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Found 152 results

  1. Hello all, I'm looking to do some basic volume displacement using dual rest (something I've done before in the past), however I'm stumbling at the first hurdle now, when revisiting it a few years on: I cannot get a working rest_ratio and rest2_ratio out of a pyro sim. I could calculate it manually using the frame offset and blend length params, but I seem to remember simply being able to grab it from the solver. I have initialized the rest field in the smokeobject DOP, as well as dual rest mode in the pyrosolver advanced tab, however the ratio detail attributes don't appear to move. Looking inside the sim at the smokesolver_build2/record_sim_settings_to_initialization_data script I can see that the ratios are being correctly calculated, however this isn't being exported properly when I lay down a Dop Import Fields SOP. I've attached a really basic hip file. pyro_dual_rest_ratio_not_working.hip Can anyone help me? edit: using 18.5.633 Thanks in advance.
  2. I have an alembic with a lovely bit of movement happening, lying down on a ground plane. I'd like to make parts of it floppy, which I can do with vellum and a pin to target with an attribute that scales the pin stiffness so it's lower on the floppier parts. No problem there. The part I'm not able to figure out is this: I actually want to hang this up by one of the floppy bits, but still be able to use the shivering/shuddering from the target animation. The target animation is apparently evaluated as absolute coordinates, rather than deltas of a rest mesh, so even with the floppy part being hung up, the pinned parts are still lying on the "ground"/seeking the actual point locations of the target. Is there a way where I can get it to evaluate the target so that even if some of the animated bits drift (and move some of the not-quite-100%-pinned areas) the vellum will incorporate the source object's animation, but at it's new simulated place? Thanks for any help!
  3. Free video tutorial can be watched at any of these websites: Fendra Fx Vimeo Side Fx Project file can be purchased at Gumroad here: https://gumroad.com/davidtorno?sort=newest
  4. Deforming texture maps in Dops

    Would the deformation of texture maps work DOP networks?
  5. Hi Doing a vellum coiled cable sim and while I'm happy with the feel of it I've noticed I have some spinning close to pinned points, instead of bending. Is there a way to avoid this? Video shows the sweeped curve and then it shows the group used as pinned. phone_coil_cable_spin.mp4 I've noticed that vellum does not transform the input geo attributes (am I missing something?) so instead I used a point deform to preserve the sweep's orientation. Works well for most of the curve but not great on the tips. All constrains are super stiff so the coil shape can be maintained, so this could be the cause of the geo not bending but twisting. Still I wasn't expecting that twist. The Settings I'm using on Constrain and the Solver are below. Let me know if there's something to consider to avoid this behavior or to have Vellum transform input attributes. Thanks.
  6. Free video tutorial can be watched at any of these websites: Fendra Fx Vimeo SideFx Project file can be purchased at Gumroad here: https://gumroad.com/davidtorno?sort=newest
  7. I have a basic dops ( vellum to be specific) and i want to add elements dynamically to the sim. in the example > case1 , i create an random line and add it as a vellum hair into the sim .. and this seems to work. case2 and case3: i want to access the current frame of The Dops sim, and i create a line from a fixed point to a point on the mesh( think lightening ) .. but doesnt work. cant seem to access the current mesh and create a line(s) and adding it back to the sim.. any tips and pointers would be appreciated. thanks sideFx.hipnc
  8. Geo appearing twice in Dops

    hi guys, I have a vellum balloon constraint on my geo. Until there, everything working ok when I press play. I have added an Attach To Geo Constraint inside the dopnet and now, my geo is doubling up when I simulate. One of them behaves with the added constraint and the other one without. Whats wring? Tx
  9. Vellum Pressure

