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Found 85 results

  1. How does constraints work?

    When we are using constraints does the bullet compare the position of the constraints every frame with the world space position of the constraints in the first frame? Specially in the case of hard constraints and soft constraints to make them return to its original position based on stiffness value. What if the position of my constraints are changing per frame will it compare every frame or just to the first frame only?
  2. The constraints seem to be broken in Houdini 18.0.532. I followed the regular workflow for building constraints for a regular rdb simulation. But they don't seem to make it to the DOP network. There are no errors, but the constraints don't work (They don't appear in the dopnet). Can someone please confirm this? Thank you.
  3. Scaling down soft constraints

    Hey guys, I have a mix of glue and soft constraints which switches to soft constraints once the glue breaks, I want to scale down each constraint primitives, I am using a facet node to make unique points then a primitive sop to scale them down (everything before the sim) but then inside the sim once the constraints switch to soft it goes back to its original length (i have restlength 0). I even added a sop solver and tried making the scale to 0 using primitive sop but it's not working either. Can anyone help a bit?
  4. Is there a way to "smooth" a look at constraint, so it's a little less frame-by-frame precise and a bit more drifty? Thanks!
  5. Hi all, Does anyone have a workflow for attaching fractured geometry of an animated alembic, to the animated alembic itself? For example, a moving vehicle that's animated to collide with something and continue moving (the whole sequence of how the vehicle moves is hand animated), so only some parts are fractured for the rbd simulation (like half of a plane's wing, some window glass, parts of the nose fly off), but the rest of the parts that aren't affected are animated via the alembic to continue moving. I've tried attaching the constraints to the timeshifted alembic geo, then use transform pieces for animating the static objects, but i think my constraints are invulnerable right now? They don't break and no forces can affect them, even if i set my strength values to 1. I wish i could send an example file but i'm troubleshooting for work, so i can't actually do so. Any help or hints would be greatly appreciated, and thank you anyone for taking the time to read.
  6. Hey, I have a brain scratcher that I need help with. I have animated a jacket with vellum using cloth constraints and then cached it out. Now I have the toggles and zipper to add I can use vellum as it doesn't do anything with hard bodies so how can I constraint them to the geo? Any help would be great! Thanks Andy
  7. Hi all, I am quite new to Houdini so please excuse me if the answer is super simple. Been trying to learn how to rig a little lately with small industrial robots (3DOF) FK systems are simple enough to implement however, I want to create a simple 3 bone IK rig with each bone only given a single rotational axis of freedom. i.e. bone1 one can only rotate around x axis, bone2 - y axis, bone3 - z axis to reach a single goal. Is this possible? I hope this can lead me down the path to creating "simple" IK rigs for Industrial robots with 6DOF (but I am dreaming here). I saw Maya already has a plugin for this sorta thing called Mimic, open source and quite elegantly done > https://www.mimicformaya.com/ I was wondering if its possible to build similar functionality within Houdini.
  8. hello good day yawll my test is all about a table will get slowly destroy by using sphere as a glue removal constraint help of attribute transfer but its not working my file is here below anyone plse help me out test.hip
  9. Hey all, it's first post here and new to Houdini so I appologise if this isnt the easiest to follow. I have been trying to create a robust system for controlling vornoi fracture points, their glue strength and a way of manually breaking constraints between points. Ive been following some tutorials piecing together relevant bits from each to try and achieve this. My current issue Im facing is that once I play the simulation and the constraints start breaking they start flickering back on and glueing parts of the object which have already been broken. From my undertanding I think the manual breaking of constraints which is conflicting with the remove_broken SOP solver within DOPs, but I can't figure out how to get them both to work together. Any help would be greatly appreciated as I've hit a brick wall with this. Ive provided my scene file - I hope it's all easy to undertand. Thanks. Fracture_v001_notworking.hiplc
  10. Hey guys, I am currently working with bullet soft constraints and am using the angle, distance, force and torque attributes to determine when to break the soft constraints. I am facing an issue through where a lot of the soft constraints attributes are all 0 and they all stay 0 throughout the sim. Usually they will initialize and update even if the constraint stays relatively still so I don't this think is normal behavior. I've been trying to get it working for the past few days as well as googling around but my google-fu and troubleshooting efforts have turned up very little, so I now turn to you guys. The weird thing is that some of the constraints work just fine, but most of them seem to not work properly. I've added my file if someone wants to donate their time to have a look at it. The sim can be found in /obj/Primary_RBD_Sim/dopnet1. The constraints responsible for most of the movement is the "brick-mortar" constraints, so I usually add that to the geo spreadsheet's group field. I have tiried to lock the heaviest cooking nodes (hence the file size), but if the scene cook's a lot when opening or if the geo is missing, have a look at the "Lock"-flag here /obj/Create_House_Constraints/OUT_PRIMARY_RDB_SIM_CONSTRAINTS and /obj/Pre_Fracture_House/OUT_PRE-FRACTURED_BUILDING and obj/Create_House_Geometry/OUT. As a final note, there is a few wrangles that are controlling the stiffness of the constraints here /obj/Primary_RDB_Sim/dopnet1/UPDATING_CONSTRAINTS The file was created using houdini 17.5.173. Thanks for the read. Any suggestions or any thoughts is much appreciated. Soft_Constraint_Attributes_Issues.hipnc
  11. Hi wonderful people of OddForce. How would you go about constraining an agent to a rigid object (not an agent but regualr rbd/bullet object), in a crowd sim?
  12. Hi all! There's 1 week left to register for my Mastering Destruction 8-week class on CGMA! In supplemental videos and live sessions we'll be focusing on some of the awesome new features in Houdini 18, and exploring anything else you might be interested in, such as vehicle destruction. For those that haven't seen me post before, I'm an FX Lead at DNEG, and previously worked at ILM / Blue Sky / Tippett. Destruction is my specialty, with some highlights including Pacific Rim 2, Transformers, Jurassic World, and Marvel projects. I've also done presentations for SideFX at FMX/SIGGRAPH/etc, which are available on their Vimeo page. If you have any questions, feel free to ask or drop me a message! https://www.cgmasteracademy.com/courses/25-mastering-destruction-in-houdini https://vimeo.com/keithkamholz/cgma-destruction
  13. Hey guys! I'm struggling a bit with a setup that's probably quite simple but I couldn't get behind it for a couple of days now. My shot requires me to have pieces which a character consists of (Megascan-assets scattered on a character) follow the character's animation. This looks something like this: walkcycle_fox.mp4 Now what I've tried to far was to go about the following with some fancy orientation math in a SOP-Solver in the dopnet to get the euler-W-acceleration to target the goal-orientation, but somehow the pivot offsets made this way harder than expected. My next approach (which I should have rolled with from the beginning) are constraints. So I'll try to have a soft constraint for each piece to a world anchor and target the rotation. But just how exactly does rotation-constraining work with the RBD-tools? I've found very little information on this topic - only for things that are individual objects, but not 800 pieces... I'm happy for any hint towrads a solution. Cheers, Martin
  14. Hello, What I am looking to do, specifically, is set up a symmetry constraint using Houdini's finite element solver. Basically, I want the model to be free to deform along the X and Y axis, but to be fixed in the Z-Axis. I know this can be done using the RBD solver, and setting your anchor's constraint type to constrained to a plane, but I can't get this method working in finite element world. If anyone has any advice on how to set up this kind of constraint your help would be greatly appreciated!
  15. Deforming constraints problem?

