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Found 29 results

  1. 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.
  2. 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
  3. 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
  4. 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.
  5. 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
  6. 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
  7. Grains_test_houdini_v0.1

  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. HOUDINI SAND SIMULATIONS

    Hi all, I will be post all my sand simulations in this thread. All critics and suggestions are welcome.
  14. 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
  15. Granular Sheet - Can't Rip the Mesh

    Does anyone know's how to solve it? It must be simple but I just can't find a solution anywhere :/ Grains in Dop: Mesh in Sop: Thx again, Alvaro granular sheet - ripping it.rar
  16. Granular Sheet - Can't Rip the Mesh

    Does anyone know's how to solve it? It must be simple but I just can't find a solution anywhere :/ Grains in Dop: Mesh in Sop: Thx again, Alvaro
  17. Good evening everyone! I'm trying to attatch my pop grains to a deforming geometry. I've tried seeing everything related to pop particles on the forums but nothing worked. Thanks for those who help !
  18. 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
  19. Animated granular sheed

    Hi, I was searching for a better way to simulate cloth like sails or flags and ended up using the grain solver. It gives me some pretty nice results compared to FEM. I also can pin some points down with a mass attribute but can't pin the stuff to an animated object. Any idea how to do this?
  20. Simulation Strategies

    Hello! I was wondering if some of you had a strategy to render high resolution simulations. For exemple, to render a high resolution smoke, can you render at a low resolution multiple times? Thank you!
  21. hi everyone i have a small issue here with my sand grains (wet grains) - i'm trying to get my mesh to collide with them but they seem to be jumping about a fair bit as the character moves. I'm not sure what i can do to adjust this jumping about does anyone have any ideas? playblast below to show you what i mean. I cant share the scene file right now sorry but the jumping of particles is quite noticeable here ip.mp4
  22. Hi, I am not sure what causes this weird render problem. I am trying to make the sphere deform the snow as it moves along. I started off with the sandbox shelf tool. I converted that using the VDB from particles (you can see in the photo below). Then I converted the vdb from particles to a polygon mesh using the VDB convert node. You can see the mesh in the photo. How come when I render it you see all the individual spheres? it clearly does not match the topology from the mesh. Not sure if this affects anything, but I am using the Non Commercial Addition. Thanks in Advance
  23. okay so i've got a little issue here... I have FINALLY (After 30 hours of twiddling) got a really nice fairly stable sand grains anim going that interacts nicely with my char. so i've got my node network which is a basic off the shelf grains upres... i'm trying to wrap my head around whats happening in setseed_adjust_scale attribute wrangle node but i cant suss it out anyway what i want to do is vary the scale of my upres particles making some bigger and some smaller. so in my head i drop in a new attribute wrangle node (circled red in the pic) and i add the following: float @pscale = 1; @pscale = rand (0.002, 0.006); and BLAM! my pc fan after 30 seconds nearly ran out the window screaming!!!!! Its done this twice now and just locks up hou and the pc! so i'm properly stuck here - i cant figure out how to vary the scale of those upres particles - they are all the same size Anyone got any ideas on how to adjust this? ta ant
  24. pop grains using non sphere shapes

    Hi all, i want to use grains but not use the basic sphere. i tried to get the RDB grains working but when i replace the sphere it doesn't take the new shape into account. using shapes like stones, or rice, or even beans. any why to to this? or should i just stick with RDB, instead? thanks A
  25. pop grains accumulation

    Hi, I'm trying to create a sort of sand-in-hourglass effect, where piles of sand accumulate over time from a steady stream. I'm using the POP Grains DOP to try to accomplish this, but the particles don't seem to want to stack. I'm relatively new with this particular solver so I'm not entirely sure what the approach is for accumulating piles like this. Can anyone point me in the right direction? Thanks!
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