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Found 39 results

  1. Constraint RBD to Cloth (or Grains)

    Hello guys, How can I attach a rigid body object to a piece of cloth? I'm a bit lost on this. I tried cloth and also pbd with no success, now I have no idea on what i should try. There's a file attached (using grains). It's a starting point if anyone can give it a try. Cheers - Alvaro rbd.to.grains.v1a.hiplc
  2. Granular Sheet - Moving Pin Constraints

    Hey everyone, after unsuccessfully scouring the web and the two big Houdini forums I finally brought myself to asking directly. I'm currently trying to animate a sheet of cloth using a granular sheet since the FEM approach is just excruciatingly slow. I've found three methods for pinning parts of the granular sheet in position (@stuck, @mass = 0, @targetP) but I wasn't able to find a use either of these methods for an animated pin constraint. I'm obviously still not really proficient in Houdini since this problem has me completely stumped. So if any of you lovely people would point me in the right direction, I'd be immensely grateful. Thanks in advance! *edit: After searching some more, I came across this thread: While the file attached to the thread works when I play it, when I try to copy that setup into my scene, it just refuses to work, even though the @targetP gets updated. Obviously, I'm doing something wrong but even comparing the node settings side by side I can't for the life of me figure out what that something is. *edit #2: Okay, I finally figured it out. I didn't realize that the sop solver node is empty by default and you have to create the sop structure to update every frame by yourself. Now that I've figured that out it is perfectly reasonable, I just didn't think of that for quite some time. dia3_dmo_001_010_cgfx_setup_v003_pj_stripped.hip
  3. Freezing Attributes

    Hi Odforce! Im working on a little project using the object packing technique from Ben Watts Design's tutorial. I've got an attribute VOP using turbulent noise to drive the pscale attribute. Im then reading this into a popnet through a sop solver, but when the particles move they adopt the pscale of the underlying position of the noise. I believe this issue is related to the sop solver reading the new pscale in every frame but im unsure how to essentially freeze this attribute. I want the points to be born, adopt the pscale based on the location it spawns on, then for the pscale attribute to remain frozen for the rest of the simulation, how do i go about setting this up? I have attached the scene file here. CardGrowth.hip
  4. Field-O-Spheres

    This is the first thing I've done that I'm legitimately proud of. Simple, but a lot of fun! Took inspiration from Brandon Woelfel and a lot of the scenes in Pop's Dinner in Riverdale. Any feedback would be great
  5. Grains cloth - bend resistance

    Using grains for cloth is extremely fast but since it’s not a fully fledged cloth solver it lacks control for creating realistic cloth sims. There is only really self collision and a basic stretch resistance through explicit constraints (through to avoid stretch you have to put constraint iterations very high..), but it doesn’t seem like there’s any concept of bend resistance in the explicit constraints. Does anyone know of a way of creating bend resistance or faking it somehow?
  6. Granular Sheet - Pin Constraint

    Hey guys, I'm testing some cloth simulation using PBD but couldn't find a way to constraint some areas of it. I don't want to constraint it to another object, just want to make those particles to be "frozen". Can someone give me some ideas about this? Thank you /Alvaro
  7. Sand Simulation

    Hi! I'm a student at NAD in Montreal and I'm trying to learn Houdini. I have a project in which I need to simulate sand on top of a falling rocks RBD simulation, which is on top of a FEM sim. (The FEM is the deforming ground) So I cached every collision objects with the CollisionSource node (with 4 substeps to match de grain solver). Now, if I simulate the sand, it explode on random frames. (see flipbook here: password: sandsim This is my second attempt and it still explode (at fist I used 10 substeps) Does somebody have any ideas on what could be the issue? Thanks MountainGrowth_47.hipnc
  8. Hey magicians, Been fighting with this pile setup for a couple of days, I need to make a candy pile, I'm using grains but when I replace the geo there are some artifacts like the geo is inside the particle and leaves weird holes, anyone knows how this can be fixed? It need to be the more realistic way possible @f1480187 would love to hear your thoughts sensei Thanks pile3.hip
  9. Grains - Disable Constraint Averaging