    hello guys. ive been bashing my head against the wall and read through way too many forums now. but i couldnt find something similar to my problem. Im trying to create for now a simple setup is to just break my glue constraints. The ball and colliding objects both have animation ( deforming). Now i do realize that my constraints get reconstrainted because of Overwrite with SOP option set to 1. however if i were to set it to 0 to only bring in the constraints on the first frame for the constraints to stay broken, the constraints would not be able to follow according to the animation of the ball, because it is rotating and changing position, leaving it very innacurate. So could anyone help me troubleshoot this? i think i have to somehow update the position and rotation of the constraints but i dont know how. I would provide a scene but it my scene is for a job. ive already tried matching position but there is rotation as well on the sphere, the resulting collision looks inaccurate as if its offseted broken_setup.mov broken_setup_position.mov
  16. Hello fellow magicians, I was wondering if some one could check out my simple constraint setup and see why it is not working? I was adapting my setup based on a wire tutorial by Entagma, and I don't know why but I couldn't get my constraints working. Here is the .hip file. Cheers, Diogo wire_debug.hip
  17. Entagma's "Connect the Yarns" in Vellum

    Hey there! I was wondering if anyone here know if this wonderful tutorial from Entagma can be replicated in Vellum. Any help would be appreciated! Thanks in advance!
  18. Hi Everybody, I've got a few (hopefully) quick question about Vellum Constraint Attributes! So I'm basically using the vellum grain solver, with a custom constraint network made in SOPs. I've been able to get what I think is correct behaviour by adding my own attributes for "type", "restlength", "stiffness", "compressstiffness" e.t.c However I noticed that there are some attributes that the Vellum Solver seems to add, such as "pts[]", "stress", "L" & "typehash". Not a problem so far, except when I add a SOP solver to my DOPs to dynamically add constraints these attributes are missing. I've been able to get my constraints to work by correctly setting the "pts[]" attribute, however do I also need to be working out the "stress" and "L" values? Are "stress" and "L" influencing the solver, or are they more like data out attributes? Finally, do I need to worry about the "typehash" attribute? I can't easily upload a scene while I'm at work but if you guys think it will help explain my situation better I can do it when I get home! Thanks in advance! M
  19. Vellum Hair Stiffness Falloff

