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Found 135 results

  1. 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
  2. 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!
  3. 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.
  4. 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
  5. 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
  6. 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?
  7. 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?
  8. 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.
  9. I'm building a relatively complex Vellum DOP setup using multiple objects with different constraint arrangements. The issue I'm having is my usual Achilles heel with this sort of thing: modifying attributes and values mid-sim. My specific issue is that I have a Vellum cloth object that is using the Pin to Target constraint option to follow some geometry I'm animating in SOPs. I created a point attribute for the target weights and that's working fine. My problem is that around halfway through the sim I want to animate down the target influence for this specific pin constraint. I have partially solved the problem using the Vellum Constraint Property DOP and animating the "Remove" value from 0 to 1 at the frame I want the pins to disengage. This works nicely as long as you're careful to select the specific constraint geo in the Group field of that DOP it will work. It's working so I'm going to get through this project using this method, but I'm having a really hard time figuring out how to modify my existing per-point constraint values using these fields. My questions: There are a bunch of specific vellum constraint attributes represented like Stiffness, Damping Ratio, etc. in the Vellum Constraint Property DOP that I can play with over time. Are these scalars that multiply by the point attributes I already have? Or are they values that will override the ones I've already set? Assuming they are overrides, is this why the VEXpression toggle and field is there? If I do something like "stiffness=stiffness*(fit($FF,50,100,0,1)" will this remember the original value of stiffness or is that being reset each frame? There is also the SOP solver methodology where I can modify the definition of the Constraint Geo over time. I can always fall back on that but it's also kind of tricky to setup. Hoping for something simple and effective that can just be wired into my DOP network. I really rely on the Sidefx example files to guide me through a lot of these setups, but I find that these kinds of constraint modification setups are in short supply. Would love to know how everyone handles this sort of thing. If anyone has guidance on this sort of thing, let's discuss. Thanks community.
  10. Why does the attribute noise on velocity cause the whole simulation to go in one specific direction? and I'm not even able to change the direction, it's always the same. Here are screen shots with the attribnoise enabled, then disabled and the pyro solver settings. How do I tell that attrib noise not to go in that direction? I've changed its settings but it doesn't change direction. Even if I change the source geometry behind the smoke, even if I rotate the source, the direction stays the same.
  11. I'm trying to understand how to assign colliders to objects in a vellum simulation. For example, I would like to add a collider that only grains will collide with, while the collider is ignored by other objects in the simulation. This helpful solution shows how to accomplish this with a dopnet setup. (A screenshot of this approach is below.) However, I don't know whether it's possible to send the output of the dopnet to Vellum IO and Vellum Postprocess. Is there another way around this? Or perhaps a way to control collisions from within the vellum sop solver?
  12. Kill particles by distance

    Hi all, I'm trying to come up with some vex to use to kill particles in a sim when they have traveled a certain distance from their birth location. I have mother particles that last one frame and i'm using a pop replicate to spawn new splash particles from them. What i'd like to do is store the position of the mother particles and subtract it from the position of each replicated particle every frame to get the distance, then set them as dead once this has passed a given threshold. Extremely limited VEX experience here, so if anyone could give me some kind of starting hint/snippet that would be amazing Many thanks, H
  13. Hi all, I'm trying to come up with some vex to use to kill particles in a sim when they have traveled a certain distance from their birth location. I have mother particles that last one frame and i'm using a pop replicate to spawn new splash particles from them. What i'd like to do is store the position of the mother particles and subtract it from the position of each replicated particle every frame to get the distance, then set them as dead once this has passed a given threshold. Extremely limited VEX experience here, so if anyone could give me some kind of starting hint/snippet that would be amazing Many thanks, H
  14. Transfer Low to high sim - vellum

    Hello, i have a vellum source emitting a low res model every 10 frames. How can i exchange the low res output with the high res version? this is my setup, i am working on Houdini 17
  15. Hello everyone, I'm hoping this is a super easy one, and I'm just missing something simple. I'm reading in an attribute into a vellum sim, to use it as a falloff for some forces. The problem is it's only reading the attribute on the first frame. I'd like to be able to read in these attributes every frame, to adjust the falloff. I've attached the hip to illustrate the issue. Any help would be greatly appreciated! Cheers! AttributeUpdateDOPs.hiplc
  16. Hey all, it's first post here and new to Houdini so I appologise if this isnt the easiest to follow. I have been trying to create a robust system for controlling vornoi fracture points, their glue strength and a way of manually breaking constraints between points. Ive been following some tutorials piecing together relevant bits from each to try and achieve this. My current issue Im facing is that once I play the simulation and the constraints start breaking they start flickering back on and glueing parts of the object which have already been broken. From my undertanding I think the manual breaking of constraints which is conflicting with the remove_broken SOP solver within DOPs, but I can't figure out how to get them both to work together. Any help would be greatly appreciated as I've hit a brick wall with this. Ive provided my scene file - I hope it's all easy to undertand. Thanks. Fracture_v001_notworking.hiplc
  17. FLIP-Pyro Interaction Tutorial

