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Found 102 results

  1. Hello, I have a scene where I am emitting circles, where a POP wind is creating the noise, but I want to be able to limit it only on the Z and X axis. How would I be able to achieve this?
  2. Hi! Im trying to update the stiffnes of my pin to target constraint inside of a vellum contraint property , but when it updates it doesnt updates with the paint attibute im using to scale by the stiffness. Is there a way to do this inside the vex option on the vellum constraint property?
  3. Hello everyone ! In order to model a ceiling mobile (such as the ones in a baby's bedroom), I dived in the depth of wire objects, and I feel like it is much less intuitive than the usual DOP workflow. What I want to do is to tie certain objects (in my case, that would be origami birds modelled with the help of the amazing entagma tutorial from last week) to wires, which are tied to a static wooden part. The part where I'm having issues is when it comes to tying together the solid objects (which come as a RBD packed object) to the wires. I've tried several methods, all of which have failed me for now. 1. I tried using the SBD pin constraint from the Wire shelf. It kind of works, but I still find it very hard to control, and it is impossible to simulate the physical behaviour of the whole system (I have to simulate the RBD packed objects separately, and tie the wires afterwards). 2. I tried the more classical RBD approach, using constraint networks. This is the approach I would prefer, since it allows me to simulate the full system. I have set up the constraints using a Connect Adjacent Pieces SOP, which I modified a bit to add the anchor_id attribute on the constraint points. All of my pieces, whether it be the RBD packed object or the wires, come as separate objects with their own unique names matching the name specified in the constraint points. However, when I play the simulation, the constraints do not tie the objects to the wires, and the wires go wild while the RBD packed objects fall due to gravity. 3. I've started looking at Vellum and other cloth simulations, but I'm very new to it and it doesn't seem to integrate very well to RBD workflow which I'm used to. I've attached a hda with my project file, where I've replaced the bird objects with polygon spheres for simplicity. (It still doesn't work when I play it on my computer) If anyone has the time to take a look at it and tell me what I'm doing wrong or put me on another track, I'd be super grateful ! All the best, Nolan Constraint_Wires.hdanc
  4. Hello, the problem is, in the example file named "GravitySlideExample", this box only rotates along the x axis (red) given angle. BUT, I want it to rotate along y axis (green) without changing slider way. This is so important for making really easy and stable car dynamic rig. Is it impossible? https://www.sidefx.com/docs/houdini16.5/examples/nodes/dop/rbdsliderconstraint/GravitySlideExample.html
  5. Hey I'm stuck with something minor. I tried to create a simple popping balloon in vellum. If I use the edgefracture with a fracture curve (1 piece) it works just fine. If i try to use the "Initial Pieces" in the edgefracture sop it seems the whole thing breaks. Any idea what I could do to fix this? balloon_01.hipnc
  6. Hello all! I have been trying to figure out how to dynamically update the constraints in a vellum constraints property node based off of the distance of the vellum object from a given point in space, but I cant figure out how to make this calculation dynamically in this context. I can measure the distance before and after the vellum solver with a distance node but they only give me static values in the solver context so I dont know how far things are once theyve moved. Havent been able to get xyzdist to work either. Any help would be greatly appreciated as this project is very important to me!!
  7. Hello, question is simple but I couldnt figure out how to solve this. I am trying to make car suspansion mesh. The meshes that are bottom are connected to the wheel. Above meshes are gonna be suspension mesh. I connected them with "connect adjacent pieces" In my dopnet, I have "constraint network" with "slider constraint relationship" But unfortunately, slide axis is depend on world axis, not constraint axis. It makes me sad HOW HOUDINI does not have option that I can use constraint axis... Because of that, when I rotate car, that 4 constraints move too, but in Dop net, slide way isnt change. See the image bellow: SO, this issue is not just for slide constraint, same with cone twist axis too. There are two way to fix this; 1. option is, I am not gonna change position&rotation of my object in sub network (which is car). BUT How can I change it in DOP network? There is no "translate node" in Dop. (There is "position" node but it doesnt work like "translate" node) 2. Option is, "slider constrait relationship" node must have my constraint axis data. How can I do that? I have thousands of problems, this is just one of them.. THANKS !!
  8. Hello, I would like my drapped cloth to be a bit more pulled towards the bottom when I am simulating and not have it fly upwards too much. see screenshot. I just want the shape to stay a bit more consistent. I know that the arms are pulling the cloth up at some point, but I am sure I can cheat my way out of this!!! I created a @massgradient with a wrangle using the bounding box of my cloth. This feed into my vellumcloth>vellumDrape>DOPnet. So this attribute should be 1 at the bottom and near 0 at the top. How can I multiply mass by this attribute in the DOP? Is this even how I should do this? I tried using a Pop Property inside DOP, setting mass to 10, and in the VEXpression, typing @mass*=@massgradient; But this doesn't seem to do anything, and when I bump the mass to 100, it gets really weird and doesn't do what I would imagine. Any Ideas? If the cloth had a lower resolution, I wouldn't have this problem, but I want to keep this wrinkled look. Thank you very much
  9. Wire constraint network Question

