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Found 161 results

  1. 2d rbd collision

    HI.i want to reach this effect like this first gif shows. i have get this like second gif shows. i attach my sence file.hope you guys could give me some suggestion. thanks in advace. 2dBBD.hip b
  2. particles disappear after colliding

    Hello guys, I'm trying to build a simulation of blood through a vein. The setup is simple, a vein (tunnel) with particles moving through. They collide with the vein and themselves. I then use this sim to copy objects on the particles. The problem is each time a particle collide, it disappears... And I haven't setup the collision response to die... How could I fix this? Thank you... PS: I want to use different models for the blood so that is why there are several objects. Alain bloodflow_sim_debug_001.hiplc
  3. Hello all!, I am trying to create two different flip sims, which should collide with each other. Sim A is a flat tank, with a suction force and some vortex force. Sim B is a simple sphere emitting fluid. I want Sim B fluid to collide with Sim A fluid. Problem is if I do these inside one DOP network, Sim B inherits all the forces attached to Sim A, I am trying to prevent that. Maybe I'm overcomplicating this whole thing. Any ideas on how I can get them to collide with each other? Please refer to the attached hip file. Thank you all for your time. TwistForce.hipnc
  4. Hi guys. In a smoke simulation, I want to use a thin deforming geometry (a sheet) as the collision object, but instead of creating a Volume, I want to use "Point Velocity For Collisions". Is it possible? Thanks for helping. Smoke_CollisionPoints.hip
  5. I'm trying to create an animation of a ship rising out of the water and simulate the water on it. But the animation is so fast that sails and thin ropes are not recognized as collisions. Perhaps raising the substep is a good idea, but is there any other way? Ideally, the collision should be as clean as this
  6. Hi everyone! I'm struggling to get rid of those sharp voxels in the sim. I have a pyro solver, and I have tried increasing a lot the res in the Volume Object, Volume Rasterize Attrib, Points from Volume, increasing substeps, also the collider has a very decent mesh and it's also subdivided. I also tried using the collision object as a proxy vdb, and also using it as a collision volume inside the pyro solver. It's been very frustrating. I also found other posts with the same question, but still without any luck after all I have tried. I know the collision object may be causing all of this voxelization, but I keep on increasing the res, and I'm still getting the same results. Any help on this will be much appreciated! Thanks untitled6.mp4
  7. Hi there, I'm trying to understand Dopnet a bit more in depth and try to understand a bit better how you can transfer data from one object and use it in another. While playing a bit around I ran into a problem where I don't understand why this isn't working. I created a simple particle setup, and after a hit of a particle, a sphere is created into another object (called 'col_gen'). What I try to do is using these spheres in the next frame as a collision for the particles again. But somehow I can't get it get to work. Simple as that, right? What I did try is using the path "../:col_gen/Geometry" in the soppath of the static object. That doesn't do anything. So I tried to reference the geometry into an sopGeo node, and apply that data onto the staticobject. But that doesn't work neither. Question 1 is: Why doesn't this work like this? And question 2 is: How would you solve this problem? Cheers, Sander (The hipfile is hidden underneath the screengrab) generateCollision.hip
  8. Hi, I wonder if it is possible to trigger an animation on an event. Let's say I have a sphere, I simulate it falling on the ground just using a Dopnet and a ground plane as a static object. And let's say I want to play an animation each time the sphere touch the ground, like waves on some water. How can I do it ? I've heard of RBD Impact Analysis, but I can't find how to use the generated points for something like it ? Can someone help me ? And can I have an example file ? I link an example of wave that I want to trigger when the sphere touch the ground Sound_Wave_v001.hip
  9. Heightfield particle collision?

