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Found 97 results

1. ## Why RBD solver simulates all of my packed geometries as a single object?

Hi; In my very simple "RBD" simulation, the RBD solver simulates all of my packed geometries as a single object. How can I fix it? Thanks. RBDPacked.hip
2. ## solver Seeking Solver Writing Advice

Hello there I am just getting into solver writing. I am self taught and as such I have a fair few holes in my knowledge I aim to build a material point method solver for use in a mud flow effect such as this: https://www.youtube.com/watch?time_continue=42&v=jjeCDYvGJS8 To get to grips with a basic solvers I have built a mass, spring cloth solver: https://vimeo.com/343112353. However there are a few things I've come across that I can't find solutions to. Every timestep I am accumulating a force vector on each point and then I find the acceleration using a=f/m. I find the velocity v=v0+a*@TimeInc. And I find the displacement using r=r0+v*@TimeInc. This works quite nicely however I can't shake the feeling that the equations are completely wrong. Everywhere I look they mention using integration in order to find the displacement but it seems like a linear equation to me. Is this wrong and if so what should I be doing? I would also like to know what the gas integrator node does internally as I find it a bit of a black box. Many thanks George Coleclough
3. ## Solver either not solving or stuck on frame 0

Hey everyone, just starting out with Houdini and trying to wrap my head around some effects I can produce, but I've hit a big of a snag when it comes to using a solver SOP on my animated model. The idea is that the model will be falling through the sky, and whenever a part of his body passes through some cloud, that part of the body will dissolve into cloud as well. So the the cloud points will trigger the body points whenever they get close enough. I'm using a solver SOP, having the points in the clouds use a PCFind node to trigger an attribute change in the points in the model. However, I have an issue when choosing the Import style for the solver's Prev_Frame. If I use Fetch Geometry from DOP Network, the model's animation freezes (in and outside of the solver) and nothing can proceed. If I use Transform Input Geometry, the animation resumes, but nothing seems to solve from the previous frame. I've attached a version of the file that has the some limited success in making the body dissolve, but the points snap back to the falling body as soon as they exit the cloud, and I have no idea how to proceed. Any clues on how to approach this problem would be greatly appreciated! CloudDive.zip
4. ## Wire solver from moving lines

Hi, I'm trying to figure out a saliva effect and am currently looking at the strands of saliva connecting the top and bottom of the gums and mouth of the creature tgats been animated and brough originally as an alembic (now cached to houdini geo) I've got points scattered correctly on deforming geomettry, then used point deform and add to connect the points, and have been following the entagma connect the yarns tutorial to resample the lines and set the mass for the connecting points to 0. However when I try to go to the next step using a POP network I can't figure out how to have the POP source update the lines and am only able to simulate movement if I create them on the first frame. Is there a mrelatively simple way I can get these lines and their anchor points into a DOP or POP network so I can simulate them to add some movement? I'm looking to mesh them and add then to some drool that im trying to put together using the condensation shelf tool. Any help is greatly appreciated EDIT: figured out the simulation using vellum thanks to Rohan Dalvi, although if anyone could give advice on how to mesh these look close to the strands in this video that would be amazing:
5. ## Curved Solver paths - Entagma intersecting lines

Hi guys, wonder if anyone could help me. A bit new to Houdini and learning a bit of vex and the solver sop. I followed along with an Entagma tutorial on intersecting lines that build up interesting grid like shapes. Was looking at trying to get all the point movements to move non-linearly instead of in straight lines. I figured instead of of just giving the points a random initial direction vector, could use sin/cos(time) as the directions within the solver, add a point and a poly line on each frame to get the curved lines, but can't seem to get it working at all. Any help would be much appreciated! attached my hip file from the tutorial straight line setup here. thanks Intersecting_Lines.hiplc
6. ## cops Solver in Cops

Hi there, I am building an infection solver in uv space using a vop generator network. I now need a way to run operations successively like in a solver sop and I am unsure how to go about this. I could take my data into dops and then back out again but I don't know how I would go about this as the dops data flow still has me a bit boggled. This video seems to do it. Does anyone have a solution to this? Thanks

8. ## GRAIN STICK ERROR

Hello Dear Houdini Community, I have been trying for hours to solve this problem. I have a simple simulation with grains, the basic idea is when the particles touch the surface more often they stick to it. they do not do that, they all disappear to one point in the scene, actually always 0, Y value, 0. Can someone look at it? Sincerely, Tim grain_test_collision_stuck.hip
9. ## SOP Solver and DOP import help