    Hi all- Building a procedural constraint network for wires by connecting the interior points in a grid. It works fine for some grid dimensions, but not others, where the sim blows up. shown below a 5x5 and a 6x6 grid. A 15x15 grid will work fine, but a 6x6 one won't. Curious! I'm building zero-length constraints from the interior points and setting the anchor points as follows: int wirepts[] = nearpoints(1,@P,.0001); foreach (int wpt; wirepts) { if(wpt != wirepts[0]) { int pt1 = addpoint(0,v@P); int pt2 = addpoint(0,v@P); setpointattrib(0,"anchor_id",pt1,wirepts[0]); setpointattrib(0,"anchor_id",pt2,wpt); int newprim = addprim(0,"polyline",pt1,pt2); setprimattrib(0,"constraint_name",newprim, "WireGlue"); setprimattrib(0,"constraint_type",newprim, "position"); } } setpointgroup(0,"delete",@ptnum,1,"set"); I delete the original points later - I'm not using the first of the nearpoints to avoid a prim with the same anchor points, I thought that might be the problem, but it didn't seem to matter. Does anybody know the reason why this happens? Am I missing something? Thanks - I'm including a sample file. wireGridConstraints.hiplc
  10. If you look at the attached ColIgnoreA.mp4, you can see the "red" and "green" collisiongroup attributes ignoring one another. Results are as expected. In ColIgnoreB.mp4, with those same collision ignore groups, I glue one red and one green sphere together. The free red sphere now collides with the green sphere, which is not as expected. The best I can tell is that when these pieces are glued together, they somehow combine their collision groups. When I set collisionignore as "red green" it ignores them both. However I still want red to collide with red, so it does not work for me. What's more is that Soft and Hard constraints work as expected, ignoring green sphere collision. Only Glue is strange like this. Is there a way around this? ColIgnoreA.mp4 ColIgnoreB.mp4
  11. trying to hang a body on a rope

    Hi, I'm trying to hang a body on a rope. For now, I'm doing it using hard constraints. The main shape is fractured by Voronoi fracture and all the pieces are connected with hard constraints. The rope attached to it is just a set of spheres connected with hard constraints. So far, I don't like the results. The rope looks unnatural, way too springy and I don't know how to fix it. My questions are: 1. Can I somehow influence the behavior of hard constraints to eliminate springiness? 2. Maybe I should use a different pipeline altogether?
  12. Hi here so my subject is : Inflate and Pop a geometry ( Like the pig head) I'm feeding a remeshed pieg head with Pieces generated with a edge fracture into a Vellum cloth. Then i add a Vellum Weld and a Vellum pressure to sew the pieces and inflate the Pighead. Inside the Vellum solver i animate the Rest Lenght Scale to inflate the balloon. Now i'm trying to break it : I start playing with the Breaking Thresholod in the VellumWeld : i try different values but i'm not achieving what i want. So i create a vellumconstraintproperty in Vellum Solver and animate with Breaking Thresholod value. it's stay at -1. so it's not working at all. I told myself, i could animate a map or a group ( Like with RBD) and destroy the constraint inside the vellum solver. that would give me a lot of control but that's not working either ( or i dont manage to build something ) And i a saw some Entagma's Video and this but i'm wondering if i could have more control on that Any idear ? Have Nice day all !
  13. Hi guys, had a quick question regarding FLIP + RBD + CONSTRAINTS. i am trying to build a beach scene using FLIP. what i ultimately want is to have a small fishing boat, tied to the beach by a rope. so the fishing boat itself is affected by the sea waves, but is "constraint" by the rope (so it does not just float away). so far, i manged to get WATER simulated by FLIP + fishing boat as RBD object (volume collision) which is affected by the waves. i am bit lost on the ROPE part. initially thought of setting it up using HARD CONSTRAINT, but so far, can only set that up using BULLET SOLVER with packed primitives. could [WIRE SOLVER] interact with FLIP + RBD and constrain the boat? any idea or suggestion is much appreciated.
  14. How to manually break constraint