    Hi, I'm extremely new to Houdini and I'm trying to create sand winds like in here: My approach is to create particles (sand grains) that spawn on the heightfield, before being blown by a wind simulation or something (or instead of individual grains, just a smoke simulation) What I have so far is a Procedural desert heightfield. I followed a tutorial to set up a smoke simulation that advects to a pyro,, but I'm struggling with setting up collisions and figuring out how to spawn the smoke/sand procedurally on the heightfield. My pyro sim: My heightfield: Any help would be much appreciated! I can elaborate on any part so I can get advice better.
  10. Hello, i need a little help : I have a moving object with a scatter on it to create hair from these points. Theses hairs are stick with "pin points" and "match animation". And I would like to have hair collision with the object. But if I put this object on the collision input, there is a kind of artefact to these roots points. So what could be the solution to avoid this problem that is probably coming from pining AND colliding at the same time. I'd like to keep the pin system (no "attach to geometry"). Any idear ? Thanks
  11. I am simulating a beer overflow and somehow I can't get all the particles to slide down the collision geometry, which creates artifacts when meshing the simulation. Friction is set to 0 for both the flip object and staticObject (not animated), stickOnCollision on the flipSolver/volumeMotion is off and I have also set collision detection to none under the flipSolver/ParticleMotion Any ideas of what to try? Thank you (All the blue particles on the side of the pint don't move much towards the end of the sim)
  12. RBD collision Geometry

    Hi Everyone! I have a problem with collision geometry in the rigidbodysolver not moving. I have animated geometry I am plugging into the rigidbodysolver for collisions however I am finding it is remains static when I run the sim. The Initial Object Type is set to 'Animated Static' (although I have tried the others) Does anyone have any suggestions to get this collision geo moving again? Thanks sooooo much!
  13. Hi, Anyone know how to create this effects with the new pyro solver (geometry node)? On the static Object you had to click on "invert sign" but I can't find that on the new solver I just started Houdini sorry if my question may seem stupid Thanks all
  14. Hi guys, I am learning crowd simulation at the moment, which is suoer fun. With the premade Mocap Bipeds, all works fantastic. But when I create an agent out of an FBX from Mixamo, it gets super weird. When I try to set up everything for the ragdoll, the collision layer shows me that bones are missing. Why is that? Did you ever experience that? Also the question? To I always have to set up the joints from scratch? Is there no autmatic mode that kind of defines the moving angles? Thank you so much!! Patrick
  15. Hey there! I'm trying to fill a fractured box with water and make the water come out when walls of the box start breaking. The thing is that the collision works when the box hasn't been fractured yet but once one of the walls of the box starts fracturing, the particles start to clip through the box until they completely disappear. The box has thickness, I'm using a deformed static object with a vdb of the rbd fracture. The sim also have sub-steps. I uploaded the hip file, just in case someone wants to take a look at it. Thanks in advance guys! Flip_Collision.hip
  16. Hi, I have a problem with my flip bucket fluid sim. I made my bucket really big to not have to deal with to much sub steps.... but it still go through the mesh. Im using volume collision vdb (filled interior) move particles outside of collisions... is there something else I forgot? the bucket isnt going that fast but already gets inside the geometry thnx in advance
  17. Hello, This is my first ever post here. Usually I try to fix things by myself since it helps me learn, but I've been having this problem for almost 2 weeks now and it's driving me insane. I have modelled a storage shelf and placed buckets on it. The shelf gets hit by a ball and all the buckets fall on the ground. Some of the buckets have paint in them which is supposed to stay inside until the lids open. I have simulated the buckets falling and I have cached the simulation. I'm currently testing the fluid sim with only one bucket and the problem I'm having is that the fluid collides with the bucket just fine when it gets created, but when the animation of the bucket starts, the fluid just stays in its place as if the bucket never moved. Once the bucket falls out of place, the fluid also just falls down completely ignoring the bucket's movement. I have checked my collision geometries and they all look fine and follow the animation. I am using volume collisions, I have tried filling their interiors, extruding the collision geometry by a lot, increased the substeps, resizing the fluid geo and every time I get the same result. So I don't think it's a problem with the collision geometry itself, but more with how the fluid reacts to the animation of the static object. It almost looks like as if it's colliding with a bucket with no animation, which suddenly disappears. I am pretty sure the solution is something simple that I have failed to notice but I can't figure out what it is for the life of me. Any help would be greatly appreciated. Thank you.
  18. Hey guys. am recently decide to use houdini as a 3D package and i have an issue in a rigid body simulation. The problem is: i have a chain ring that should drop on the floor and after dropping all ring chains should interact with each other. at this moment when i drop chain ring, all chain parts just dropSide Effects Houdini 2021.02.26 - 00.18.55.01.mp4Side Effects Houdini 2021.02.26 - 00.18.55.01.mp4Side Effects Houdini 2021.02.26 - 00.18.55.01.mp4Side Effects Houdini 2021.02.26 - 00.18.55.01.mp4 and don't interact with each other, they interact only with floor is that possible to make all chain parts collision object? Side_Effects_Houdini_2021_02.26_-_00_22.09_02.mp4
  19. Hello everyone, setup is simple. I have 2 spheres and 1 ground. I set rbd configure to not collide spheres with ground. It works. BUT when I glue ground and sphere, rbd configure does not work! It must be bug or something, does not make sense? Question 2 is: How can I NOT collide between (big sphere - ground) AND (small sphere - big sphere - ground) ? collision and glue issue.hip
  20. Fluids - help!

