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Found 148 results

  1. 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
  2. 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
  3. 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
  4. 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.
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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?
  13. Hi! First post here. After months of lurking and picking up tips from other users topics I need more direct help. I'm quite new to Houdini and I hope you share some ideas. With given FBX meshes, I have to simulate a gate being rammed out from a wall. Chunks of portal around the gate are supposed to be pulled out with it, hit the ground and crumble into bricks while the rest collapses. Gate itself is animated with bones, not physics-driven. After many experiments, I couldn't achieve that two-step fracture (big pieces falling on impact and then crumbling). This is what I've already tried: 1. I've split all wall FBX into bricks using Voronoi fracture fed with array of points (four pieces total: the portal, left, right and top parts of the wall). 2. I've divided the portal into chunks by grouping fractured elements with separate glue constraints. 3. I've created set of constraints for each piece.). 4. I've constrained all parts of the portal to the animated gate. 5. I've imported gate and wall as RDB Packed Objects to a DOP and fed it to bullet solver. 6. I've set up constraints networks for each piece with SOP solvers connected. The idea was that the portal is connected to the gate by glue constraint with infinite strength (-1) and pulled that way out of the wall. After few frames the constraint is severed by deleting lines in SOP solver. Constraints for individual chunks remain until they are broken by impact with ground. Meanwhile the result is that: when portal-gate constraint is removed while the portal is still in the wall, it's being abruptly shot upward. It looks like the animation (which I can't alter) forces meshes to overlap, so they pop when it loses control over them. When the constraint is removed few frames later when the portal doesn't collide with anything, it gains such high acceleration already, that bricks spray all around as if it has been an explosion. I suspect that my pipeline my be noobish, but I couldn't find any resources on similar cases. Unfortunately I can't share screenshots nor files as they are part of a commission. I'll appreciate your help.
  14. Hello everyone, I'm trying to do a multiple explosion effect on a piece of geometry with a glass material and I have some issues with concave shapes. Since the object needs to be transparent I cannot use any kind of pre-fracturing, otherwise it would show. (picture 1 & 2) So I setup a DOP network with a SOP solver inside to fracture the geometry dynamically. (picture 3) It works fine and the explosions are happening as planned. But since the geometry is concave, a convex collision shape is automatically created around it. (picture 5) And this causes the pieces created from explosions to be pushed outside instantaneously (picture 6). So I've searched for ways to handle concave geometry and this is what I found: Use the "concave" option in the "rbd packed object" node. It works! (picture 7). But it is excruciatingly slow, and this chess piece is part of a larger simulation with other chess pieces with similar issues. So in the end it would be difficult to work with everything being so slow. Decompose the base geometry into convex shapes. With the "convex decomposition" SOP for example. Since it produces several pieces, I can't display the result directly as the object is transparent (same issue as picture 2). And since I fracture the geometry dynamically I don't see how I could replace the simulated geo with some display geo in the end. Maybe I'm missing something here, but I don't know how to replace proxy geometry with display geometry when the proxy geometry is dynamically fractured. The "compound" option in the "rbd packed object" node The description of this option looks promising in the documentation, but it specifies that you need to use a node to generate some data, and that node is deprecated... It is replaced by another option called "Create Convex Hull Per Set Of Connected Primitives". But as far as I understand, your input geometry needs to be made of several "pieces" for this option to be useful. Is there anything I missed here? A method for generating collision shapes that doesn't involve breaking your geometry into several components?
  15. POP particle collision/final resting

    OK... I think I've exhausted my button pushes and research. If anyone can give any pointers about getting my collisions/debris to actually appear to rest on the surface and/or interact with the moving model I would be very thankful. Currently, the `debris` appears to come to a final rest above the surface. I've included the scene and ref'd geo. quinniusMaximus_recog.zip
  16. Hi everyone, I have a simple sample scene here, having problem with the flip collisions. - I have a basic deforming sphere geometry that has a colliding liquid which works fine. -Problem part it i also have some liquid pouring on top of that deforming geometry (needs to collide the outer side of the sphere) but seem like there is a square bounding box around the collision (due to negative sdf) geo which gives me unproper collision outside. How can i have correct collisions for both inside and outside of the deforming mesh? thanks. Flip_InvertedCollision_Problem.hiplc
  17. RBD and its sleeping properties