    I posted this on the SideFX forum but haven't had any response so I thought i'd try my luck here: I'm getting some unbalanced forces when using grains, its the same problem as described in the grains masterclass around 32:50. As Jeff says the solution is to disable constraint averaging and then insure all the internal forces add up to 1. I've done this but I still have an imbalance.. I wanted to check which forces are meant to add up to 1, in the video it implies that Internal Collisions + Clumping + Explicit Constraints = 1. However in the help document it mentions that Friction with Particles should be included as well. So should I set Friction with Particles, Internal Collisions, Clumping and Explicit Constraints to 0.25? (
  10. I'm having a play with grains for making simple ropes and cables, and the problem I'm having is that they just bounce and stretch waaaaaaaaay to much! The rest length attribute on each prim is the exact length of those prims (and therefore the sum of all the rest lengths is the length of the rope) and the substeps on the pop solver are set to 10. What I want to do is simply reduce the amount that the rope stretches and bounces. Up till now, the only real solution I've found (and seen other people do), is mess around with forces and substeps (in one case I turned them up to 1000), but doing it that way just feels so convoluted and still doesn't let me tune in the exact results that I want. I've also been playing around with attributes as well as having a dig around in the solver itself to see if there is anyway to modify it, but alas I have come up with nothing (I'm struggling to figure out whats going on the grains node). I guess what I'm wanting to do is find a way to control how the rope moves/looks (ie the stretching and bounciness) with physical properties instead of forces. In other words, instead of having to use a pop drags and all that, just get the rope to not be so susceptible to stretching in the first place. Does anyone have any ideas?
  11. Rigid Object using Grains (styrofoam)

    hey guys, is there a way to make a granular solid to be very rigid? Not cloth like. I have to simulate a detailed styrofoam breaking and it would be perfect if I could work with grains. Thx, Alvaro
  12. Partial collision detection

    hey, little problem here. I have a piece of cloth made out of grains. Its colliding with an object. Here I use a collision detection in combination with a collision behaviour. The collision detection shall only detect a few polygons of the whole object to stop the motion there. Referencint the polys in dops. Its giving me a correct collision guide but during the sim it keeps ignoring it. Insteat it freezes the grains along the whole 'main collision object'. So that are the areas to collide with, just a few squares.
  13. hey guys so this one is thumping my head i have a popnet with some grains... its working well. now i want to simply cache out this simulation to disk, then bring it to another hou file. But what is the best way to go about that? I'm just lost here. i can cache it out a .bgeo sequence and then fetch it in with file read node into a blank hou scene but the grains have lost their spherical look and the ramp colour too ? I cant for the life of me suss out how to plug this into a new popnet scene anyone with any advice much appreciated losing my head here ant
  14. I've found that with finite elements(or cloth or wire) you can create multiple iteration of an geometry in a sim with the Creation Frame parameter. using floor($F/10)*10+1 see attachment I'm wondering if there is a way to do this with grain solids. I can add multiple pop source at the beginning of the sim but i would like to create a new Pop solid every 10 frames the way I can with FEM. I tried animating the impulse activate on the pop source and tried changing the activation parameter on the pop grains node. I'm guessing this is not really possible without multiple pop source nodes and point deform nodes. But maybe someone here has a solution. thanks
  15. Grains morph target geometry

    Hey, how would you go about transporming the target geo in something different without having the grain solver go crazy? So not just a transform, shuld be a different kind of geo. Also with intact constraints.
  16. hey chaps so pretty simple one... made a ball, applied granular solid from the shelf. now i have a simple knife tool that drops on it cleaving it in two. really quick... takes mins to setup in houdini - love it. So heres my questions... i have the embedded mesh but when it slices its still one shape - how can i slice it into two? (the other thing i have is the grains which i converted into vdb then back to polys) for both/either of these results how can i transfer an inner colour into the geo? in my naivety i object merged the knife into my vdb then applied attribute transfer to transfer colour - but the colour wont stick as the two halves drop away from the knife. anyone got any cool ideas? ta ant
  17. two objects in a granular solid sim

    I'm trying to set up two pig heads in a grain sim that collide together. an extension of the grainular solid example in Jeff Lait's h15 grains masterclass. in stead of one pig head i want to wire in two. I've set up two pig heads (skipping the bone group part for now) see attached file. Jeff shows how to override the P and v with from an animated version of the geo with a wragle. I've set the dop net up the same way with two sources. however for some reason one of the P values apparently collapses to 0. if i switch the merge order it switches which source goes to 0. see attached file. I'm obviously missing something here. help would be appreciated. twosolidpigs.hiplc
  18. Grains_test_houdini_v0.1

