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Found 123 results

  1. SOP Solver and DOP import help

    Hello all! I have a question concerning SOP Solvers in an Auto DOP Network. Im using SOP Solvers and switches to activate fracture geometry at certain times. I am trying to activate a second RBD object in the scene. Inside my SOP solver how do I specify which object the DOP import node fetches from the network? My_Scene.hipnc
  2. Glue bullet

    Hello good people! Freshly new in Houdini and I am trying to tackle the basics here. I am trying to break apart a box using voronoi fracture (works) and the add a glue constraint relationship in the dop network (I have failed here utterly). I have spent about two days trying out just about everything I can find or think of and to no avail. I am using an attribute wrangle to add a constraint name to the connected pieces. My constraint network however tells me that the required data is not found or is the wrong type. I am using bullet as my rigid body solver and I have hit a complete brick wall - I just can not get it to work. I am attaching the .hip file, and I would be immensely grateful if someone could help me understand what I am doing wrong. It seems so simple yet I am completely stuck with this issue. Glue issue.hip
  3. Duplicate objects in RBD pop net

    DOP net question. I want to start with a set number of boxes and have them move around with POP forces and bounce off each other with RBD. Problem is that I end up with two items for each one I put in. For the POP source I setup Impulse activation to be $F == 2. If I use 1 there, I only get one set of items but they aren't effected by the POPAdvect forces. Feels like a rookie mistaken, but I not sure how to set it up. Any ideas? POP Source: Emission Type is All Geo, Geo Source is First Con text RBD Vector Field.hipnc
  4. Dear Friends, I'm emitting FEM objects into a simulation. Since on a given frame I generate at most one object, I don't need stamping to produce variations, it is enough to animate the initial state. My problem is that these objects share the same rest position, which I would like to vary instead. Is there a way to stamp a variable based on the DOP object currently copying the rest positions to the simulation geometry? In other words is there a function that gives a stable but varying value across objects when a DOP simulation reaches out for rest geometry? Thanks in advance! BMT
  5. Custom attract

    Hi I am trying to create a custom attraction tool using popvops. Its a method I learnt doing a houdini course I would like to improve on it but I have been stuck on it forever. Instead of using a pop attract we are using a popvop to calculate the distance of the particles to a point in space and making them move to this point, if I am using a single point to attract them to its working fine, but what I would like to do is to attract them to multiple points ie a mesh. I have tried using the importpoints but that just makes them go to origin. I would like them to move to the rubber toy. Any advice would be appreciated. I have attached the file and the particle stream I am using to test. Cheers Particles.72.bgeo.sc attraction test.hiplc
  6. Hi, I am doing a smoke sim. The sim is too large and so I can't simulate the entire sim in one go. I had checked the checkpoint option and gave a valid path to save the checkpoints files then simed half of the simulation and had closed houdini. I want to sim the rest of the simulation but where do I put the .sim files that are generated by the checkpoint so that the sim runs from a certain frame and not from frame 1 all over again?
  7. Hello ! Is there a way to visualize the forces in a DOP simulation, much like this, but for wires ? I have a Wind Force (not the pop one), and there is no option to visualize it out of the box. There might be a way to grab the force field information at any location (locations would be a grid of points built specifically for that) and pass it down onto the points to visualize the force on the Normals or smth, but I don't know how to. Something like grabbing the result of all the forces at a location, or only a specific force, either one would be wonderful. Thanks !
  8. Hi, I have an imported geometry which I'd like to use in DOP simulation. Can I simulate a simplified(smoothed) mesh and then transfer simulation results to un-simplified geometry?
  9. Spring Constraint

    Error - Glue constraint references unknown object Would really mean a lot if someone could take a few minutes to look at this file. I was trying to recreate richardlord's spring constraint thingy, but had trouble even beginning to get it to work in the first place. I think there's some changes in constraints from 15-16 (im working in 16). I should have the name attribute matched up to all my constraints and all my objects as the same, but for some reason I get an error with, 'unknown object'. I thought it may have been that the constraint was looking for @rest? Not sure. Very new to creating attributes that get used in dops, I appreciate any insight. springConstraint.hipnc
  10. Source RBD objects