    I set up a scene with crates that I want to get destroyed by a flip sim. figured out that I had to put a attribwrangle with i@bullet_sleeping = 1; so that RBD stays in place until the FLIP collides. The problem is now that with a little hit of flip to a group of crate the push activates all of them to break. I am a noob, but found that there is a threshold to control the amount of impact to activate the RBD. I just dont know which one of these it is and how to apply it to wrangler. bullet_angular_sleep_threshold bullet_ignore bullet_linear_sleep_threshold Documentation found here : https://www.sidefx.com/docs/houdini17.5/nodes/dop/rbdpackedobject.html Here is the original failed vid: https://www.dropbox.com/s/dl8ze5rv4vf6gse/Test.mp4?dl=0 Here is current failed test vid: https://www.dropbox.com/s/sa4sumxfqpqmdhq/Flud Test2.mp4?dl=0
  18. I'm looking for some guidance with an effect. I have a pyro simulation of some smoke hitting a floor and the collision is working fine. I want to take the collision information from the sim and pass it back to the floor geometry as a point attribute e.g. an attribute that is 0 when the sim starts but as soon as the smoke touches the floor the attribute changes to one. If anyone that could point me in the direction of how best to achieve this, I've tried to play around with the 'Gas Impact To Attribute' node and I could not work out how to properly wire it up. Thanks! SmokeCollision-01.hipnc
  19. Vellum Collision Problems

    Hello! I am trying to deepen my understansing of vellum by building the solver netowork myself. I have hit is very enfuriating sustuation were my character litterally walks out of her pants. When I use the sop based solver this dosn't happen. I am sure I am missing something but it seems most things I have tried are giving me the same result. I am using an almebic cache for the collider, and cloth geometry brought in from Marvelios Designer. I am using an collision source node to generate a vdb for collisions, and using a staticObject set to “Use Volume Collision” and “Volume Sample” for division Method. Here is what I am getting
  20. Hi, I would like to create an animation of blooming flower. I've created the basic setup, but I have a problem with intersecting petals. Does anyone have an idea how to get rid of those intersections without deleting whole petals? Thanks in advance for all the answers. flowertest.hiplc
  21. Hello guys, So ive been trying to test the difference between using a collision object or a collision source in pyro sims. I still cant grasp the difference between each other and when should I use one or the other. What do you think? pyro.mp4
  22. Select collision particles

    Hi, I have a geo diving in flip Problem: I like the ripples at the beginning, but I want to slow down the ripples that get too high Question: how can i select only the particles that collided with the geo? I want to add the particles that collided with the geo to the group and limit their speed or maybe add a drag force to the selected group. Is this approach correct or is there any other way to keep the low ripples and slow down the fast ones? Thanks IMG_6198.MP4 Also online preview https://yadi.sk/i/yxXCQ8Yghz11Jg
  23. Hi everyone, did a pyro sim along with a collision object. When I up the density from 1 to 4 in the pyro shader, the voxels are getting visible (attached an image to the post showing the issue). Is there any way to prevent that or soften the voxels on the outside in a post process or something? Cheers, Christian
  24. Vellum Cloth Collision

    Hi everybody. I have a cloth rack with hangers and clothes on it. The rack moves along the path. I simulated and cached the hangers moving with the rack. Then I modeled and draped the clothes on a static hanger and copied the draped clothes to each hanger to simulate the clothes on the moving hangers. I thought instead of using static deformed object it is better to use RBD fractured object (making it inactive) with point position, translating the transform of the hangers, so it would not load the collision geometry every frame. To help the vellum follow the animation of the hangers I also soft pinned with match animation those parts of clothes that "touch" the hangers. The problem is, after a couple of frames, the clothes start to penetrate the hangers. Increasing the substeps (tested with 10 and 20 substeps), collision passes, polish, post collision passes doesn't solve the problem. So generally I have 2 questions, first is: which collision type is used in vellum simulations: Bullet or Volume? And second: any thoughts on how can i solve my problem? Loading hangers through static deformed objects also dramatically increases calculation time.. Or is it the only option for vellum? Thanks in advance!
  25. Hi everyone, I have a simple fracture simulation that I would like to use as collision geo in a vellum sim. However as vellum is particle based, and the collision geo is very low poly, I need to somehow increase the geo subdivisions for the fracture sim geo. I've looked at using the subdivide node, but this doesn't seem to work. I'm hoping this is a simple one and I'm just not aware of the right node to drop in! Thanks in advance! Glass.hiplc
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