    how should i break my glue constraint by velocity enegry_blast.hipnc
  15. Hi, I am looking for how to import simed constraint object from DOP to SOP, in order to use DOP data (distance, impact attributes, etc, per primitive). I am guessing we should be able to import constraint data by Dop Import node, but there are something mistakes. I found another way that he turns on a constraint network node > relationship > ON attach internal constraint object parm, but I want to keep turning off this parameter. Thanks
  16. Hi everyone, In the case of an RBD simulation with constraints, is it possible with a sop solver to copy or transfer the constraint attributes and broken group (which comes from the relationship_geometry Object Merge node) to the dop geometry? Basically I would like to use these attribs (angle, distance, torque, etc.) and broken group after the dop import, but I can't really get them. Do you have any idea?
  17. Hi! I'm trying to use the new Sliding constraint in vellum (houdini 18). I had good result when I tried to constrain my geometries to a collider geo. (Using the Attach the geometry or the Stich constraint node.) But when I'm trying to "Sliding constraint" together my geometries, I can't make it work. So basically, I want my active vellum objects "sliding constrain" together many shells of geometries. Any ideas? (Not too much info in the docs sadly. https://www.sidefx.com/docs/houdini/vellum/slidingconstraints.html)
  18. Hi, Does anybody know how to add an extra point group to a fem region constraint, or a different way to constrain points from one object to an animated object with different topology? Cheers!
  19. bullet metal bending by constraints

    hi, I have a question about bullet sim for metal bending. Goal is to able to bend many times by a certain condition. So far , I tried a couple of tests, but never work properly. Outline of my thought and trials are: - hit a box and metal is bent momentaily and stop motion and keep a shape completely . And repeat to hit a box and metal is bent over and over again.... - use Glue and Soft(or hard) constraints to switch each other in SOP-solver by conditions of primitive attributes: impact, force, torque, etc. - probably we should not 'next_constraint_name' attribute in order to repeat switching constraints. - When using impact attribute to trigger switch glue to Soft constraints, fraguments start jiggling. This is because I guess fragments geo struggle with mixed constraints. Some constraints are connected as glue, and others are as Soft. - probably when switching constraint type, I should switch a whole fragments, instead of just a hit collsied pieces, in order to avoid strange jiggle. - If I just need one time bending, it's easy. Just picking one frame to switch a whole constraints to Glue. - maybe example pic has too many colliding boxs. Colliding could be happening every 50frames.. Thus, if anyone gives me a very smart rig, it would be amazing, thanks!
  20. For some reason, I am having a difficult time constraining RBD objects to animated geo. I have done this in the past inside dops, but I am trying to do it in the new RBD workflow. I am fracturing a box and then successfully creating constraints to static ground geometry. I am then replacing the static ground geometry after creating the constraints with the animated one, and using the rbdconfigure to make the animated ground non-active, animated, and deforming while keeping the fractured box with the default settings. My animated ground is moving as expected in the sim, but it doesn't look like the constraints are moving the box with the ground's animation. Is there something I am missing? I have attached a simple scene explaining what I am referring to. Thanks in advance for the help. rbdHelp_v001.hiplcrbdHelp_v001.hiplc
  21. Hi, I am trying to get a tearing effect constrained to geometry. The effect I am after is a bone breaking and the flesh on top of the bone being teared apart. I nearly get the effect I want but I am struggling with the constrains. When the static object are being pulled apart (cubes on the image), the constrain is still active (see circled in red on the image) resulting in part of the fem mesh to jump side. I am looking for a way to deactivate the constrains when it is away from a set distance. I have attached my file. Any help would be greatly appreciated. Thanks. flesh_on_bone_RD_02.hip
  22. Constraint to animated geo

    Hi, I am following this tutorial (https://vimeo.com/305543446) , but I want to constraint end of the chain to my animated geometry. I tried couple of things but i can't work it out, anyone could help me? Thanks Mike chainTest_odforce.hip
  23. I tried to fix it by creating a constraint property but this collapses so easily. I kept looking for a way to neatly create constraint attributes and I thought it was the way to do this but I was very dissappointed because I couldn't do it... Please tell me why this simulation collapses even though I added it. I would be very happy if you let me know it. houdini_wood.hipnc
  24. I want know how to control the constraint primitive node. I want make the collapse the house but this house easily breaks like a cookie even though adjust the constraint primitive. I have been tried a lot before, but haven't found a way. I would be very happy if you helped me.... house.hipnc RuralStall.obj
  25. I have a number of wires in a wire solver that I want to connect end to end after simulating for a while (snap together essentially by keying group_broken on), but they are currently joining with a pinched angle, instead of straight on. 1) Does anyone know what determines the angle of the constraint? -With some experimentation, it seems it's not determined by the geometry immediately prior to binding, but rather the relative angles of the wires of the initial geometry. I don't want to align the input geometry, but rather change this constraint angle internally. Image 1 is immediately prior to binding, and image 2 is the bad angled join. If I manually change the input point positions so they're aligned (image 3), then they join straight (image 4). Any suggestions are appreciated! Bonus question: With the wire solver, the restlength of the constraint doesn't seem to be respected, it's always 0. Is this a limitation or am I doing something wrong?
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