    Hey folks - long time lurker joining the party with a tutorial showing a workflow for integrating the FLIP and pyro solvers, allowing for bidirectional interactions. I cover a few other tips and tricks along the way, so I hope you find it useful! Hip file attached (and linked through from the video). flippyro_diffusefx.hiplc
  18. I'm hoping this is a fairly simple one, but I'm beating my head against the screen which doesn't seem to help ;-) I'm working on a scene with a large number of various bottles and trays in a simple dynamics simulation. All bottles can be simulated as tubes, all trays as boxes. Simple enough. What I can't seem to work out is an efficient way of instancing high-res bottles, trays etc over the proxy geo. My first idea is using an instance SOP with a 'DOP Import' node to give me the positions, using 'create points to represent objects', then varying the path with s@instance="obj/bottle1" etc; but although the points all seem to transfer fine, with data intact, the instances don't follow the point positions properly - the instances all come in at the origin of the sim and then explode out from there. I'm guessing I need to correct the first p/s/r values for each instance... but that's where I've ground to a halt. Hope someone can help! I'll upload where I've got to if that helps. Cheers -Chris
  19. FLIP substeps for fast moving boat

    Hello dear odforce users. I have a question regarding substepping with fast moving colliders. I have a catamaran speed boat which is driving in a straight line at roughly 60km/h. I added some procedural animation to the boat with the help of the ocean spectrum, that drives the wavetank, and CHOPs. Currently the simulation uses 6/8 Substeps on the FLIP Solver and the Solver has access to the sub-frame collision geometry. The problem I'm running into is that the trail left by the boats keels has visible stepping in position and velocity, which causes tendrils to shoot up in the boats wake. This doesn't look good together with motion blur. Should I increase substeps further to get rid of the stepping by brute force? Work out a whitewater setup to mask this behavior? Or is there anything else you can recommend in this case? I'm thankful for any suggestions. P.S. Unfortunatly I can't provide any scene files
  20. Hello, I'm sure my title for this post could be clearer, so for visualization purposes, say I have a field of discs that are RBD Packed Objects on the XZ plane, and above them there's a sphere with gravity: Normally the sphere would fall onto the discs and the discs would act more or less like a ground object, but I'm trying to have the discs raise up depending on each one's respective distance to the sphere. So far I've found that the positions of the discs (RBD Packed Objects) can be controlled in a sop solver within the dopnet, but I have no idea how to reference the position of the simulated geometry (the sphere) to inform the discs' positions. Can anyone show me the way? My ultimate goal is to eventually replicate the desired effect with the sphere being a vellum object.. would that require a different workflow? Here's my setup so far that may or may not save you a minute: sample.hipnc Thanks for taking a look!
  21. Exploding vellum grains

    Hi guys, I'm currently trying to setup a test of vellum grains with loose sand and clumps falling from 1m down on a pighead-collider (grain size of around 0.001). I did lots of tests already but can't manage to get a stable result where the clumps (more or less) keep together on impact. They stick together mid air, but as soon as they hit, explode and spread in numerous pieces. Scene and sim is according to realworld scale. Settings I use are all default but: Common-Tab: Substeps 12 Constr. Iterations 2000 (That high since I was told it needs to be roughly the amount of grains you want to pile up, and having grains around 0.001 in size makes pretty huge stacks.) Static Friction 0.75 Dyn. Friction 0.15 Advanced Tab: Repulsion: 1500 Attraction weight 1 (weighted/multiplied with a point attribute (0 to 1 values) that defines loose sand and clumps based on a noise pattern.) Attraction 100 It would be very cool if someone help me figure out why this is not working. Any hint or even a example-scene is much appreciated. Thanks in advance for your time!
  22. Emit Time Range till End Point

    Hey Guys, i got a question. I got a vellum sim and i am emitting every 8th Frame one sphere into my sim. I did it with -> $FF % 8 == 1 but now i want that emission just between Frame 1 - Frame 48. So between F1 and F48 i want every 8th Frame an emission. How can i get this with an expression? Cheers and Thanks!
  23. Finding the Min/Max values in a field?

    I am trying to figure out how to get the converse of a field, mathematically. I am attempting to blur a Cd field in using a Gas Blur microsolver. I have some mixed results, but I want to get some finer control over the radius, namely that I want it to blur more as it slows down. I have used the gas analysis microsolver to get the speed field by taking the length of the velocity, but I can't figure out how to get larger values to be in the lower speed areas. Obviously I would love to use a fit to invert the values, but I am struggling with an elegant way to get the minimum and maximum values for a given field. I could easily just do a loop in a wrangle and get the min/max values that way, but that is going to be extremely slow as this is a very large, dense simulation. Is there a simple way I can get the min/max values in a field so I can use fit(@speed, min, max, max, min) in a Gas Field Wrangle node to get the converse of my field?
  24. Vellum use imported restscale attribute

    Hi all, I can not get my vellum sim to use an updated restscale attribute. It is animated on sop level (see image 1) and merged into the sim in a sopsolver with Data Name set to 'ConstraintGeometry' (see image 2). The animated attribute is in the sim, but it is not used. I attached a simple example .hip. vellum_restscale_import.hiplc
  25. Hi Everybody, I've got a few (hopefully) quick question about Vellum Constraint Attributes! So I'm basically using the vellum grain solver, with a custom constraint network made in SOPs. I've been able to get what I think is correct behaviour by adding my own attributes for "type", "restlength", "stiffness", "compressstiffness" e.t.c However I noticed that there are some attributes that the Vellum Solver seems to add, such as "pts[]", "stress", "L" & "typehash". Not a problem so far, except when I add a SOP solver to my DOPs to dynamically add constraints these attributes are missing. I've been able to get my constraints to work by correctly setting the "pts[]" attribute, however do I also need to be working out the "stress" and "L" values? Are "stress" and "L" influencing the solver, or are they more like data out attributes? Finally, do I need to worry about the "typehash" attribute? I can't easily upload a scene while I'm at work but if you guys think it will help explain my situation better I can do it when I get home! Thanks in advance! M