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Found 98 results

  1. /* Accidentally posted in wrong category. Moved to general houdini questions */
  2. 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!
  3. 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
  4. Group in dops [SOLVED]

    Hello ! I'm trying to apply a force in dops to some packed geometry based on some rule. For the test, I use a group that have "@P.y<2.5" in its expression box, and use this group inside of a drag node. But for some reasons, it's not working properly. I never used the group node in dops before, so maybe I'm missing something. Not working properly being the force still applied to the geometry, even though the geometry is clearly above 2.5 in y position. Anyone have an idea ? Thanks ! group_in_dops.hipnc
  5. Link to tutoial -> https://gum.co/imSYS In this comprehensive stand alone tutorial we will go over how to set up scene-scale clustered pyro simulations and blend them together post-simulation to make it appear as if it is one large simulation. This process will lower simulation time, allow for higher resolutions, and be more efficient when saving to disk because there are fewer voxels. This process will also optimize large scale pyro scenes, so that simulations are only calculated where absolutely necessary and blend them together so that it appears as if it is the same volume. This tutorial comes with all digital assets, a documented and fully set up file as well as a starter file for following the tutorials along the same as I work through them. An intermediate tutorial for those looking to speed up their pyro workflow, learn some VEX and create massive sims. Includes a documented scene file and all digital assets! Hope to see everyone leveraging these optimizations in the future to create massive simulations and squeeze in those extra few iterations before deadlines! You can reach me at trzankofx@gmail.com for questions or comments.
  6. Glue Constraint Gravity

    I have been spending some time creating and destroying a building in Houdini but am currently hung up on a constraints problem. In my hip file I have my procedural building, I fracture it, and send the pieces to be constrained together. I haven't meticulously created the constraints yet, I just wanted to get everything in and working first. When I run the rbd sim a ball crashes through the building and blows the middle part of the building away but the top part of the building just sits there floating in the air. Not exactly sure what I'm doing wrong here, if anyone can point me in the right direction I would greatly appreciate it! The hip file has a top level control node to cache everything for you to quickly test skyscraper_destruction.hipnc
  7. Hey guys, I am really stuck with this one. I was told it is impossible to change the scale of a piece inside of DOPS while it's simulating with the bullet solver. I have achieved something similar where the piece goes into dops, gets out of dops, gets transformed in the scale, and then goes back into the same DOPS sim in a loop. So it creates overtime shrinking. But now I need this to happen inside of DOPS. I´m pretty sure it´s possible. Does anyone have a clue.
  8. Hi Guys, I want to scatter some points on a growing and deforming vdb mesh. These points shouldn't jitter on the surface and look like they are moving along with the surface. I have attached a basic file similar to my actual setup. Basically, I am going to render these particles as bubbles on top of the mesh and I want it to be quite dense. I haven't been able to figure this out and couldn't find much help online. It would be great if you guys can check it out and help with a response. Thanks vdb mesh vdbscatter_v01.hipnc
  9. 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
  10. 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
  11. 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
  12. 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.
  13. 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
  14. 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.
  15. 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 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.
  16. 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
  17. Is there a way to calculate the angular velocity from spinning points that only hold "N" "v" and "up", without using the trail SOP?
  18. 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
  19. 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..
  20. 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?
  21. 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!
  22. 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!
  23. 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!
  24. 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.
  25. 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!
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