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Found 110 results

  1. 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!
  2. 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!
  3. 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.
  4. 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!
  5. 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
  6. 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 :-)
  7. 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
  8. 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
  9. 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
  10. 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
  11. I use sop solver for deform my spheres in DOPS, but they don't interact together correctly. Help me please!!! spheres2.hip
  12. 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
  13. 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
  14. 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.
  15. 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
  16. 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
  17. With the new dynamics workflow in Houdini 13, there seems to be a tendency to simulate many things in the same DOP network. In fact, this is the second time this issue has come up, and only the second project in H13. Imagine RBDs falling into a flip simulation, (ice in water if you will), and you want to write out both the ice geometry and the water simulation geometry (flip points). What I ended up doing in this case, is write out the .sim data once, then extract the geometries and write those out in a separate process. This technique was clunky, as it resulted to a file node in-line in the DOP network, leaving a huge room for error. The second case deals with DOP particles, created using the new H13 particle workflow. I have an RBD simulation of fractured geo, and I would like to add some small debris particles and smoke. Should I do the sims in stages? (RBD -> particles -> pyro) While it makes sense to do the pyro as a separate stage, since it would slow down the iterative process and dialing in the behavior of the RBDs, it would be awesome to be able to sim it once, producing 3 separate geo sequences at the same time. Does anyone have thoughts or solutions to this? Thanks in advance. Gosh
  18. Cannot get wire to collide properly

    Hi, I'm trying to create a wire that is being pulled through a slit. But I'm unable to set the collisions properly so that the wire is able to go through it. I've checked the wire with and also the collision guide geo. I have really no clue what I'm doing wrong here. WireThroughSlit.hipnc
  19. I'm beginning my exploration of dops and I wanted to take a simple poly sphere, partition it into groups where each face is in its own group, then feed that into an rigid body sim to have it shatter against a static ground plane. Attached is a simple scene with my attempt to do this. The only issue is that some faces of the sphere remain unaffected and others pass through the floor. I'm not sure if I'm partitioning incorrectly or if my collision setup is incorrect. Thanks for your time sphere_shatter.hip
  20. 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.
  21. Multple Custom DOP smoke domains

    I have a few dozen smoke simulations that I want to run in a single DOP. They have separate domains, and I'm trying to find a way to have a single Smoke DOP generate N smoke containers, and assign each container to a seperate domain bbox. I eventually want to assign custom division sizes to them as well. Extra credit for being able to assign non-axis aligned domains.
  22. Hey folks, I'm having an issue when trying to dynamically fracture a glass tumbler object. Check out the quicktime attached to this post. You can see that the glass hits the floor, the object is fractured, but they immediately bounce back up. What I would expect to happen is have the pieces continue their movement down into the ground, but I can't find a way to get this. I've tried adjusting the Pre/Post Velocity Bias on the fractureparms node, but that doesn't seem to help. Does anyone know what params I should be looking at? Thanks for any help. Sid badsmash.mov badsmash.hip fixed_tumbler_EXP.obj.zip
  23. multiply collision with density

    Hi everyone I'm using a smoke simulation where a simple source is dripping smoke on a collision box. The collision uses the sourcevolume method, so I have the SDF collision available. I'd like to create an additional field which is nothing else than the result between the multiplication (intersection) between the collision field (after gassdftofog) and the density field. Basically I'd like to use this resulting field into a pyro symulation (a separated sim) as fuel to emit fire. The result would be that some fire emits from the locations of the cube where the smoke is dripping. I used a match field to fill a field "collisioncopy" scalar field, and filling it with the content of the collision sdf after converting it to fog. Then I used a gaslinearcombination with the folliwing calculation collisioncopy=collisioncopy*density The problem i have is that obviously the collision field and the density field are mutually excusive so the result is an empty field. My question is: is there some quick and dirty way to "expand" a certain field by a certain amount of voxels (in the direction of the gradient of its density for instance). This way i would be able to have an overlapping area between my collision field and the density and I could calculate the intersection between them.
  24. Kill Particles on Rest

    Hi everyone, I am trying to create impact dust when a piece of rock hits the ground. To emit particles I used attribute transfer to create the source from which the particles are emitted and everything is fine to this point. However, I would like the particles to stop emitting when the source geometry stops moving and I can't figure out a way to do it without keying the activation value. Thoughts? Please see attached hip file to get a better idea. Thanks. RnD_Impact_Dust.hip
  25. In the example video/hipfile, I have a piece of candy, which is three rbd objects constrained together. Is there a way to do that in DOPs? I know you can "emit" rbds via some expressions in the creation frame parameter, but that doesn't take care of the constraints. Can we make a debris gun this way? Thanks! rbd_debris_gun.hipnc candy.mov