    Hi, I wanted to ask about some of the hidden intricacies of vellum pressure. In particular I recently found out about the @pressuregradient attribute that determines the direction in which the object expands as pressure is applied. I wonder: How is it determined? I suspect something to do with Normals, but then when I visualise the attribute it tends to always have a rough relationship with {0,0,0} - why? This leads to strange inflation especially if an object is off-center and then it trends away from the origin, as opposed to away from its center of mass... Can it be manipulated in the solver? It would be nice to procedurally predetermine the inflate direction, although I'm not sure how to access or manipulate this attribute. Can it be manipulated per frame? If I have multiple objects that start in a rest position and their inflations happen one after another - one ball moves other balls out of rest position for example... Then once the ball that has already been moved starts to inflate, is it computing on the pressure attribute given at the start of the solve, or the one at it's current frame number? I could probably word these questions better and I do apologise, but at the moment it seems I have run out of places/videos to read/listen to. Thanks a lot for your help! Cheers.
  10. Hi. I am trying to make a simple HDA which will drop down an asset on another asset. It works fine inside Houdini but it doesn't work in UE4 or Max. What is wrong with current setup? drop_dop.hda
  11. 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
  12. Grouping DOP objects by Impact?

    Hi, First time posting here and relatively new to Houdini, so please forgive any poor use of terminology etc. Basically I want to group DOP objects, specifically RBD pieces, when they are impacted by another object. I want to do this so I can add gravity to each piece as they are impacted. When I look at the geometry spreadsheet I can see the Impacts data appear, but I don't know how to then group these objects by this. If it helps to visualize what I mean, I've made this puzzle globe made of 500+ pieces, and I'm throwing this ball at it to break it apart. I've got my sim working well enough, but currently gravity is not acting on any of the pieces, so when the ball hits, it's breaking the pieces apart but they are acting as if in zero gravity. So now I want to group this pieces as they become impacted either by the ball, or the pieces next to it, so hopefully by the ends all of the ball collapses. Thanks for any help, Alex
  13. Vellum Collision Problems

    Hello! I am trying to deepen my understansing of vellum by building the solver netowork myself. I have hit is very enfuriating sustuation were my character litterally walks out of her pants. When I use the sop based solver this dosn't happen. I am sure I am missing something but it seems most things I have tried are giving me the same result. I am using an almebic cache for the collider, and cloth geometry brought in from Marvelios Designer. I am using an collision source node to generate a vdb for collisions, and using a staticObject set to “Use Volume Collision” and “Volume Sample” for division Method. Here is what I am getting
  14. I'm trying to create a Python UI state that returns the currents fields in a DOP network. I want to query the fields and then store there values so that I can print it in the viewport. I can find all the python documentation to get the fields themselves, but I can't seem to find out how to get the values stored in the voxels. I know it can be done in SOPs, but I really want to do it directly in DOPs. Is this possible? FYI, just using a simple Sparse Pyro Shelf tool for my testing. I want to query the density and temperature fields and calculate the maximum value stored in those fields. Thanks!
  15. Finished my first tutorial, hopefully you find it helpful learning Houdini!
  16. save particle velocities every frame

    Hi All, TL;DR - How do you save particle velocities each frame to feedback into a sim? I'm working on a particle effect for rain on a window. Currently adapting a nice example from Toadstorm. I've made some changes to his setup. He has new particles growing over time and becoming droplets past a certain pscale, so i've derived mass from pscale to connect droplet size and speed, as the wind force i'm using to move them is not set to ignore mass. video I added a sop solver after the DOP to delete still particles touched by moving ones. And a popinteract and a popfluid to try and get the moving drops to coalesce and follow each other as they move down, but this has only slightly worked. Ideally i'd like to write the velocities of the moving drops into a volume which could then come back into the sim the advect the particles, or some other technique that follow make it so that new drops hitting and existing trail would follow its path precisely, and add a little to their speed and size. I presume I would use a sop solver inside my DOP network for this, but no clue beyond that. Any advice much appreciated, H windowdrops-uv3-w.mp4
  17. Hey, I've been stumped on this for a long time now and cant find any more useful resources online. I've been trying to dynamically add vellum patches over time for a project of mine. In the attached video you can see my current result, which is done by switching between the sopsolver that creates the golem, and the vellum solver that makes them go stringy. Ideally I'd like for vellum to take over for each worm as soon as the sopsolver is done growing it, thus on attribute presence. Hopefully someone can give me a point in the right direction. Thanks in advance! Wormguy.3.mp4
  18. I have a vellum cloth object set up in DOPs. I want to add an animated pin to target constraint. I can get this working in vellum solver SOP just fine, but I can't figure out how to set it up inside a dopnet. I've tried setting this up multiple ways, and I'm not sure what I'm doing wrong. (HIP and screenshots attached.) I would also like to know how to specify target geometry in DOPs. dops_pin_example.hipnc
  19. Hi! I seem to be having a small issue with the 'transform pieces' SOP not working as it should. I have a mixamo animation that I have fractured and I use a 'point deform' to get the animation back onto the fractured geo. I want to use the 'transform pieces' SOP to convert my proxy geo to my hi res geo. Whenever I do that the whole thing freaks out. I have also tried freezing the pivot and copying it back to the 'dop import' points. Using the rest points does not work either. If anyone knows how to solve this problem then please let me know! Thanks in advance!
  20. Hit data in SOPs

