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Found 86 results

  1. 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.
  2. Hi, Can someone help, and explain why after translating a cube up in sops, on the geometry node to postion a box on top of another box. then making it a RBD object. then simply add a deactivate object from the shelf tools, why my pivot and object change position when I jump into dops. Perhaps Im missing something silly here, anyone help please? thanks in advance.
  3. 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.
  4. 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
  5. 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
  6. Is there a way to calculate the angular velocity from spinning points that only hold "N" "v" and "up", without using the trail SOP?
  7. 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?
  8. 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..
  9. 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!
  10. 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!
  11. 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!
  12. 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.
  13. 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.
  14. 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!
  15. 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
  16. 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.
  17. 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
  18. 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
  19. 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
  20. 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
  21. I am trying to figure out how to spawn new wire geometry within DOPs as it simulates. I create the full wire shape at sop level and I then I animate the deletion of its points backwards, from a couple of points to the full set. Of course just by importing this changing geometry, the wiresolver won't re-import it on on every frame. I looked into combining a SOP solver and tried various approaches, but none worked so far. Deleting points in the sop solver didn't work. Then I tried deleting the primitive, adding or even copy (to aquire all the wire attributes) one point at a time and connecting them all with a new line primitive. But that didn't work either. Any ideas? thank you
  22. 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!
  23. Relative path to dop field

    I'm setting up a system to source into a smoke sim directly from particles, without having to add a "geometry" data field to the root of the dop object. It works great when everything is manually set up, I can create a reference to the "geometry" field which is nested under the microsolver. As an example, plugging in a SOP Geometry dop into a gasParticleToField dop, the "geometry" dop field is created as subdata of the gasParticleToField microsolver. So the path to the geometry field is: /obj/GEO/DOPNET:obj0/Solver/gasparticletofield/Geometry As opposed to attaching a SOP Geometry to the dop object itself, which creates the Geometry field at the object root: /obj/GEO/DOPNET:obj0/Geometry As I said, it's easy enough to manually copy and paste "Solver/gasparticletofield/Geometry" into the gasParticleToField dop, but I want to make this a tool, so I need a procedural way to reference the path to the dop data. I've tried most of the local variables available, but none of them seem to give me that functionality. Essentially, I'm looking for something that will return the path to the dop field when called from a dop node. Example: when called from the gasparticletofield node, it would return "/obj/GEO/DOPNET:obj0/Solver/gasparticletofield/" or ":obj0/Solver/gasparticletofield/" or "Solver/gasparticletofield/". Basically, what happens when you drag a dop field to the textport. Anyone have any advice for relative references for dop fields?
  24. Help with Constraints

    Hey guys, I have two quick questions. I'm trying to learn how to make constraint networks by hand. I've noticed that for some reason, when I define the strength of my constraint in sops using a wrangle sop, I only need relatively low values. However, if I delete strength attribute from my wrangle sop and control the strength in dops using the 'Glue Constraint Relationship" dop, the values needed to achieve the same effect suddenly become massive. For example, when I define the strength in sops, I only need a value of 10 to get the effect I want. However, controlling the strength in dops (no strength attribute defined in sops) require a strength of 100,000 to achieve the same outcome. I'm wondering why there is this massive difference between sops and dops. Also, say I wanted to add a second fracture object to the sim (unique the first one), with a constraint network of its own, whats the best way to go about bringing the second constraint network. From my understanding, adding a new object is as simple as adding a second RBD Packed Object dop, merging that with the original, and plugging the merge into the rbd solver. But with constraints it seems I would need a new constraint network dop and a new glue constraint relationship dop for every set of constraints. I'm just wondering if there a way to do it all through one constraint network dop and use multiple glue constraint relationship dops, similar to plugging multiple RBD objects into one RBD solver. constraints.hipnc
  25. &I66i5iy I ran into this problem where I am exporting multiple pieces of geo from 3ds Max. What's really odd is I could have them act the same as internal Houdini geometry. In my case I have bricks. However, in DOPs, when I go to so fracturing with the Voronoi Fracture Configure Object - all of the bricks just collide without fracturing. If I replace the bricks with anything native to Houdini it fractures as expected. Is there any reason why this is happening? As an FYI - when I imported the geo from Max I had to scale down the scene from 1 to .2. So I don't know if this might be throwing off the mass/density. I would upload the scene but I can't because it's a production shot. I will work on making a proxy scene to upload today if it helps. Thanks!
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