    Hi team! I have followed a good tutorial on Youtube as I was having issues with keeping fluid in a container, this tutorial also shows how to do bubbles in the water ( Tutorial here ) When the bubbles go through the water there is a loss of fluid and I have been playing around a lot trying to figure out how to prevent the loss, when the collision objects aren't connected there is no loss in the amount of fluid but when I connect the Collison object there is a loss of fluid and I cant figure out how to stop that. I was wondering if anyone else happened to know? Its just bothering me and I wanted to know the answer. Cheers! Hottub.hipnc
  21. FLIP Collision with Alembic.

    Hi all, I've been combing the forums trying to get some fluid to stay in this fairly fast moving alembic animation which I think I've converted to proper polygons. I'm wondering how to make the fluid stick with the alembic container (martini glass) while still maintaining some sort of fluidity. As of right now it ghosts through my collision vdb on a faster move. I've tried fiddling with a number of properties like the resolution of the collider VDB / particle scale / particle separation / seeding / attribute transfers , but I fear I've just checked something I shouldn't have somewhere along the way. Excuse my novice ways and feel free to school me on better workflows. Any advice or solutions much appreciated. Thanks in advance. Flip_test.zip
  22. Vellum Collision

    Hello, I have some issue with my flowers colliding with my geo, they are interacting very weirdly with the geo, do you have any clue on what could help? Ps: When i did a test with less flower, the collision was good but with all the flowers, its like the geo repulse the flower making the flower's mesh explode. So, because it worked with less flower i tried to just up the substeps and the collision passes but nothing seems to do the trick. TEST_VELLUM_005.avi
  23. Object pop collision

    Hi I'm working on a test with arrows soothing on object, a very basic copy to point with particles Right after the arrows emit the object they are not falling not in a natural way they are "standing" attaching image and the scene, hoping for some help in this thank you Arrows_Test_01.hipnc
  24. Hello guys, So I have been trying to make a cloth collide with an animation sequence that is changing topology. I started with vellum and I hit a wall. Apparently, Vellum doesn't handle collisions with changing topology stuff. So I need to find a solution around this. My animation sequence is converted into a VDB and what else beside vellum can I use to handle the cloth? Any other ideas? Tx
  25. Hi everyone, I have a persistent problem with flip simulations. I have a guided ocean layer sim with a flip surface and a boat sailing (static object in the simulation DOP). The problem being that the inside of the collision boat is filled with particles every frame because of reseeding. I already have "Kill inside collision" checked in the Ocean source node and I don't want to turn off reseeding. Is there anything that can I do to avoid the reseeding inside the collision vdb? Am I missing something in the workflow?
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