    Hi, As the title says, I'm trying to make hit data in sops. To expand on that I have a sequence of points moving through a piece of geometry and I would like to create a point that lasts for one frame at the point of intersection on the geometry. Is this possible? I have a rough setup that uses nearestpoint and fuse, but the points I am getting are not accurate enough for what I am trying to accomplish. Mostly because the moving points are very fast and all have random speed. Any help would be greatly appreciated. Thanks in advance.
  21. hey... I had an idea of directly fitting in the whitewater source via a sop solver in dops as a post solve, is this possible? I have tried it. but with no luck, also by applying a compress fluid. before Im gonna send scenes Im just wondering. And about the experience. was trying to get some more fluids overtime to fill gaps like you would do in a sopsolver in dops thnx
  22. Hey all, I'm trying to play with a scene where I'm doing some explosions on a beach and I wanted to make sure I had all of the individual effects down before I started trying to do the large scene. I already figured out how I want to do the explosions with a sparse pyro, and I got the grains solver to behave how I want for the sand to be kicked up, but when I tried to add a pyro solver to the sand grains I got some weird results, so I went to make a simple example scene that would be faster to simulate and it started doing even worse stuff. My grains scene is giving me some really bad smoke that doesn't seem to be advecting and is only generating on each frame of my cached grains. Seeing this, I found an example file which was using a pops simulation to generate smoke, so I tried to apply what was in there to a simple test scene, and for some reason my sims are applying giant black box sprites to the particles before it even gets into the pyro simulation. If you have some advice on how to handle the dust from sand explosion that would be great. If you have any idea why I'm getting the sprites, that would be amazing as well. The files aren't the cleanest, but here they are. I am using GridMarkets caching and rendering for the sand file, so if you don't have their nodes you can just delete them and replace them with filecache nodes. SandboxPop.hip pyroFromParticles.hip
  23. Hi guys, I have a rigid body sim with constraint network, I want to access the previous frame and current frame data of the constraints (impact, forces etc) inside a sop solver in DOPs. Currently when I call the attribute in a wrangle from the relationship geometry node I don't know if it's current frame data or previous frame. How to get both the current and previous frame data in a wrangle in sop solver in dops?
  24. I'm looking for alternative workflows for defining attributes on a tet mesh for FEM simulation. Normally I would use intersecting volumes to define regions inside a tet mesh. But for my current purposes that would require producing some pretty complex geometry. The ability to paint these attributes would be simpler. For instance, it might be nice to be able to paint an attribute on the surface and have it penetrate the tet points at a given depth. (Though even if that were possible, I'm not sure how you would access deeply interior points that are not close enough to the surface.) What methods do you use for assigning attributes to a tet mesh?
  25. Bonjour, hope you all doing great. i can't get an alembic geo to be simulated in dops .. however if i made a simple animated geo with keyframe animation,i can switch from being active in dops and reading the animation but it doesn't work with alembic.. should i be baking the alembic to keyframes or how it works? Thank you.
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