  19. Hey, Super new to Houdini here. Trying to stray away from my comp education and go into FX instead. We just finished a group project and it's time for summer break so I want to go back and do FX for a couple of finished projects of other groups to get finished comped shots to build a FX reel. For this particular project I wanted to make a grain simulation for a group that had a hermit crab switching his shell on the ocean floor. The finished project contained just a mesh with a sand texture on it together with stock footage for some dust and smoke when the crab flips the new shell from the sand bottom. I have attached my super quick way of re-doing it by following mainly a tutorial about the grainsource/grainsolver adjusted to this scene. My further a long hip is not that much better off anyway and much messier with much trial and error. Main problems are; -The particles keep moving for such a long duration even though I have friction parameters set to 1. Maybe the sim just have to run much longer? -Size of particles to represent sand obviously has to be quite tiny so I'm a bit unsure if I will have to scale them down all that much and create a super thick layer that covers all the way down to the tip of the shells flip animation (at ~54F) that to me looks like I'll be in the millions. -Camera seems off. I was reading up about camera exporting from Maya and asked a former student at my school that has been at an internship working with Houdini that said Null scaled to .001 is fine but it doesn't match the final shot. I will also have to double check this with the group that provided me with the assets. Still nice to get clarification. -Underwater gravity for the stones. I assume transfering Cd to the particles getting hit by the shell and then add a POP Force group that lowers the gravity specifically for those particles? -Maybe not such a big issue but particles clipping on the ground plane. -I also don't seem to be able to give the grains a shader/material like in the tutorial I watched. I have no idea what I'm doing wrong here. Just adding a dirt slaps it in /mat and gives it to everything except my particles. Although that works when doing the dop import afterwards when everything else is removed anyway. I have attached the hip file a long with the assets I have received from the group. cstSand.zip
  20. Combining sim mesh with non-sim

    Hey friends, I have had a problem the last few months that I have not solved, so I figured I might post here for help. I am doing foot step simulation for a walking animated character. The character is supposed to be walking in snow. So I used the grain solver, and got some pretty awesome results. So I converted my grain simulation and exported an alembic cache of the ground mesh. Here is the problem: Because the ground is so huge, I only simmed a small segment of the ground mesh. How do I effectively combine my simmed ground with the non-simmed ground mesh? Something to keep in mind is the topology on my simmed mesh is much higher because more detail is needed for the foot prints. Any suggestions? (sorry about dupe posts, I cant delete them.) Thanks
  21. Combining sim mesh with non-sim

    Hey friends, I have had a problem the last few months that I have not solved, so I figured I might post here for help. I am doing foot step simulation for a walking animated character. The character is supposed to be walking in snow. So I used the grain solver, and got some pretty awesome results. So I converted my grain simulation and exported an alembic cache of the ground mesh. Here is the problem: Because the ground is so huge, I only simmed a small segment of the ground mesh. How do I effectively combine my simmed ground with the non-simmed ground mesh? Something to keep in mind is the topology on my simmed mesh is much higher because more detail is needed for the foot prints. Any suggestions? Thanks
  22. Constraint Grains to Animation (targetP ?)

    Hey guys, how can I use this target pins option? I have an animation in sops and I need the grains to be constranited to that animation. I guess the targetP attribute shouldn't come from Sops but I can't find a way to make it in Dops beased on that Sop animation. Any tips? Thx
  23. sand disintegration

    Hello, I'm trying to get a logo to dissolve/disintegrate into sand. Like it is made out of sand and something is eating out the outside shell and the sand is pouring out. In the attached file I was first trying to use a geometry and use attribute transfer to set the force of a popforce. as I would like to use in the future a more random/noisy pattern. I'm not exactly sure if my expression is wrong, if my whole set up is wrong. I tried to look around for tutorials or thread but couldn't find any. Any idea, suggestion or links would be greatly appreciated. thanks bil Sand_Desintegration01.hipnc
  24. HOUDINI SAND SIMULATIONS

    Hi all, I will be post all my sand simulations in this thread. All critics and suggestions are welcome.
  25. hey guys i'm properly having my chuddies rubbed here. I've got a scene where i have a simple walk cycle character. I'm trying to get him to crumble away but for the life of me i cant get the bloody thing working!!! I've tried putting a colour on the character, then a group with a few red points. then i'm using a small wrangle code from a yt tutorial to 'infect' outwards from those red points. I've tried this in the sop context and in the sop solver within dops and its biting my ass big time now. I cant understand what i'm not doing right. in the same scene i'm also doing the same trick with a sop solver and a pointvop for noise/colour this works ok but the character moves 'through' the 3d noise and those grains fall away - but i cant suss out how to lock that 3d noise down so it moves with the character as opposed to him sliding through it :/ can anyone help here? I'm at my wits end with sop solvers - i've a feeling i'm close but its that final tweak just to get it to work thats eluding me I've included a scene with the two examples/fails and my walk cycle alembic for you cheers ant GrainWalk4_using_infect_wrangle.zip
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