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Found 120 results

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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!
  6. 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!
  7. 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!
  8. 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?
  9. 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
  10. 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
  11. Ran into an issue while learning DOPs. After having setup Vellum in SOPs I'm trying to import the setup in DOPs. At first everything is fine and dandy, but if there is a Transform added to the geometry on object level then only the GEO that's imported into DOPs network is updated. The Constraints are still in their original position. Is it possible to update Vellum constraint location when the object node is transformed? Adding a basic example file with the issue. test.hipnc
  12. I want to create hanging wires using DOP wiresolver, I followed this tutorial on Youtube: https://youtu.be/fkJOzHY8fOo But in my setup the simulation is not starting. Please help Hanging wires.hip
  13. hey ya'll, i'm trying to animate the restscale of each emitted hair strand based on age but i'm currently stuck because "@restscale" is erroring out on the vellumconstraintproperty inside the dopnet. any ideas would be great! thank you! chris anim_rest_scale_age_v001.hip
  14. RBD's and SOP Solver

    Hi peeps, I'm using the SOP solver DOP to change my geometry overtime from one sphere to multiple spheres, however, when the geometry changes to multiple spheres it's still behaving like just one object instead of individual spheres and I can't figure out why! Any help would be much appreciated and I've attached the troublesome scene file. Also, I used the RBD Fracture object for this instead of the RBD packed, because I couldn't get the results out of the SOP solver to work with RBD packed object. I unpacked the geo in the SOP solver and repacked the output with the name attribute and it wouldn't work, so also, if anyone could shed some light on that as well it would be much appreciated. Thanks. RBDs_SOP_solver_testing_01.hip

    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
  16. Vellum string constraint break

    Hi everyone, I'm currently having trouble with breaking a vellum string object in half. The idea is to make a saliva strand that's stretching before breaking in the middle. Currently i have a line that's vellum string, attached at the top point via "pin to target" constraint to an animated object. (string constraints are SOP level, fed to DOP node, with "pin to target" constraint done within the sop solver "forces" subnet) Sim follows the object, and i can break the "pin to target" constraint itself via the vellumconstraintproperty node, set to the group with the top point. I tried various ways to group the centre point of the line, and keyframe another vellumconstraintproperty node, but it doesn't work. Can anyone enlighten me on the proper way to break string constraint points in a keyframe-able way instead of just using stretch stress? Thank you very much in advance!
  17. Hi guys, I'm trying to save out a file cache of a simulation and then import it into a different DOP net to use it for collisions with particles without the particles changing the file cache Geo. Any help would be super appreciated.
  18. slicing object while simulating

    I'm trying to slice an object during a rigid body simulation. imagine a fruit falling through a grid of laser beam. the object is supposed to be sliced in multiple pieces. i can't pre-crack the geometry as the fragments depend on how the object hits the lasers. like this,
  19. Help with multi solver

    Greeting all, I am trying to wrap my head around the multisover in dops. I have a sim of a plank breaking. I have upacked the sim and placed a debrissource node after. I then copy cubes onto these points and point a pop source to them. I have a packedrbd object running into the multi solver which runs a pop solver then a rigidbody solver. It kind of works but when the cubes hit the ground the shake and jitter and generally misbehave. Any Insite into why this could be happening would be greatly appreciated. I have attached a sample file. Cheers! B plank_troubleShooting_v04.hipnc
  20. Hi. I'm struggling to solve what should perhaps be an easy problem; - Release a fixed number of points with an animated point attribute, using POP's. Here's what I'm trying to do; - Take a packed object of fractured pieces. - Pass it to POP's. - Treat all objects as static as first. - Then release each object using POP's, using an animated point attribute. - Use transformpieces to animate the packed object. I'm able to do this with the RBD solver, but it takes an incredibly long time. I don't need the accurate collisions of RBD, but really need the speed of doing this with POP's. Below is a side-by-side scene showing the setup working if I animate the particles using @P, versus my setup that doesn't work because it relies on an animated attribute that doesn't get passed through to the points (because they are born on frame 1 and have fixed attributes). Help really appreciated! clinton release_particles_from_animated_value.hipnc
  21. dynamic bones

    I'm working on a project where I need to hand animate a snake-like character doing spirals and twists. Investigating approaches, I came across this video, where the guy basically gives a bone chain wire dynamics, and is able to get some really nice overlapping tail motion, just from animating the root of the chain. At 9:00 of the video he starts to add dynamics, and you can see the animation effect I am trying to achieve at 12:50. My goal is to find the easiest way to get overlapping tail motion, by animating just the root. So far I'm just trying to get a wire to behave nicely and not explode from a simple sine wave animation, nevermind getting the bones to move with it. Any rigging experts have advice on how to approach something like this in Houdini? Thanks!
  22. How to Transfer UVs to Vellum Grains

    Hey, has anyone tried this yet? In the past when creating FLIPs I would normally carry UVs through DOPs using an attribute promote to carry the UVs from vertices to points, but it seems like this is not working when applying the same methodology with vellum? Please help!
  23. Colored Smoke with CMYK

    Last week a guy asked in the brazilian houdini group, in facebook, how to simulate colored smoke. I believe there are lots of hip files with this kind of effect, but while thinking about it, it came to my mind the possibility of using CMYK instead of RGB, since cmyk is more suitable for mixing colored things other than light. I couldn´t spend more time testing it or improving the file, but it seems to work, so here´s the hip file. colored_smoke_V002.hip
  24. What XSI | ICE "Project a vector" equivalent on POP/VOPS? reference: http://download.autodesk.com/global/docs/softimage2014/en_us/userguide/files/iceref_Project_Vector.htm the node on XSI returns 3 things: RESULT LENGTH VALID any ideas? thanks in advance!
  25. Import Pop Field into SOPS

    Hi all I'm looking to replicate a Houdini sim that I have inside Unreal Engine. I would like to export my vector fields as flow maps that can drive Unreal's native particles so that they still remain interactive (collisions, emission, etc). I'm having trouble accessing some of the native POP fields outside of DOPs. Can anyone explain how to import a POP field such as pop axis force out of DOPs into SOPs so that I can then export it? Thanks! Nick