    Hi, I'm working on some hair simulation for a groom setup using the grooming tools. I've been trying to get a stiffness falloff working so that the hairs are very stiff at the root, but become less so at the tip of the hairs, but haven't been able to get anything that works yet. Ideally I'd like to be able to put a ramp gradient along the guide curves that can then be multiplied against the bend and stretch stiffness values. Is this an approach that could work? Or should I be trying to adjust the constraints instead? I've attached a sample scene using a sphere with a gradient multiplier along the curves that I'm trying to get to work. any insights would be very appreciated! furStiffness.hip
  20. Hi, I'm currently working through Steven Knippings Applied Houdini Rigids 3 series and just got a bit stuck at the section where he converts hard constraints into glue constraints using a Prim wrangle inside a SOP solver. I've looked into the geo spreadsheet and it seems to do the conversion but the problem is when this happens the strength should be set to -1 and never break apart but instead all the pieces break apart and go flying. Tried messing around with different strength values and methods but can't seem to figure it out. Any help would be appreciated. I've included the project folder with some flipbooks and screenshots of what I'm talking about. Thanks Heli.zip HardConstraintTest(ODForce).avi
  21. vellum dynamic constraints

    I have basic tentacle-type setup, that's what I'm going for anyway... I'm creating dynamic constraints from a cluster of vellum points that are pinned to some SOP animation, and attaching to some vellum softbodies with no pinned animation. Done using the 'attach to geo' option on the vellum constraint DOP. The constraint creation is working, but I want the soft bodies to get pulled into the points that are creating the dynamic constraints (like tentacles pulling something in). I've tried by manipulating the rest length, but that doesn't seem to have any effect. Anyone know how to get this to work? Thanks! vellum01.hip
  22. Wire Solver Constraints Shifting

    Hi, Playing around wire solver and using the attach wire to surface constraint from the shelf tool. However I ran into issues where the constraint points would shift and not stick to their assigned points. On the help docs, it says to select points on the goal object, or just select the goal object and the tool will constrain to the closest of all the goal object’s points. I've created group of the points on SOP level and assigned them via the sbd constraint created in DOP but the points still shifts. Any ideas on what's causing this or is my setup approach wrong? Goal is to constraint the wire points to the GEO easily with groups so I can deform the geo anyhow I want and attach the wires. Thanks WireConstraint.rar eIcfCqUVie.mp4
  23. Chimney Destruction - Constraints Problem

    Hi guys, I have a problem, with constraints. I create a simple scene and get a desirable effect. It is a simple setup with a combination of strong glue constraint and soft constraint, which is fine. But this setup doesn't work as I want in chimney setup, so I have to change the setup to two glue constraints, stronger and weaker. I tried to convert weaker glue to soft when chimney falls down, and get effect like in simple scene example. This conversion I tried to accomplish in SOP solver in the constraint network. if(@Frame>115 && s@constraint_name=="Glue2"){ s@constraint_name="Soft"; if (f@distance > 1 ){ i@group_broken=1; } } This complete mess my constraints both strong and week. So any advice to accomplish this? I am sure that there is a more intelligent way to do this but I am new in Houdini and any help is more than welcome. Aleksandar chimney.mov Test.mov
  24. Dynamic Constraint Help

    Hi All, Wondering if someone could take a quick look. I'm having a hard time trying to get these dynamically created constraints to stick to this animated passive object. is my approach wrong ? What I'm trying to do is Have the sphere hit the wall, then pull away some pieces like its stuck to it. I've seen several approaches to this, but have not seen it done on a passive deforming mesh. Which is what the sphere is setup to be. Rich Lord has a some great examples of sticking constraints on fully dynamic meshes. any direction would be appreciated ! dynamic_constraints_deformingmesh_17.hip
  25. Hey all, I've tried searching the forum and the internet at large, but couldn't find an answer to this. Apologies if it has been asked before. I'm trying to create a constant stream of constrained vellum grains. Continuous emission with Vellum constraints (each frame/step) just explodes, and adding the constraints through a SOP solver made Houdini unstable.. Does anyone have any idea how to go about doing this? I'd appreciate any tips you could share. Please see a simple scene with the issue. Thanks! vellumConStream.hipnc