Hello all! I have a question concerning SOP Solvers in an Auto DOP Network. Im using SOP Solvers and switches to activate fracture geometry at certain times. I am trying to activate a second RBD object in the scene. Inside my SOP solver how do I specify which object the DOP import node fetches from the network? My_Scene.hipnc
10. ## flip/sph question - difference between solvers

Hi there, I got a curious question that I was hoping someone might shed some more light on if possible. What's the difference between the old sph solver, the particle fluid solver, and the new pop fluid solver? Is it all the same thing but wrapped in a new package, or do they have different utilities? Thanks, Felix
11. ## Running solver on multiple objects

Hello, I want to create a fire from multiple moving objects. I tried to merge them and create a Pryo source then plug this into Pryo Solver but this was a bad solution as the bounding box is getting very large. I tried to run foreach loop on each moving object and then create a pyro source and then plug the result into Pyro Solver but the Bounding box is now tracking the first object but not all the other. If anyone have good solution for this problem please share it with me, also .hip files are very welcome if you don't need to write a long solution i can just dig inside Thanks.
12. ## Wire attached geo collision

Hi, I like to do this... Create wires (kind of stems) attach the geo to the last point of curves (bloom) and during wire DOP collide the curves (wires) also with the blooms... How to do this? Sees to me like kind of cycles for counting this..? What should be the data flow? Thanks. B.
13. ## physarum polycephalum / slime mold PROBLEM(s)

Hello houdini guys, Im trying to simulate physarum polycephalum growth, but unfortunately it has some small issues. I would like to ask U on 3 main questions, if u will able to help me with any of them, it will be very helpful for me! 1. I have problem with VDB convertion as U can see on the picture, the distributed mesh (from wire extrude) is broken and VDB looks like particles. I dont know how to fix that. 2. In my file (I marked it with red network box) the small vein system of my slime mold, and I would like to connect it to the growing solver, but I dont know how. Basically I need this small veins with same growing properties like the big one have. 3. And last one is is possible to make the slime mold more "fat" on the edge? I dot hnow how to select this part of mesh? :/ ( like onreference picture) Thank U guys for any advices! Im looking forward! Bye! Physarum.hip
14. ## Understanding Solver SOP

Hi ! I'm pretty newb in Houdini and after a few months of training myself I'm trying now to create my own setup. Here I want to move points from a grid randomly to x or y position. A random value is generated every seconds to change the direction and the axis of the next move of each point. I already understand it must be completed with a solver sop, but I can't understand why amplitude is multiplied when I move points into the solver. I need to scale down a lot the movement. Anyone can tell me why ? Or just take a look to my project file here. Could be nice to have a little help to understand this issue. Thanks Dot_Grid.hiplc
15. ## How to merge multiple Flame ?

Hi every one (sorry for my english) I have a little probleme with houdini, I have to simulate 59 candle. I did just one simulation with a pyro solver, and after i did a copy node. So now I have 59 grid with 59 density, 59 temperature etc etc. But the renderer need only one Grid. So my question : How to combine all grid in one ? and keeping the temperature, density, vel etc etc Thanks
16. ## SOP Solver with changing numpt

Hey guys ! I'm currently working on a setup where I have to transfer Cd in a SOP Solver to "Curves" generated by Findshortestpath (in order to generate an attribute from this color). These curves are evolving through time, find more points to connect to, so the count of total numbers are going up. However, in the SOP Solver, it keeps the numpt of the first frame. So when I try to transfer P from the 1st Input, it does have the animation, but since it's keeping the numpt of the original frame, it tries to connect points and does not do what I want. Is there a way to tell him to actualize the number of points it's using ? Thanks a lot for taking time to read/answer me
17. ## cloud with interaction

hey! I'm doing some clouds (static) and I need to make one of them "dynamic" as a character jump out of it. since I created them with some geos, then convertem into volumes and applied some noise, so no solver obviously, I'm looking into some tips to convert it into a source for a dynamic cloud cheers
18. ## Wire Solver for ropes

