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Found 16 results

  1. What's the best way to simulate dynamics with just 2D shapes? Is it possible to use any of the existing solvers to simulate rigid bodies, but also flexible curve/polygonal shapes that respect line to line collisions ? I've tried using the wire and the grain solver (with rest length on a network of lines that connect the points), but the collisions only happen on the point level, resulting in penetrations between shapes. Is there anything else I should look into, or a working example I can take a look? thanks a lot georgios
  2. Hello I have a very strange situation where the grain particles suddenly explode along a line!.instead of volume collision I used "use surface collision" for collision detection for the body of the butterfly .as you can see there is no problem, but right the next frame the particles explode in such a strange way that I couldn't figure out why. I checked the setting for dozens of times... I found nothing wrong.I have other simulation with the same setting, It is worse.please let me know If something's wrong. thank you in advance
  3. 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
  4. Hello I am trying to make a voronoi fractured object into grain soft body. I split the object with voronoi fracure, and use for loop to create grains for each piece. On the dop level all looks great - all voronoi pieces are separate and bounce around the way I wished. The problem is when simulated mesh is read back and fed into point deform sop. The original mesh is not acting as separate objects. Is there an easy to correct this? Also, is there a way to create a glue constrain for grain sims? voronoi soft body.hiplc
  5. 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
  6. Hey! I have a question about slowing down the motion of pop grains. Trying to find a setting or node that will cause the grains to lose velocity quickly, because they don't get to their rest state fast enough. In maya, I would use damp or conserve. Conserve changes how much force a particle can retain each frame. Turning the conserve down would cause the particle to lose much of the velocity from the previous frame. How can I do this with POP grains in houdini? Thanks in advance.
  7. So I've been trying to get the grain solver to use animated geometry as an emitter but I can't get it to work. I'm trying to create a sandman effect like this http://forums.odforce.net/topic/11658-flip-fluid-sand-girl/?page=1 but I cant get it to work since the project is quite outdated. The problem is that the creation frame occurs on frame 1, and If I change it, to say 1-10, it wont give me the effect I'm looking for, I moved from 3dsmax to houdini 1 month ago so be simple in your questions if you can
  8. As nobody answered my previous post (no hard feelings ), here I am again. I have made some progress with sand/grain but I'm still not sure of the process. In this new file I'm trying to have the sand to gradually blow away . I'm using a PopForce to move my particles and I'm controlling the v@Force Attribute with a voppop. I'm using a ramp based on Y and a turbulence noise to set the @force value as I would like the sand to start blowing randomly from the top and slowly go down the pile of sand. But I have 2 problems. 1- because the noise and the ramp are based on position, the particles enter and exit the noise/value 2- the noise is fading to quickly, I think I need to add a fit node to compensate.. but I can't figure it out. Here is my ramp/noise test (on a volume). PS: my previous post was about sand disintegration. and I attached a Hip of my scene. Please Help me out! sandtest_forceRandom.hiplc
  9. Hi, I try to recreate more or less the same as sidefx presented in the demo video for grains. There a lot of bacon slices popp up and fall down. Unfortunately I have no idea how I can emit these slices with grains. Would be great if anyone can give me a hint where to start.