    How is it possible to source in RBD objects (hero) into DOP over time?
  11. Hi everyone Is it possible to store a sparse_matrix data structure across multiple time steps without reforming it at every time step ? I am writing a custom dop solver, so I would like to store it as subdata but I am not quite sure how to do it so any help would be greatly appreciated. I have not really been able to find any examples of this in the documentation ...
  12. DOP in for-each loop

    Hi community! I have a huge destruction scene, where I'm stuck with the ground impact dust. Basically i need to make a smoke sim on every collision with the ground. I have my impact points in place, with birth frame data as well. My guess was to make a for-each loop with a DOP inside of it for every point. It works, but every frame it recalculates the whole sim until the current frame, which is of course is not good. The scene is so huge and scattered, doing this in 1 sim would take an eternity. How can I do this in a correct way? I`m sorry, but i can not post any of the hip file. Thanks for reading this, also a huge thanks if you answer. Cheers. **edit: im on H16.0
  13. Hello there, Is there any way to create Geo dynamically inside a dopnet? Specifically, i would like to have growing tendrils, and simulate those as they are created using popgrains. I created a popwrangle inside my dopnet, and created new points and primitives through vex. Unfortunately, that breaks the pop solver, as its not solving the newly created particles (However, if I put a force after the popsolver it works). I thought maybe that resetting the id to -1 (as used in a similiar way with the bullet solver) would do the trick, but unfortunately not. Is there any way that I can force the popsolver to recognize those newly created particles? Thanks in advance, Bajt createGeoinPop_v01.hiplc
  14. Hi, It seems that generally when animating objects in scene/object level, you are only able to animate variables globally. I have a scene with a spinning propeller, and this spinning propeller needs to rotate around its own axis, while being placed in a certain spot in the scene. How is this achieved? All transforms in the scene are global space, so if you need to rotate the object 30 degrees on the X axis, the Y axis will not follow the local transforms and the propeller will spin sideways in circles. Followup question: I briefly had a teacher from Lost Boys school of VFX and he showed me how to properly load animation data into a dopnet. Unfortunately I was just starting out with Houdini as he showed me, so I did not catch the method. I gathered that this should not be done in sop-level ('Use deforming geometry'), and rather with motion / 'RBD keyframe active' operators in the dopnet -- how do I load in my animation data, so the velocities are correct with proper interpolation? Thank you,
  15. Wire solver - rotational constraint

    Hey guys ! This problem has been bugging me for some time now, so here I am ! So I've got a wire that needs to have one end keep its position and the other end to follow a geometry's animation. I specify the face and/or the point to follow. I have the "keep position" figured out, and half of the other figured. I currently have the "following" end correctly follow the geometry, but only in position. I need the wire to follow the orientation of the face of the moving geometry. I managed to do it following one of Houdini's example scene, but it's not applicable in my case. Or I could not figure out how to apply it to my case, so this test is provided with the scene below. See this for a quick glance at the problem. Thanks ! wire_rot_constraint.hip
  16. I'm trying to use the Point Position dop in a rbd packed object sim. Similarly to what is shown in this video. https://www.youtube.com/watch?v=mDkc2gU31sA but with packed objects. In the tutorial he uses the expression dopoption($DOPNET,$OBJID,"CopyInfo","copynum") in the Point Number field. This doesn't seem work on a packed primitives. I don't think there are values for the CopyInfo or copynum parameter. I have tried using @ptnum as shown in the attached screen. Is there a way to use the Point Position dop with packed primitives? thanks
  17. Points follow points