Hello everyone. I was going to try Wire Solver for some tests similar to the ones that Ben Watts recently posted: https://www.instagram.com/p/Br1uOBqH8wm/ He said that he used Wire Solver for this and the result is amazing. So I started with a simple test: just a line with around 100 subdivisions which should fall to the floor. I used Wire Solver for that but can't get any remotely good results. The rope is self-intersecting and behaving strange. I used the shelf tool to create the setup and changed only the Elasticity parameters in the Material settings for the Wire Object. Set the Angular Spring Constraint to 0 and Damping to 0.001 and ticked on the Self Collide setting as they recommend in the Houdini help for wires or rope. I tried increasing the Substeps in the Wire Solver and in the DOP Network itself without any luck. The rope is still self intersecting. I also watched the M04 | Next Steps | Procedural Animation | Wire Solvers masterclass. But found nothing new ther. And of course I read help of the Houdini where they suggest increasing Substeps to get better results if there are self-intersections. Any help is greatly appreciated. Are there any resources to lean how to achieve the results similar to what Ben has in his test? Or any good tutorials on using Wire Solver for simulating ropes. I can't seem to find anything in Google.
19. ## Sop solver in For each loop

Hi everyone, I'm trying to make each connected points(@class) being deleted overtime when they above XZ plan. I made a bounding sphere for each @class and copy to itself with decreasing @pscale when it's above the plan. And delete the points outside the sphere. It works well when I set it to "single pass" but it works totally wrong when merges all iterations together... I have attached an example file below, it'll be fantastic if someone can help me out with this. sopsolver_in_loop.hip
20. ## wire solver

Hello, I have an issue with the wire solve, I have a point that is moving so I group that point, then I applied pin to wire pin to constraint, and or pinto animation, after that the first point goes directly to the center of my scene, does anybody know how Can I solve that ?
21. ## vellum Vellum Cloth and String weld

Hi guys, I'm playing around with vellum but something is bothering me: I want to attach a string to a cloth but I cannot do it if they are 2 different vellum objects in DOPs The example file will be much clearer than what I write but the question is: Does all the vellum objects need to be merged to build a constraint network, am I using the wrong method meaning I should create the constraints in another way ? Thanks for you help ! cloth_and_string_01.hipnc
22. ## Cutting geometry driven by wire solver using another object?

Hi there, I am currently doing RnD on an effect that I am trying to achieve that involves cutting a long strip of geo (think of it as a strip of plastic) using another object (blade) I have approached this head-on while learning Houdini and I have learned tremendously just by making mistakes and troubleshooting on the go - I have learned so much and this is the best part of learning Houdini in my opinion. At the moment I have tweaked a basic Houdini wire solver and used a Wire Capture to drive geo using that wire deformation. My question : I would like to know how I can go about cutting this Geo driven by the Wire using another object? The hip file with my tests is attached. Some tips I have found so far is that 1) You cannot fracture a wire instead, use a ConvertLine node (This warps my geo) I would greatly appreciate any help and pointers! Thanks wire_constraint_example_v02.hipnc
23. ## Distance between static object and fluid object simulation

Hello, I have a simple simulation task, where a static object and fluid object simulate. Emit Particle Fluid from a box to the sphere, I wanted to have a thin line of liquid so I made a static object bigger and box smaller, this way it goes as a narrow water tube, but the particles go too far from the static object, how to fix it? Where to look?
24. ## Exclude identical points from different arrays

I'm making an effect very much like this one from Entagma: https://vimeo.com/194277211 I've adjusted it a little and I noticed that some of the curves that get created collapse onto each other. I think it even happens at the very first frame. You can see that by the white parts of the lines. Those are the last created points. When two white parts meet, it means the curves collapsed and continues as 1 curve. What the setup does is it has a bunch of points as the active searching points. Each of these find target points in front of them and saves those in an array. Then a random point from within the array gets chosen and used to make the polywire. Sometimes, mainly at the very beginning, the searching points are close enough together so that they might find the same target points. This is where I believe the issue lies. What I would like to achieve is that I can check between the arrays on each of the points to see if they have similar target points and if so, remove those from one of the arrays. Or that when points get targeted by one searching point, they instantly get marked so that they can't be found again before the end of the timestep/solve. At this moment, I'm still trying to figure that one out. Any tips for this are much appreciated. Eckhart ObjectMaterialize.v005_00.hip

Hello everybody! I would like to simulate particles on top of pre-animated / pre-simulated (cached) points. So far I only managed to do the "transfer v attribute inside a sop solver" trick. Unfortunately it does not give me the result I imagine. Instead of inheriting only the velocity I would rather like the points to be attracted by the pre-animated points so they tumble around and follow them the animated ones. Basically I am trying to animate some points and then do a simulation on top of it to give it a more natural feel and to be able to art direct the simulation better. I would greatly appreciate if somebody could give me a hint or a solution on how to do that? Thank you! Here is my current progress (particles inherit v): pop_transfer_vel.hiplc
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