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Found 112 results

  1. Hey guys! I'm trying to wrap my head around the solver sop. I have an alembic geometry that needs an attribute for the frame any point started changing position. What I tried was, inside a Solver SOP, appending a Point VOP where I subtract the rest position from the new one, compare the length of that delta and then write the frame on an attribute. The test and such works fine, but then my frame keeps changing, which I understand that it happens because I haven't figured a way to stop the value from changing. What I'm trying to achieve is to do a color ramp on the points by the attribute that tells which frame started moving. Any help will be very much appreciated! 20200316_CubeAnimation.rar
  2. Hello guys, Just a quick question. I'm studying new Sparse system for Pyro Solver in H18. First change I could see is that Pyro Solver sparse has 4 inputs rather than 5 and “Velocity Update” input is missing. Let's say I want to use a Gas Disturbance micro solver for sparse smoke. How I can connect it to the solver? “Shape” tab in the solver already has a Disturbance option. But, of course, the result is different if I use only the Micro Solver connected to the last input (Forces). So I guess, this approach is wrong. How I can achieve same result using only Micro Solvers? And, first of all.. Does new Sparse Solver allow to use micro solvers? Many thanks!
  3. Smooth Pyro Dissolve

    This is roughly what I'm trying to create, only with a smoother transition. In the example, the smoke is being generated by an animated gradient ramp, and the opacity of the text geometry is controlled with another ramp at render time. With Houdini, I want to utilize another workflow, I'm importing the whole text in my pyro sim as a fog vdb. But I don't want the whole text to be affected at once, I want to gradually dissolve the text from left to right, similar to the shown example. 1. (How) Can I drive the 'activeness' of the pyro solver with an attribute? 2. How can I make my density text vdb as opaque, as if it would be an sdf? Thank you in advance!
  4. Greetings, I have few microsolvers in my Flip Solver>Volume Velocity and I want to apply them to only 1 of my 2 emitters. Do I use a POP Wrangle after my MicroSolvers like (if viscosity > 500 then apply) or do i need to make some initial groups of my particles and apply the micro solvers to the favoured group ? To be more specific I use a GasMatchField and a GasStrainIntegrate with a GasStrainForce and I have 2 Volume Sources. If for example I go to my Popdrag in Groups I can see the option "stream_volumesource1" or "stream_volumesource2" but nothing like that in the microsolvers.
  5. pyro solver advect rbd piston

    hello. previously i saw a hip file in the forum about internal combustion of car engine pyro solver ignites and mooves the engine piston that in turn moves the gear of the car wheel. i searched for it but i cannot find it any help please thank you
  6. 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
  7. Object Propulsion

    I'm trying to recreate the effect of small pieces of dry ice propelling themselves across the surface of water. First step was to figure out the propulsion. Thought I'd post my solution in case anyone was interested. The basic approach is to take a number of points on the surface of an object and use their normals as propulsion vectors to move and rotate the object in a (somewhat) physically accurate way. The points and normals can vary over time to create more random behaviour. This can probably be incorporated into dops somehow but haven't looked at that yet. It is also entirely likely that this is trivial to do in some other way and I've wasted my time. If so, please let me know. mt__propulsion__1_0.hdalc
  8. Smoke from scratch, add force

    Hey dudes, I'm trying to build a simple smoke solver from scratch to understand more how they work. I created a simple setup with density, temperature and buoyancy. Now I want to add a second velocity volume as a force to my simulation. But when I add the force, the velocity is increasing massively in a few frames. I have to mix my force with the existing velocity but I don't understand how to do this my_solver.hiplc
  9. hey guys i have a rigged character from 3ds max and exported it into fbx format.. and imported it into Houdini.. but the main issue is this.. the solver node is not working on animated mesh...its only reading a single frame :-( any suggestion.. i have attached file Hand_FInger.hip
  10. FLIP VORTEX SIMULATION

    Hi, I'm doing a project for a short film; and I am trying to create a water vortex. I looked into a few resources creating custom vector sources etc but I realised that I am having trouble using my custom vector source to drive a (basic) FLIP simulation. Do you have any alternative ideas that I could explore? Cheers.
  11. Hi everyone, I'm working on a little project of mine and I'm using wire solver with SBD spring constraint. I have attribute set up on the points(before the sim), but when I try to feed the strength parameter the expression with that attribute, it acts as if the attribute was zero. The vexpression I use goes like: @theattributementioned * 1000 I've created basic example file of what i mean. The attr “mult” is what I want the strength to be ( for example “@mult * 1000”.) Any input on this would be great Thanks, Hubert wires.hiplc
  12. DOP not keeping the dent done in SopSolver

    Hello, Alberto here! I've been following many tutorials and checking many examples in Houdini Help but after some days I'm getting a bit lost with this. I'm trying to do modifications to points in a geometry using an extra solver, during a Dop RBD simulation. I've tried to reproduce other working examples that I've found over the web but when I do it by myself, is not working. I want the extra solver to keep the denting based on impacts during the simulation. I read and saw examples about "Unpack - Do The Operations - Reassemble" inside the extra SopSolver and that's what I've tried to do in the attached file. I get the dent only in the frame of impact, not keeping at all any of the deformations during the rest of the simulation. I'm not asking for "fixing the file", I'm more into understand what I'm doing wrong and why. Anyway, Fix the file will help Thanks everybody in advance! Metaballdent_extrasolver.hipnc
  13. Hey guys iv'e been struggling to understand about Jacobian matrix and eigenvector why they are used in smoke solver how can they effect the look of simulation? Any ideas? Thanks
  14. The correct way to handle collisions?

    Hi there. I am currently building a cloth solver and have just got onto external collision handling. For internal collision I am using the same pbd approach they show off in the grains masterclass. I thought I would go about external collisions a similar way, using a gas collision detect I get the incidence vector and reflect it. Then add the resulting reflected vector to the position. if (i@hitnum) { vector incidence= v@hitpos-v@P; float mag=length(incidence); vector reflection= reflect(normalize(incidence), normalize(v@hitnml)); v@P+=reflection*mag; } The cloth still blows up, even at a high substep Annoyingly a simple if (i@hitnum) v@P=v@hitpos; seems to work worlds better albeit the colliding points get stuck in place (which is something I aimed to fix by setting the new position to the reflected vector). The reason I'm not using the gas integrator to handle this for me is because I was looking to learn how this system is implemented. What is the correct way to go about this? As always any help is greatly appreciated Thanks
  15. Hi all! Just a general question here. Having a solver inside a for-loop, looping through objects. I realize I need to turn off caching, or else it doesn't read in every new piece correctly. This seems to be extremely slow though, so I'm just wondering if there's a way to optimize this? What I'm doing is having an RBD sim, and having the pieces erode away. So I cached the sim, eroding the fracture elements in a for-loop and transfer the new pieces back to the simulation points. I hope and think this is a decent way to do it, except it'd be nice if I could cache out and iterate on the solver loop faster. Having 150 pieces, it's cooked 35 frames in 25 minutes now, and that's with a low-res VDB conversion, and naturally getting slower for each frame.
  16. 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
  17. 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
  18. 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
  19. 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:
  20. 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
  21. 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
  22. Volumetric Temporal Deflicker 2.1

    Digital asset download at Orbolt! Enjoy https://www.orbolt.com/asset/RodTD::Rod_vdb_averaging
  23. 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
  24. 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
  25. 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
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