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Found 92 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. 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
  4. Water drop splash

    I know that houdini 16 have cool water drop splash system and there is few tutorials about this kind of effect but maybe someone was trying to achieve this kind of splash when fluid drop falling down and collide with static object, not with the tank like usually on tutorials? I'm trying for two day create this kind of effect usually adding some forces but it is flat :/
  5. Hello, The effect I'm trying to create is a dragon fire effect, However since I've added new translation to the particle emitter and and container the simulation no longer runs correctly. I believe this is to do with the individual DOP networks yet I'm not sure. Any help would be great since I've been stuck on this issue for some time Thank you Dragon_flames11.hipnc
  6. Hi there, I'm trying to control flip particle count per voxel. The idea is to evaluate particle count per voxel on every step (Gas Particle Count) and then analyze the pcount field.. If pcount > n - delete some of particles (pcount - n) to make n numbers. And if pcount < n - add (n-pcount) particles. Any help is highly appreciated. Thanks,
  7. Particle rotate based in friction

    Hi guys I have a question that is breaking my headoff. I have a simple set up, I have a ground to collide and is scattering points in the surface , based in the distance threshold of an animated geo, I created a group based in an attribute, also have the N and v set up. From this group I'm creating particles to simulate some kind of debri left behind of the falling "rock". The particles when are born they rotate until they hit the ground, but not when are falling or "sliding" in the surface of the ground. I have a POPGraings that give me this nice falling/sliding look. Any idea on how to get the particles rotate based on the friction or contact with the ground surface? Thanks for any idea you can give me
  8. Hi guys I have a question that is breaking my headoff. I have a simple set up, I have a ground to collide and is scattering points in the surface , based in the distance threshold of an animated geo, I created a group based in an attribute, also have the N and v set up. From this group I'm creating particles to simulate some kind of debri left behind of the falling "rock". The particles when are born they rotate until they hit the ground, but not when are falling or "sliding" in the surface of the ground. I have a POPGraings that give me this nice falling/sliding look. Any idea on how to get the particles rotate based on the friction or contact with the ground surface? Thanks for any idea you can give me
  9. Hey. I have a problem with overwriting values from wire object in SOP Solver. If klinear parameter (Linear Spring Constant) is set to 300 in wire object and then I'm writing inside sopsolver in point wrangle @klinear = 300; just for test, then my simulation looks different, less stabile (?). Why is that happening? This is the same value so it should be the same sim. I was trying to put sopsolver before and after the wire solver and there was the same situation.
  10. Hi, (Sorry if this kind of question was asked before) I'd like to set up a flip fluid in a fashion similar to naiad's, where the particle density can be set up separately for the surface and the volume of the fluid. (See attached image as an example) Now, the generation of this is pretty obvious, but I'd like the flip solver to behave as if the in-volume particles had a bigger scale or radius (so I'd need less particles to fill the same space). I tried to adjust the pscale attribute of the inner particles, but that doesn't seem to affect the solver. Any ideas would be appreciated... imre
  11. I'm scratching my head over this issue. My FEM object is slipping through the animated Static Object slowly as it spins. The Static Object is set to "Use Deforming Geometry" and does not act as expected. FEM_slipping_through_StaticObject_slowly.hipnc
  12. Hi, I'm wondering how to go about creating a static shape of a stretched cloth/rubber sheet. Something like this: I've got an overly complicated version working where a set of points are constrained to primitives belonging to another geo but I suspect there is a way define pinned points and everything else is under some stretched force? Maybe initial state or rest geo is just a smaller version of itself? Thanks heaps!
  13. Volume convolution on the GPU using OpenCL. For 27M voxels using 100 iterations, OpenCL is 650 times faster than C++ and 12525 times faster than VEX.
  14. 【i'm not good at english】 there are some attribute on particals in dop, i want to transfer these attribute to other points that particals hit on in geo . How to do this? Please tell me the core node, or give me a exmple. Thanks. 【i'm chinese ,so you can ignore the following content】 怎么让dop里粒子的属性,传递到geo里的模型上?原谅我是新手…… 求主要节点,或者例子
  15. DOP Checkpoints disable simulation

    Hello everyone, so we finally got the full FX license for Houdini and I merrily went about rebuilding a setup that I built in the apprentice version, some FLIP shenanigans. The apprentice version wouldn't simulate when I enabled checkpoints, I thought that was so you can't simulate in apprentice and use the cache in the full version. But now I've got the paid license and the problem persists. I set up the checkpoint file name but no matter what interval or trail length I set, all it ever does is simulate frame 1 and write it to disk, then stop simulating the DOP network, showing me memory cache blue in the playbar and just playing the animation. I'm stumped. Is there anything I'm missing or is it a bug in H16? Any help is appreciated. Thanks in advance Paul
  16. sand disintegration

