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Found 90 results

  1. Hi there. I have a small issue going on. I have a source emitting boxes as packed rbds. The boxes have different sizes according to the pscale value and that attribute is stored in the packed prims in the assemble sop. When I use a dopimport to read back the points and copy boxes on them, pscale value is gone, it looks like the dopnet didn't store it. Usually this is not an issue because the static geometry is transformed with the transform pieces sop. But here there's this issue with the pscale attribute. I attach a very simple setup that shows the problem in action. Thanks a lot! packedPscale.hipnc
  2. So i have this sim and i would like to dampen or even remove the movement in the Y axis since it makes the concrete look light and weightless. I was trying geometry wrangle and anchor nodes, (not really sure how to use either), i wonder if there is a place where i can simply put a simple VEX line like @v.y = @v.y*0.25 or something similar. Can someone point me in the right direction on where can i do that and where should i plug such node in case there is a way. untitled.mov here is the Dopnet right now
  3. Hi- I'm manipulating objects in a sim with a sop solver, based on their dop object names. The simple case is to say, turn on or off the @active attrib in a bullet sim base on the object name. Right now I'm adding a string attrib with the name to the packed primitives on the SOP side, before they get made into an RBD packed object and checking that name the sop solver in the sim, using a point wrangle to make changes, etc. It occurs to me though that OBJID is and the object name are both available but I can't figure out how to read them while in the sop solver. I know I can use a function like dopoptions to get the name but that requires me to have the OBJID of the dop oject that the sop solver is working on and I can't figure out how to get that in the sop solver itself. In short, what node/expression will get me access to the object's name or id in the sop solver inside a dop sim? Thanks
  4. I'm trying to simulate cloth interacting with an animated file cache. The cloth sim is pretty much from the shelf tool and the collider was set with the surface collider shelf tool. the collider is poking through the cloth. im having trouble finding which parameters to change to stop the interpenetration. i've increased the substeps by a lot but this doesn't seam to have an effect. any suggestions would be appreciated.
  5. I may be missing something in the voronoi fracturing SOP, but I can't figure out a way to create clustering without causing fracturing on the geo. For instance. A standard brick will or just group of geo that clusters into groups using the scattering method so I could make the cluster groups bigger or smaller. I feel like I'm overlooking something so obvious, or maybe I have to create proxy geo that is clustered and test if the brick particles are inside of it to group them? Ah, now I've just confused myself. I hope a few of you have run into this problem and have some incite. Thank you :D!
  6. Hi all! I'm currently trying to find a way that I can control when an attribute on packedrbdprims coming into DOP's gets written to from the "Overwrite Attribute from SOP" box and when it gets written to from the bullet sim I have set up. I have a set of packed primitives with rotation animation on them being fed into a bullet simulation, I'm also adding an "active" custom attribute which is being used by a SOP slover in DOP's with a vex wrangle inside it to activate them when the value equals one. What I also want to happen is have the orient attribute on each packedprim update from the existing vaules from SOP's right up until the point when the bullet solver takes over and begins writing to the orient value. I know that I can add orient to the "Overwrite Attribute from SOP" box but what I 'm hoping for is a way to disable this function for each object as they become active rigid bodies, essentially adding to the orient values that exist on that particular frame and continuing with the sims values. Instead of having the sim take the orient values that exist at the first frame or continually updating those values as the packedrigidbodys are influenced by the sim. I know its poor form but I'm afraid I dont have the project file on hand to upload, sorry guys :S hopefully I can upload it next week if anyone needs to see it. Any help would be massively appricated! Many thanks
  7. Hi I'm new to Houdini and recently I've been getting into DOPs. I have a question I've been trying different things out in dops to see how they work, been playing around with the "Gas Match Field" node and found that it works quite nicely when both fields you are supplying the node with are from the same object Like on picture 1, both the "myField" field and the "heat" field are part of the same object and the node works just fine But what I can't figure out is how to make the node work when I'm supplying it with fields from different objects. On picture 2 "myField" is part of an empty object and the "heat" field is part of the smoke object, I tried to reference them via their paths like on the picture 2 but unfortunately it doesn't seem to work. Does anyone have any insight into why this may be, I can see how referencing field from different objects can come in handy not just for this scenario.
  8. Pyro Clustering Tutorial