  10. Hi everyone, I am trying to use a grain simulation to create a sticky gum effect. (like this video) but I have a problem with the meshing. To create a skin out of my grain I first convert my grain to vdb (with vdb from particlesfluid) and then I use convertvdb with the polygon polygon option to convert this to a polygon “skin”. Everything looks perfect in the viewport but when I try to render, it is inflated at rendertime, ie: it’s not a perfect match with what I see in the viewport. If instead of grains, I use a sphere that I convert to vdb volume and then back to poly with the same convertvdb node with the polygon option I don’t get this volume increase at rendertime. See yourself: Is this a bug? Do you know any workaround I could get mantra to render the same result as I see in the viewport when using grain as a source? I saw this thread where someone talk about creating properties in a shader to get to render vdb isosurface directly without converting to poly: https://www.sidefx.com/forum/topic/29678/ But I still have to investigate that one, looks a bit complicated. As another workaround I could render my sim correctly by writing the vdb to disk and loading it in max to render with vray and it rendered correctly. But still I would like to know why mantra can't do it. thanks
  11. Hello everyone ! I'm trying to get an object impact sand. To achieve this kind of effect I planned to create a setup based on this great idea: https://vimeo.com/155198661 Here is what I have so far: Unfortunately I lack the maths to go further. What I need is to spread my velocity vectors outward from the collision mesh and also to remove any vectors that are "BEHIND" the motion. I was wondering if there was a way to ramp down the density using a volume VOP and the BB attribute but no luck so far, or find a way to emit more grain at the front, avoid a constant emission within the volume. Do you guys have any suggestions ? Cheers ! sand.avi collide_setup_01.hipnc
  12. Hello, I would like to know if that approach is possible using PDB and the new grain solver: 1. Create a Granular solid from a VDB animated mesh and make all the grains move acording to its deformation and position. 2. Break some of the constrains so that some particles will no longer follow the VDB mesh. Thank you!
  13. Hello, I posted this a few days ago on the primary Houdini forum, but haven't gotten much traction with it, as it's a pretty strange bug. In short: I've animated the movement of a box, with grain pouring out of the box. Unfortunately, the grain doesn't leave the box cleanly: as it pours out, it creates a stair-step pattern on the bottom edge - one stairstep per frame - as if the box collision geometry isn't interpolating correctly during the subframe timeslot. Some notes: - Collision geometry is a single piece of geo that is translated inside Houdini via keyframes rather than an Alembic Cache or geometry sequence. - I added a time-blend node as recommended by jeff in the Houdini forum. - The "Re-evaluate SOPs to Interpolate Geometry" box in my static object node in my DOP network is checked. - Increased simulation substeps to 30 (The grain-stepping effect seems to generate one step per frame, so increasing the simulation substeps doesn't appear to have any effect. ) Despite all of that, the stair-stepping still occurs. Any thoughts would be appreciated! Thanks, Luke GrainStepping_02i.zip
  14. Hi all, new Indie user here, so be gentle! im trying to do a grain sim, and i have a complex animated collision object. i decided to cache out the collision volume to speed up sim times, as it spend a large proportion of the time "calculating SDF" i followed instructions i found online, and in the static object DOP i set the file mode to "write" and specified the filename as "collision.$f04.simdata" i then set the grain radius very high for a fast result, and ran through the sim. it saved out a series of .simdata files (22 meg each approx.) i then set the file mode to "read" so far so good. however, when i sim again, it -still- spends a similar amount of time "calculating SDF" and doesnt seem any faster.. what did i miss? many thanks for any advice, Robin.
  15. Hey Everyone, CG Workshop is currently enrolling for the Intro To Houdini 14 course. I will cover a variety of material and get into many technical low level concepts, such as the math, geometry, and trigonometry involved in gaining complete control over an effect. When it comes to making great FX, there aren't any push-­button solutions. This course helps to lay that groundwork to understand what is going on under the 'hood'. I will take you step-­by-­step through the construction using production techniques in Houdini, right from looking at the UI and procedural modeling in Week 1, and eventually on to particles, grains and fluids. We will cover methods that give complete control when you're procedurally fracturing geometry, creating dust and debris, dissolving effects, as well as procedural animation and modeling, to name a few. http://training.cgsociety.org/course/introduction-to-fx-using-houdini Check it out and let me know if you have any questions! Spencer
  16. Hi guys, this is my first post here in OdForce, and let me just begin by saying that it's an awsome community! I'm trying to do a soft body simulation of raspberries falling and hitting a surface, thought I'd give a shot to the new Solid Grain object, mainly for it's speed. Right now I have one raspberry falling and my problem now is to duplicate the object so it look it's raining fruit! I've already done this with RBD, FLIP object etc with success, but I can't seem to make it work with PBD. Anyone has any pointers on this? Thank you so much in advance! PS: attached a basic scene file with a sphere instead of the raspberry! fuit_rasp_pbd_example.hip