    Hello, I'm trying to get a logo to dissolve/disintegrate into sand. Like it is made out of sand and something is eating out the outside shell and the sand is pouring out. In the attached file I was first trying to use a geometry and use attribute transfer to set the force of a popforce. as I would like to use in the future a more random/noisy pattern. I'm not exactly sure if my expression is wrong, if my whole set up is wrong. I tried to look around for tutorials or thread but couldn't find any. Any idea, suggestion or links would be greatly appreciated. thanks bil Sand_Desintegration01.hipnc
  17. Impact Glue interaction

    I am struggling to architect what I have in mind and it may be quite simple but... somehow I just don't get how to connect the dots. Attached is a file with a fractured sphere (thin shell) and a small obstacle inside moving fast, I want to break/weaken the glue constraint based on the impact data (may be after a certain force of impact. At the moment the sphere gets moved around by the obstacle, instead the sphere should break on contact with the bullet, but not against the floor. Thanks in advance. PS. All the elements inside the attached scene are using the shelf tools, specially confusing is the ImpactAnalysis. impact_glue_interaction.hip
  18. I want to create a digital asset where I need to simulate pieces of a fractured object falling down to the ground to get a plausible initial "lying-on-the-ground" orientation for further processing. Is it somehow possible to simulate until a certain condition is met (for example all pieces are frozen) and then fetch that state as an object merge or something like that? I am sure this is possible with python, but I'd rather take an approach that relies on the SOP dependency analysis alone if thats possible. Any hints would be very appreciated!
  19. Hi guys, I've hit a bit of a wall in the new version of POPs. I have a deforming mesh (skinned character), which I have scattered points on. What I'm trying to achieve is a set of particles that are essentially locked onto their source point until a certain time or proximity from some sort of gizmo, and then morph to the position of another set of points. I have been able to achieve this in the old version of POPs using a position node, but it's rather slow. However I can't seem to figure out how to achieve the same thing in the DOP version of POPS. Any help would be great appreciated. Thanks
  20. I have replaced the file with just a cube so you guys can still see what is going on. It's very basic. It's just a box with points at the center of each piece telling what is active and what is not active. however when I put this expression: point("/obj/Angel/AC", groupbyvals("/obj/Angel/AC", D_POINT, "name", $OBJNAME), "ACTIVE", 0) in the active value DOP that I got from another dude on a forum on here, that expression doesn't work. Can someone please tell me what I am doing wrong here? This is for a demo reel project so I am on a time crunch..that's why I'm posting this. Thanks so much!! Angel_Destruction_3.hip
  21. Hi Houdini friends, Does anyone know how to use mask field in DOP net? I'm doing a simulation of leaves on the ground reacting to a car passing by. I need to control the wind force to affect only where the car is passing, where other leaves remains more still. Is there any way to mask out the affected area and have the wind force only affect that area and have dynamic change on the mask object? Or if there's other ways to do this? Thank you so much!!!
  22. hello all, is somebody has solved problem like this, when i substepping the simulation into 10 substep on the dopnetwork, then setup the step playback frame into 0.1, then i write the cache with step 0.1, i got error number sequence. i had try with freeware for batching rename, but still didnt get the patern number because every 10 frame, the lenght of the filename was difference. its okay if the range under 100 framets but my frame above 3000 fame, its paintfully if i manualy rename the file. is there anyone ever had solve this case? thanks all.
  23. Spin force for RBD objects

    Hi Houdini friends, Sorry to bother you three times in a day... I'm still having issues with the simulation of leaves on the ground. I can't use POP for simulation because these leaves are in foreground and they'll hit the ground and stay eventually. However it seems wrangle torque or angular velocity on the packed points won't work, these leaves are not spinning around their own origin. Is there any way to fix this? I have the files attached that may better explain. Thanks a lot!!!
  24. Hi houdini friends, Is there a way to deactivate the force when it's not in the mask field? Right now I'm doing a scene where leaves rise when a car pass them. I tried to use the mask field to mask out the area that should be affected when the car come, but as the car goes by those affected leaves seem to be still affected by the wind force, but they should fall down eventually. Does anyone know the solution to this? Thank you so much!!!
  25. Hello everyone, I used to cache multiple alembic using the technique described here : http://nicholaspfeiffer.com/blog/2016/1/16/houdini-tip-of-the-day-render-multiple-alembic-rops-at-one-time (Long story short : rop network > multiple fetch > a merge > click render > caches every fetch. That's cool !). I thought that it would work the same way if I use this technique to render multiple Dop I/O node. For the first time I want to use the take system to cache multiple sim over the night (changing resolution and parameters). So in an obj node I dropped 2 Dop I/O, set their "Render With Take" parameter on each one, then dropped a Rop Network, two "Fetch" nodes and set their path to the dop I/O "render", dropped a merge, and hit "render". The result expected would be to have the different takes cached but instead I had the Main take cached, two times... What do I do wrong ? Thanks for the help, if a scene is needed I will do a simple version of it Have a great day/night !