    In this tutorial we will go over how to set up optimized pyro clustering with oriented DOP containers in Houdini given a piece of geometry moving through a scene. This process will lower simulation time and be more efficient when saving to disk because there are fewer voxels. Link to Tutorial -> https://gum.co/TqUNR The tutorial is free though, if you feel like giving me some support I'd be grateful !! We first go over how to get things set up quick and easy and in the second half of the tutorial we make further optimizations using VEX. We'll look at how to rewrite cluster points to do exactly what we need it to, which includes rewriting the resample sop using VEX. An intermediate tutorial for those looking to speed up their pyro workflow and learn some VEX. Includes the scene file! Hope to see everyone leveraging these optimizations in the future and squeezing in those extra few iterations before deadline! You can reach me at trzankofx@gmail.com for questions or comments.
  9. Hello everyone, I've been getting into DOPs recently and i just cant figure out something. I have a SmokeObject and an RBD object. They are both plugged into the Pyro solver. The smoke has a collision relationship with the RBD object, and the Pyro solver's option "Temperature Merge" is set to "Collision Interior". In order for the "Temperature Merge" to happen the RBD object has to have a temperature field. Now what i want is for the RBD object's temperature field is to be just like what the smoke's temperature is but subtracted by a number so that the RBD object is always cooling the smoke. I've Created a fog volume that consists only of value 1 voxels inside the RBD Object and value 0 voxels outside of the RBD Object. I'm planning on using this as a mask for the smoke's temperature field (multiplying these two fields) and then lowering the value for all the kept voxels. Now i don't know what is the best way of achieving this but i thought that I can bring in the mask field (the only 1 or 0 field) into the dop network using the "Sop Scalar Field Node" and then extract the temperature field out of the SmokeObject using the "Fetch Data Node", wiring these two into the "Gas Calculate Node" and then blending and doing post subtraction in there. I don't even know if that is the right way to do it, but anyway once I connect the scalar field (the temperature mask, brought in from sops) into the gas node everything is ok. Once i plug in the data (SmokeObject's temperature field) into the gas node it reports an error saying that the connection to the fetchdata node is the wrong type. How could this be? Both the "SopScalarField" and the "FetchData" nodes output data, how come that the gas calculate will accept data coming from the "SopScalarField" node and not from the "FetchData" node ? I've been trying to resolve this for a while now, if anyone could help out it would be greatly appreciated
  10. RBD to unreal

    Hey all Could anyone point me in the direction to get a rigid body sim into UE4, I've got the Sim (it can be super simple) and I'd prefer FBX. Ideally I don't want deforming geo. The closest I've found is this workflow but it seems like the code isn't maintained. (This isn't mine) LINK https://vimeo.com/124874315 https://www.orbolt.com/asset/LaidlawFX::RBDFBXExport::1.0 I wanted to know if there's something I'm missing. Thanks once again in advance. Brian
  11. Is there a way to calculate the angular velocity from spinning points that only hold "N" "v" and "up", without using the trail SOP?
  12. Happy holidays everyone seen this question here before but tried all the suggestions with no results, I am manually deleting the constraints via attribute transfer. but some of the glue constrains reappear and stops some pieces mid-air. using packed primitives. am i missing an option somewhere? or did I miss a step?
  13. I am trying to create a simple scene where balloons are tied together to an object using wires.(like in the movie “UP”).. Im having balloons as packed RBD object and the parent point(where balloons are tied) as a separate rbd object. and having wires also into the DOPnetwork as wire object.. Initially I dint simulate the wires but used the wire lines as a constriant network from SOP and made a spring constraint between balloons and parent using the wires as a constraint net, And It worked Perfectly. Now I am turning the wires into wire object and trying to constraint the top of the wire to the balloons and bottom to the parent object, I am having matching @anchor_ids on wires and balloons.. But It doesnt work properly. If someone can explain how to constraint wires with rbd , It will be very helpfull for me.. And if someone already have a scene file for related to this please share it , Thanks a lot in advance..
  14. I'm pretty new to Houdini and i've seen the "Active" attribute come up a few times in tutorials. I searched but couldn't nail down exactly why and where this comes from in Houdini. I get that it seems to pertain to DOPS and Glue constraints but I wasn't really clear on it all. I've seen people create it in sops and use it later in dops to activate things. My questions are: Is the "active" attribute a native attribute that nodes in DOPS looks for? Does it control all dynamics/force/glue or can you specify? Really any general info on it is appreciated! Thanks!
  15. This has been really getting on my nerves the past few days. I'm just messing around with particles and their attributes, connecting them to a Principal Shader for practice. I can get Emission to turn on(emitillum), I can control the intensity(emitint) but I cannot for some reason figure out how to control the Emission color. I know that Emission Color's parameters are: emitcolorr emitcolorb emitcolorb In my example I did a lowish-res flip sim and connected the velocity to Emission Intensity (@emitint = @v;) for example. However, When I colored my particles using a ramp and using the velocity channel, I figured I would try: @emitcolorr = @Cd.r ...and so on for Green and Blue. But, this did not work. I feel like I'm dancing around the answer but not able to find it after searching. I wonder if anyone else has run into this? Best, Stark!
  16. This has been really getting on my nerves the past few days. I'm just messing around with particles and their attributes, connecting them to a Principal Shader for practice. I can get Emission to turn on(emitillum), I can control the intensity(emitint) but I cannot for some reason figure out how to control the Emission color. I know that Emission Color's parameters are: emitcolorr emitcolorb emitcolorb In my example I did a lowish-res flip sim and connected the velocity to Emission Intensity (@emitint = @v;) for example. However, When I colored my particles using a ramp and using the velocity channel, I figured I would try: @emitcolorr = @Cd.r ...and so on for Green and Blue. But, this did not work. I feel like I'm dancing around the answer but not able to find it after searching. I wonder if anyone else has run into this? Best, Stark!
  17. Im stuck at this point in the particles debris. So my structure collapses to the ground with a typical rbd sim. But when i emit debris particles from them, my particles seems to stop falling after colliding in the top floor of the building and just stays there like a sleeping object. I am using vdb from polygons for my collision geometry which is the geo from the sims. Is there a way to tell the particles to not go still and fall along with the falling building. Thanks alot.
  18. Animal Logic's Matt Estela is our new GridMarkets Featured Houdini Artist! He manages to explain a complex and confusing topic such as DOPs in simple and efficient terms - check out his amazing tutorial here.
  19. I thought I was losing my mind when I first ran into this because I thought I was just having a brain fart. But, When using the "Voronoi Fracture Configure Object" I can't seem to only have particles emit from the newly created inner surfaces. I attached my scene file to this post. I know that if I do the fracturing (non-dynamic) in SOPs, I get the inside and outside group. I feel like this is something that is super obvious and I'm just not seeing it right in front of my face. Any help would be much appreciated! Thanks!
  20. DOPs Initial spin at event.

