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Found 116 results

  1. gas fluid resize artifacts

    Has anyone else encountered artifacts with the Gas Resize Fluid Dynamic node? I've attached a simple file that shows what I'm talking about. If you dive into the dopnet, view it from the top orthographic view, and play the first 20 frames or so, it's clear that the fluid is developing grid-shaped artifacts that are *larger* than the resolution of the fluid itself. If you enable the timewarp node inside sphere_object1, you'll see that the artifacts still develop, but much more slowly. So it seems to be related to the rate of change of the size of the fluid. artifact.hip
  2. Hi everyone, I am trying to simulate a bacterial growth scene by using wire objects. In story short i am splitting a wire object every 15 or so frames and getting an exponential growth. But my problem is that, i want the new split wires to try to come to constant length (like a pressed spring). and i want them to push each other away. Please take a look at my file. Am i even in the right direction?. how can i make the lines grow back to a size? by giving them a rest position every frame? thanks in advance. bacteria.hipnc
  3. Hi Guys, Missing some basics here.. I want to be able to Visualize force vector field from, lets say Gas Vorticle Forces (using vector field viz) and Modify ( gasfield vop/wrangle) it pre solving step. How do I go about doing it ? Thanks, -GM
  4. I have a RBD sim, with 1 packed object which contains 9 elements. I am trying to disable the gravity only on certain elements, within the packed object. In order to achieve this, I would like to control the gravity node with a dop group. I created a point attribute "falling" which I control in a sop solver, within the dop network. Then I created a DOP Group that creates a group based on the following expression: point($DOPNET+":"+$OBJID+"/Geometry",$OBJ,"falling",0) Now, this seems to work but ...not quite. I see elements that start fluctuating at a certain moment, but this moment doesn't match the moment when the "falling" attribute is triggered to 0. To start, I'd like to understand if I am using the above expression correctly. I am quite confused with the global variables $OBJID , $OBJ used with Packed Objects. Could anyone shed some light on this? I am on H13.0.547
  5. Wrecking Ball Constraint Question

    Hi! I've setup a simple scene with a wrecking ball with a chain hitting a brick wall. I've two constraints network a hard constraint that takes cares of most things and then a glue network that keeps the ball together (it's made up from two pieces). The brick just sits on each other and contains no constraints. Everything seems to work fine from the exception that the hard constraints starts to stretch (ie the chain starts to stretch) when the mass of the ball becomes too high. The only way I found to get around this is to increase the density of the chain to 10 times the ball. But it just doesn't look alright. Is there another constraint I should use instead of the hard constraint or is there a way I can increase the strength of the hard constraint without increasing the mass of the chain? Thanks! / John WreckingBall_Constraints_V01_01.hipnc
  6. Hello guys! I would like to ask you what do you think it would be the best approach to absorb a volume in a DOP simulation in Houdini. I thought of one but it might be wrong: Creating a spherical volume, then with Volume VOPS storing the gradient into an attribute and using it as a scaled force inside the DOP network. What do you think? Is there any other approach it comes to your mind? Thanks!
  7. Hi guys, Does anyone have a way of iterating through impact data inside a VOP Force DOP? I've created a bunch of points in SOPs that is pulled from an ImpactAnalysis node, and I need to access it from a VOP Force DOP. I've tried pulling the points into the VOP Force as a pointcloud, and I've tried using the GetAttribute node too, but they don't work with the "op:/obj/myimpactpoints" syntax. (Is it me or is that syntax pretty flaky? It's an endless source of frustration for me!) What I'm trying to do is use the impact data to generate some custom frictional ground forces for a wheel. I can calculate the forces easily enough and apply them in the VOP force, as long as I can get the impact data in, but I can't get it in there. Is it possible to apply forces and torques in a SOP Solver instead? Suggestions welcomed! Thanks, Andy
  8. Gas Sand Forces Microsolver

    Hey Guys, I've recently had to investigate simulating sand. I've manage to find a work around by combining a few different techniques which seem to work for the shot, however i came across the Gas Sand Forces Micro solver and would love to know how to implement it. I don't know if the micro solver will do what i want, I'm doubtful that it will. Either way i would love to know: A ) What it was designed/used for ? B ) How it can be implemented ? I'm hopeful that it plays well with the Flip Solver, although I have a feeling that its something left over from the old "sand" solver, that the the new Flip solver is based off and it being legacy... Any insight would be great! Cheers!
  9. Hi, I'm trying to set the activation of pieces in an RBD fractured sim by using an attribute created from the density of a volume in SOPS. But when I run the sim, pieces that aren't supposed to fall fall, and pieces that are supposed to don't. When I look at the initial attribute created through the volume, and the activation values in the DOP data, it appears to be correct, but it doesn't sim properly. I have no idea what to do to get this to work properly . I'd really appreciate any input anyone can give me to help fix this!
  10. Looking for floating object ideas

