated. Thanks, H
  14. Hello, I'm trying to create an effect very similar to the one in the reference video, where particles move through this channel and creep over this bubble. I tried different approaches like vellum grains, regular particles and came closest with the lava shelf tool. But then the individual particles are not touching the surface of the bubble and the overall movement of the particles looks too much like a fluid. I actually want the distance between the particles to stay constant. I think some PBD approach would work best, but can't quite figure it out. Any ideas? Thanks in advance. J NanoParticleEffect.mp4 190524_NanoParticles.hiplc
  15. Hi There, I am trying to set up a initial state for a grains sim(that has constraints). I saw those two tutorials about people having similar problem: https://lesterbanks.com/2018/03/initial-state-houdini-simulations/ [lesterbanks.com] https://forums.odforce.net/topic/21727-set-initial-state/ [forums.odforce.net] It seems like that method works for grains/particles that are with out the constraints though…. Has anyone idea how I can solve that ? Thanks a lot for help! Grains_Initial_State_Test_v01.hiplc
  16. Hey, so to preface, I'm a newish c4d user/ total Houdini newb. I created a grain simulation in Houdini and exported it as an alembic, then brought it into c4d. When I imported it to C4d I imported the grains as polygon objects, and it looks fine in the viewport, but when I try to render nothing appears. The way it appears in the viewport The way it appears in render, with a hair material and render apply I did some googling and tried applying a hair material tag and render tag to the alembic particles, and now the material shows up in the render material but it looks nothing like the way it appears in Houdini or in the viewport. I also tried importing the alembic as particle geometry, then using thinking particles to assign geometry to the alembic, but my c4d crashes every time I try to render it. Anyone ever run into this issue before? Thanks!
  17. Hello! I have recently been offered my FIRST FX job! I am familiar with Maya, and some Max, but this job requires that i use Houdini, so now i am all in! VERY EXCITED!!! I have a scene where i have to make some letters rise from sand. The issue is that i cannot get things to collide correctly. Doing my research i have tried using it as a RBD object, and using a trail sop to computer its velocity, but i still dont see any collisions. I use static object, pointing to a VDB smooth as the proxy geo, and all of the collision detection/mode set to volume, but no collisions still. I set the sim up with an initial state file too. Could that be the issue? When i take away the VDB to polygons and VDB smooth, delete and just run the sim as a regular static object, everything works! But...i get some weird artifacts rendering. What is the best approach to this method in Houdini? Im sure the solution is just a setting away, but im lost here. Any suggestions? LetterSetup_001_collProbs.hip
  18. Keyframed Grains

    Hello! I'm a new user of Houdini and I'm trying to do a stuff like this (https://gfycat.com/aptdishonestcow), using a fbx animated character. Im using grains (granular solid) to do the simulation, but i don't know how to start the simulation only at the desired point (The character start running and falls on the ground. I want to enable just when he falls) Someone can help me to do this step by step?
  19. Fur and snow (+hip)

    Hi everyone! The past week I worked on a personal project for learn something about hairs - vellum. It's my first project ever with hairs so I guess is nothing special but several people asked to see the hip file so here it is. Final result: Hip file (I had to recreate it but it should be pretty much the same): groom_clumping_03.hipnc https://andreasbabo93.wixsite.com/sbabovfx/example-files (new version, there was an error on the other one)
  20. Starcraft Growth Project

    Hey there! Trying to be more active. Here's a WIP of a project I did for Peter Claes's Houdini class. Such a cool technique to play around with. Struggled a ton, and have lot of extra RnD elements that got gutted haha. But I learned a lot. Have to Re-Render, have some slime / rivulets for the eggs in the next render, which I have been struggling with. Initially was flip but switched to something simpler and less heavy.. Had issues transferring V for motion blur due to changing pt numbers but I'm sure someone probably could figure it out! Wanted to add one of the eggs exploding. but stretched thin on time. Will do another rnd for it. Will re-render without motion blur I think. Someone had idea of adding veins, like a neural network that activate and reveal. but I failed at that for texturing lol. I think I could brute force it with geometry to replicate it but that just seems wrong. Also I keep running into Lights inside Volumes on my projects.. makes clearing up noise pretty miserable! Will return to this project after school and expand on it.
  21. Hello guys, I'm struggling with making a basic setup with object emerging from the sand with vellum grains. Has anybody done something like this, do I need to use constraints or just pop awake? I'm sharing my basic scene Thanks! grains_test.hipnc
  22. Hi There! quick question about vellum grains. Is there a chance to stick a part of the grain object to the collider? thanks, Balazs grain.hipnc
  23. 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!
  24. Granis collision help

    Started trying to make a Hour Glass effect but when i press play the grains appear on the outside of the geo, not sure what the problem is any ideas? HourglassSim.hipnc
  25. Hourglass Effect Help

    I'm wondering what would be the best way of approaching an hourglass effect where the sand goes upwards. The hourglass has to be taken out of Houdini and into Maya and is going to be placed into a scene ontop of a table. Any help with how you would tackle this kind of effect.
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