    This has been a very hard search to find an answer to. What I'm trying to do is add an initial spin/rotation to a DOP object. I attached a simple scene of a torus that has an initial upward velocity and then just falls to the ground due to gravity. Essentially, I'm trying to give it a "punch" that will cause it to spin - but not perpetually. A good example would be if you had an object that hit "glass." Although the sim would be physically correct, to add interest it would be nice to add a little spin force to the shards of glass on the initial impact. I can't for the life of me find a way to do this in DOPs. I'm sure I could be overlooking the most obvious parameter, but it's also Houdini and sometime the simplest task takes some finagling. Any help is appreciated! DOP_spin.hipnc
  21. DOP POP curl noise question

    Is there a way to freeze the transforms of a curl noise in a DOP popvop? I am running a point sim and my source emitter object is animated and rotated in world space. When the points emit, the curl noise added to the point position slides. I'm really not sure what to do in the popvop to freeze the curl noise. Ive tried using a popforce, however the curl noise does not seem to create the same shapes that the popvop does. Thanks in advance.
  22. DOPs Process Sequence?

    I have a simple DOPs setup where I'm trying to understand the processing sequence.. While watching the Geometry Spreadsheet, I move 1 frame at a time: Frame 1: Field A is created (Field B visualization is also created) Frame 2: Field B is created (Using Gas Match from Field A, then a Field VOP creates volume data) Frame 3: Field B is now properly visualized. My question is, is there a way to get Field B's visualization as soon as it gets created (at frame 2)? Currently, visualization for Field B only activates on frame 3. houdini_solvers_study.zip
  23. Hey there, I am currently trying to simulate a (single) falling fir-branch like the ones you can see in this image: I would like to use a wire solver for that, but I am having a hard time to make the needles stick to the branch. How would you go about that? Desired setup: * branch as wire obejct (soft body behavior when colliding) * needles as wire object attached to the branch (soft body behaviour as well) * gravity in place, falling fir-branch, colliding with a ground plane. I tried the "Attach wires to surface" shelftool, but that attaches the selected wire points only to existing points on the branch-geo (which is low res, with just a few points). I would like the needles to be independent of the branch geo so that I can have a rather lowres branch geo (tube, less subdivs), and lots of needles. I would like to attach them like it is possible with folicles in maya, having them stick wherever they are on the surface, not having them stick to one of the input points on the fir branche geo. Using the point attribute "pintoanimation" or "gluetoanimation" also does not work. Doing so, the needles jitter around as soon as they are not in line with a points of the underlying branch geo. Do you guys know any solution for that? Thanks in advance for your time and help! Cheers, Philipp
  24. I started a thread a few weeks ago about using scattering and Voronoi points to create clusters from multiple objects. That thread is here: Clustering without fracturing? Luckily, that was solved after much confusion. However, now that I have that rendered with a few other stuff thrown in, I got curious about secondary fragmentation using those same clusters. The problem I'm running into is when I'm in DOPs and I add a voronoifractureconfigureobject. When there is collision's, there are no fracturing. But, If I un-cluster the bricks and constraints, the bricks will fracture as expected. I attached a photo and my file to the thread :D. Thanks! building_frag.hiplc
  25. access object data in dops

    Hey, I am trying to access/ passing data from different objects inside dops. Imagine obj0 has data called "impacts", which are a bunch of points and I like to pass this into obj1. Inside a gas particle to field wired to obj1 I like to access "impacts". I thought it would be as easy as putting down obj0/impacts into the particles parameter. But that did not work. The only way I found is copy/apply impacts to obj1 via fetch data dop, which I feel is a bit redundant. Any advice? Do I have the syntax wrong? Cheers Sebastian
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