    Genius Houdini Community! I'm having a hard time wrapping my head around something so I thought it best to ask the experts out there. We're about to do a project where a rigid object ( like a box or a tea kettle ) is floating weightlessly in a room. It is being blown around by wind and bumping into objects as it goes. What we would like to do is loosely keyframe the object for basic choreography and timing but have the dynamic object "follow" it, like a target. This way you get the benefit of having keyframed motion influencing the dynamics. Would a sop solver be the right way to go here? Field force? It's been a while since I used dops so any advice or examples would be appreciated. I'm sure there's an elegant solution out there but I'm just not able to think of it. Thanks very much!
  11. reverse rigid dynamics effect

    Hi, I am currently struggling to create reverse rigid dynamic, something like this But instead of cubes, I have a voronoi fracture pieces. I found a way by using attractor but its not accurate and having some problems. Could anyone suggest a good idea to achieve this kind of effect.
  12. Hi -- I'm trying to figure out a way to get animated/deforming geometry working for packed primitives in dops. I really like working in VOPs and SOPs, so the packed primitive workflow is really appealing to me, but I can't seem to figure out how to get animated/deforming colliders. I have gotten my packed primitive to animate and match the animation in SOPs, and activate based on an attribute This is my best attempt so far. Inside the dop network, there is a red switch node. You can switch between the packed and unpacked primitives, for reference. The unpacked primitive never gets released to becoming dynamic, but maybe it's useful. Inside the green sop solver in the DOP network is another red switch node. The first input here works great after the packed primitive becomes dynamic, but doesn't collide properly/at all until then. The second input works while it's tied to the animation, but gets all squirrely and weird afterward. It's almost like the pivot point is totally off, or.. I don't know. More confusing than that is that the guide geometry is clearly not what the bullet solver is colliding with, since the guide geometry is in the right place. Could someone take a look and see if there's a better way to do this? All I want is for my packed primitive to be tied to some SOP animation for a while and then become active in the scene. Also, as an aside, do DOP groups work correctly and reliably in a multi-solver? I know it's a dumb question, but I have had a pretty hard time isolating which geometry my solvers are running on so far. Thank you so much to anyone who can help :-)
  13. Does anybody know if a DOP Network automatically generate sub-integer frames if you set sub steps higher than 1? For example, if I pass in some geometry from SOPs that's saved on disk in integer frames, does DOPs automatically interpolate subframes, of would I need to use a Timeblend to generate subframes.
  14. I wanted to create an effect where an attribute could be transferred and then spread throughout the object - I found the scene on this page which worked great: http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=28148&view=next&sid=1030caf41e7f90f948b8db61b7222608 However I need to do the same sort of thing inside DOPs - I want to have some highly viscous fluid and melt it with another object then have the heat (or lower viscosity) spread from the point of contact. I've tried using a solver sop inside of a sop solver (connected to the particle motion of the flip solver) however this doesn't seem to work as the solver is using the previous frame so the simulation can never progress (I think thats whats going on). So I basically need to transfer my custom attribute before the pre-flip-solve. Is there a way to do this? I've attached a scene file with my current progress Thanks, Mike wax_melting_v02.hip
  15. I'm trying to compile the Field3D plugin on windows in order to transfer smoke from Houdini to Fume. This is the command that I'm currently running from the field3d directory where f3dtools.C file is located: hcustom f3dtools.C -i c:/ie/ark/programs/houdini/houdini13.0/dso -L "C:/Program Files (x86)/Microsoft SDKs/Windows/v7.0A/Lib/x64/" -L "C:/Program Files (x86)/Microsoft SDKs/Windows/v7.0A/Lib/" When compiled with no change to the code, the compiler complains about error C2664: 'void GU_Detail::sortPrimitiveList(GU_AxisType)' : cannot convert parameter 1 from 'fpreal32 *' to 'GU_AxisType' If I comment out this line, then the compiler gives a classic fatal error LNK1120: 25 unresolved externals. It seems like almost all of these errors are LNK2019: unresolved external symbol in the f3dtools object file, followed by a string beginning with: "__declspec(dllimport) public: class std::basic_string . . . . . ." Is there a precompiled version of this plugin somewhere? I'm surprised it's not just included by default, without it there's no way to get smoke out of Houdini which is a big barrier to adoption. Thanks for any help you can provide!
  16. steering large billowy smoke

    Hey guys, I have a large billowing smoke sim a wall of smoke from different sources. I need to steer the volume, like have it turn at a certain point. What is the best approach to steering or having thick volumes follow a vector. Right now I've tried guiding the smoke using pumps by making some geo that acts as a wall with custom velocity vectors to push to smoke around. It sort of works but the smoke expands a bit too much and doesn't really seem like its being directed, also seems to lose it's volume. any tips would be appreciated
  17. Pillar shatter- RBD Packed sim

