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Found 74 results

  2. 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
  3. 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!
  4. Deforming constraints problem?

  5. 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
  6. 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!
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. [SOLVED] In/Active Constraints

    I'm trying to shoot a cannonball through a small castle. The cannonball animates and blasts through the walls, but the constraints look like they're being ignored (or they aren't hooked up properly), so the entire structure collapses the moment the sim begins. The clusters are being ignored as well, but I can't figure out why. Many thanks for you even reading this. v17.5 rookDestruction_chazS.hipnc
  16. Hi everyone, Currently i'm running into an issue where my constraints aren't breaking. I spend a while on figuring out why it doesn't work and I still don't have a clue what i'm doing wrong. My setup at the moment is that I have one curve with 3 constraints 1 hard constraint to keep the wire in place. 1 spring constraint that is pulling the wire down (This is a placeholder for collisions later on. It's just there to apply a force for testing). 1 spring constraint without a strength to measure the angle between the tip and a point somewhere on the curve The thing is, when i put them all in one constraint network and break them based on the angle, nothing happens and i couldn't figure out why. But when i put the spring constraint that is pulling the curve, into another network the breaking works! Is there anybody who can explain why this is happening? Why wouldn't it break with all the constraints in 1 network? Is it because i pinned one of the points of that constraint to a wold position instead of a point on the simulation geometry? That's the only thing i can think if that is different than the other constraints. Thanks! break_constraint.hipnc
  17. Wiggling Fur

    Hi all, I created a vellum fur simulation for my chimpanzee that simulates the guides perfectly. But when I render, the actual fur, especially the longer hairs, are wiggling like crazy. It is especially noticeable thanks to the white hairs I have. As far as I know, I have no wind forces activated. I've looked around and tried many different renders with different sim parameters but the same always happens. If anyone could take a look I'd be grateful. I'm attaching the project with some renders so you can see the problem. I deleted things like textures and sim cache to keep the file size smaller, creating the cache is quite quick anyway. If anyone has any questions about the setup just let me know. Thanks in advance ~Tomas
  19. Animated colliding objects

    I have a project coming up that will require me to hand animate objects but get them to collide with one another. I'm an experienced Houdini user but setting up DOP simulations has never been my strength. I've attached a hip file with the basic situation here: moving_furniture.hip Furniture will be sliding around, probably animated by hand. The objects need to bump into one another and react naturally while doing their best to follow the target animation. I had assumed that this would be some sort of combination of RBD objects, proxy Geo & pin constraints, but I've been unable to understand how to wire it up. There are so many great examples using this sort of thing but nothing that really explains how to combine following constraints that are animated in world space. Thanks so much
  20. Hi everyone, my name is Tomás and I'm new to the forum. I'm creating a fur sim for a chimpanzee using the Guide Simulate node with the Vellum solver. The chimpanzee will later be animated. The sim works fine but I can't find a way to make it keep its wild messy look. The guides do keep their shape (bend, guideinit, etc) because I increased the constraint iterations and the bend stiffness. But I can't find a way to make the hairs keep their direction. In other words, once the gravity affects the guides they all go too down. So I want a way to keep the original shape of the hair a bit more. I could tone down gravity or the mass of the guides but that would make it look as if it's underwater or something once I animate the chimpanzee. Increasing the constraint iterations to a ridiculous value would maybe fix this but at a high cost to sim time, same for stubsteps. Increasing Bend Stiffness to billions and billions doesn't seem to help either. Obviously, I don't want the hair to be hard as rock. I want it to behave this way because it's light, strong and covered in dust and sweat, if that makes sense. It's also important to note I committed the noobie mistake of not resizing my mesh after exporting from Maya which works with different centimeters instead of meters. Meaning my monkey was more than 100 meters tall. I believe I already fixed this by going to preferences>Hip file options but I did this after creating the simulation so I'm not entirely sure if everything was resized correctly. Attached are 5 images: the guides at frame 1, the guides at frame 73 (3 seconds into the sim), a render of the fur at frame 1 (the way I like it), a render of the fur at frame 73 (the way I dislike it) and a reference image for the sort of hair I'm aiming for. I also added the project folder. ApeODForce.zip Thanks in advance!
  21. I know their are already a lot of threads on this topic but I can't seem to find one that matches my situation. Maybe i'm approaching this all wrong by using pin to target to begin with. I would like to create a raffle machine type effect where a very long stream of tickets come out of a slot into a box. Right now I am using pin to target with a geowrangle inside the vellum solver to change the stiffness value to a low number as the tickets enter the box. if i make the stiffness value a really tiny value this will work and prevent the tickets from getting pulled into the side of the box but it seems like i could take a better approach. any ideas? thanks in advance! lottery2.hip
  22. Multiple Constraints on One Object

    I was wondering if anyone has had experience having multiple constraints on the same object and breaking them apart separately. the effect I'm aiming for is to have a some large rocks be ripped of a section of rubble and while in the air start to break apart into smaller pieces. I've tried setting up my constraints based on the groups created from the Voronoi fracture and sub fracture nodes, however this causes problem when trying to disable the constraints in different areas. Any ideas? ConstraintsHelp.hipnc NewRubble.abc
  23. Hello houdini wizards! I am playing with Vellum and trying to get the dynamic glue constraints to work. The documentation is about 1 very small section and I did what it said to (like creating the glue inside the solver and setting the Create Constraints drop down to Each Frame) but it does not grab the cloth. I played with distances and groups but no luck. I don't have a specific scenario at the moment so no scene file really that cant be set up in 2 minutes, just a grid as the cloth object, a sphere (fed into the collision input at the sop level) that dips down close the grid and then moves back up. The intention is to have constraints be created to grab the cloth within the set distance, pick it up, pull it, and then release/break the constraints when I want/need to. The breaking I can assume is pretty simple using the broken attribute in the Constraint Properties but I cannot seem to dynamically create constraints to grab the cloth/grid. Any help or knowledge you can give is much appreciated! I was unable to find any example files on the subject either but I did see the demo of it being done (https://vimeo.com/313872854) around 24:50. And again, thanks in advance for any advice you can give!
  24. Breaking constraints

    Hello guys I'm doing some testing on breaking constraints, for now, I was only breaking constraints based on angle, force, torque and using a slider for adjusting values. Do you guys have any techniques to share for breaking constraints, what kind of rules can be used?
  25. Hi, I'm trying to wrap my head around why this simple set up isn't working as desired. Inside of an SOP solver, I look for the first and last points on a curve and assign them to groups. I then try and assign these groups in the Stitch constraints on a multi-solver but they aren't taking effect. Can someone point me in the right direction? I know this is simple in SOPS level but I'd like to expand upon this in DOPs and make the Stitch points animate-able. Thank you constraint_simple_01.hiplc