    hi all ! I am sparring my time in learning alot with Collisions and RBD sim, with the new h13. Now wat i am trying to achieve is , i have an animated character which eventually ramms into a pillar, and the pillar cracks , falls down, i have animated it, cached it, brought into Houdini as alembic file and ropd it again.. all good. but when i add that as an deforming rbd object and let it collide with the pillar i m loosing my brain there.. the problems are, its a fractured pillar and brought in as packed geo, if the gravity is on, the pillar just crumbles all the way down ... and another one is, its a huge character with lots of force in action. i cant get that as it hits, the pillar, i have attached a file and a screenshots of wat i am trying to say! take a look at it and shed some light on wat mistake i am committing in here the roped animation is also attached as a cheap way,i am just turning on gravity on a certain frame , where the character comes closer to the pillar, u can see that in the play blast.. i know i am wrong but i m still learning cheers test_1.hip untitled.mov cache_anim.zip
  18. Hi All Im quite new to Houdini and have a possibly basic problem to tackle! I've set up a fracture system for a barrel I want to simulate exploding. In order to fracture each wooden plank of the barrel separatley (and avoid the voronoi fracture smooshing all the geometry together) I've used an assemble sop to split them out into primitive groups and a foreach node to iterate through each piece with my voronoi fracture setup. This seems to work well and the foreach node spits out my barrel with 25 primitive groups, each one fractured the way I want however when I create an RBD setup the second assemble SOP that creates the packed primitives doesnt pack all the individual shattered pieces correctly (either grouping to few primitives or if i tick "create name attribute" separating out every single polygon). As I say im relatively new to the wonders of houdini and might be missing something glaringly obvious with the way im handling primitive grouping down the node structure but any fresh insight into how I can send my shards to DOPs correctly would me massively appreciated. Thanks in advance for any help! J. FractureSetupTEST.hip Models.rar
  19. So went to use pop replicate in dops. Looks like it does not apply its life expectancy/life variance to the new particle. It either inherits the life from the original particle, in which case your new particles lives only as long as your last ones, or if you explicitly tell it to not inherit life it defaults to 100. I went as far as to create a scene that is purely SESI's default fireworks setup, went in and set the life of initial particle to 1 no variance, life of replicated particle to 4, no variance, watched in details view as it played out. Life is either 1 or 100 depending on if I ^life on the attributes tab of the replicate node. I mentioned this to some of my colleagues and it seems that they had issues with it too, I've emailed sesi, but if anyone else has experienced this or knows of some magical checkbox that makes the node actually work, or if its a version thing then plz let me know. I know I can make it work manually using a pop vop or vex and just setting the attributes, just reporting the bug with the node to see if anyone else has had the issue. I attached the fireworks that shows what im talking about if anyone is interested or just wants to watch some freagin awesome fireworks particles >.< Im running 13.0.368 Starting to miss my sop based pops sesi_popReplicate.hip
  20. I use sop solver for deform my spheres in DOPS, but they don't interact together correctly. Help me please!!! spheres2.hip
  21. Hi everyone, I'm quite a beginner in Houdini, so maybe someone can help me with this issue. I'm trying to create an erupting volcano with Flip Fluids (the lava, not the smoke), so I modeled a geometry which I'm trying to use as a collision in the DOP network. Now, when I'm trying to use the fluidsource SOP I get some weird artifacts and can't really manage to get a decent collision SDF volume. One thing I've noticed is that the new VDB volume is really fast and gives me a very good result, but even after I've used vdbconvert to convert my VDB to a default houdini volume I couldn't use it as a collision in DOPs using the sourcevolume DOP. (Please check my attached pics.) Are there any tips on how should I handle this problem? Is there a way to make this VDB volume usable by DOPs or ar there some parameters I can tweak that make the fluidsource SOP output a good collision volume? Thank you.
  22. Hey All: This is a lay and perhaps naive approach I put together for getting rotations in H13. Attached is a file that has this approach. My physics no es bueno, so I'm wondering if anyone here can tell me if what I'm doing is kosher. It certainly seems to get me what I think I want. Here's an outline of how I went about it. I implore anyone here to tell me if there's a more correct or elegant solution. Randomize the mass of the particles. This affects their speed/acceleration based on the force applied. Calculate speed by getting the length of the velocity. Create a rotation axis based on velocity. I did this by getting the cross product of the normalized velocity and an up vector (0, 1, 0). Set torque.x, torque.y, and torque.z to my rotaxis components. Use speed to scale my torque. Let me have it! I needs to know! Thanks in advance. Attached is the file. rotationPhysics.hipnc
  23. Hello, So I need to create an activation trigger for a multisolver, that is based on impact with a certain object. I know it involves a script solver, but I've reach a dead end on how to detect impact based on a certain object. I know my impact data will say when it impacts what object it impacts with, but I need to save this data going forward and decipher it probably with a dopobjscreatedby("X"). Attached is the version that shrinks the geo based on the script solver activate_onFrame is based on Frame # 34. It hits a random object then hits the ground. I would rather call out if it hits the ground then shrink so I don't have to babysit the sim for activation of this. Thanks -Ben Edit: Attached the example scene file, duh! ShrinkScene.hip
  24. Hi, I've got a scene with some particles inheriting their velocities from sops. I can't seem to get the particles to match positions with a duplicate set of points which have just been displaced along the sop velocities. What am I missing? (Please find my scene attached - created in Houdini 13.0.288) Cheers, Tony pops_velocities_test.hip
  25. Hello, I'm looking for the equivalent to the pops nodes rotation, velocity, and attribute in dop pops, trying to simply convert a H12 to H13 setup. Not sure if this need be an RFE, or if there is an equivalent already there. Thanks -Ben