    Hello everybody! I would like to simulate particles on top of pre-animated / pre-simulated (cached) points. So far I only managed to do the "transfer v attribute inside a sop solver" trick. Unfortunately it does not give me the result I imagine. Instead of inheriting only the velocity I would rather like the points to be attracted by the pre-animated points so they tumble around and follow them the animated ones. Basically I am trying to animate some points and then do a simulation on top of it to give it a more natural feel and to be able to art direct the simulation better. I would greatly appreciate if somebody could give me a hint or a solution on how to do that? Thank you! Here is my current progress (particles inherit v): pop_transfer_vel.hiplc
  18. DOP group exprresion

    I'm working on a setup where a couple of polygon curves simulated and breaking apart using a wiresolver and a sopsolver. I've only one wire object and would like to group the wires in that object that are broken so I can apply a force to them. I'm using a group DOP node and in the Group 0 Expression I've this expression prim("..:wireobject1/Geometry", $OBJ, "broken", 0) == 1 The setup works so far so that when prim 0 "broken" attribute evaluates to 1 all the wires belongs to the group and get the force. So I guess it's the $OBJ I'm using incorrectly. It evaluates to 0 because the wireobject1 is the only object in the DOP network. So how do I access each primitives primnum in DOP? If it's even possible to group primitives belonging to one object like this? Is there another way to create DOP groups? Would like to have something like a Geometry Wrangle with a create setprimgroup expression. Thanks! / John
  19. DOP Wire solver - differents width

    Hi ! First post here, I'm starting Houdini since a few weeks only... I'm wondering how to set different width (for repulsion) for each wire I've created. I've tried to create a random point attribute to drive the width into the wire object but it doesn't seems to work, I feel missing something. Help needed Thanks RANDOM_WIRES_0.1.hip
  20. Hi, I am trying to figure out a way to mix smokecolors in DOPs without the effect of the velocity "Maximum" setting. Its a bit hard to describe so just check out my file. I have two methods of mixing the colors. One is done in DOPs putting Cd in the velcity volume of a source volume and setting it to Maximum. Because it is set to Maximum (because of the lack of another better working mode), colors tend to blend in a (somewhat expected) weird way. so two voxels, one with color (1,1,0) and the other with (0,0,1) then blend together to something that is (1,1,1). And I'm pretty sure blue and yellow smoke do not mix to white smoke ;-) The other one is done using particles which inherit the emitters color and are advected by the smoke. In a postoperation I transfer the color of the particles back into the volume and because it extrapolates it gives a nice colormix that is more of a blend operation and looks correct but its way more processing intensive (especially with highres volumes and lots of particles). So my question is: can the result of the particle workflow be somehow achived in dops without using particles? PS: I did try to do the coloring in a shader and it worked (its not in the file), but I would still need to create particles and I guess there would be a pretty large hit in rendertime sampling those particles in the volume. Cheers, Ronny colored_smoke_v03.hip
  21. Greetings all, I am trying to figure out how to emit dynamic objects like particles. An example would be if I wanted to do a shell casing simulation, or something like in "Cloudy with a Chance of Meatballs" when bead (fem or grain solid object) could be emitted from a plane in the sky. I think this is what they are doing in the bacon example in the grains masterclass, but that file is not provided in the course materials. I have been toying with dops for a bit but I don't even know where to start with this. Would I use a multi solver? Any help would be appreciated. Cheers, B
  22. Wire constrained to two objects

    Hi! Having some problem here with wires eheh. I'm struggling for some time now to achieve something that first seemed so simple, but i'm really lost now! I'm animating an old style phone, with a cable quite rigid, and i just want to constrain one end to the phone (animated) and the other end to the base (fixed). I have it half working, but i can't figure out how to keep the cable semi-rigid... It just "break" were the wire points are constrained. And want the cable to "leave" the base nearly rigid, then deform, and be rigid again when joining the phone... Keeping the base and phone's orientations... (hope it makes sense, sorry for my english) I've search a lot, read and downloaded examples from tokeru wiki, tested all the constraints, but i must be missing something important... It works perfectly with gluetoanimation when one end is contrained and the other is free, but as soon as i try to make the base's end to be also constrained, it doesn't works... Does anyone have some kind of directions? (You can see in the attached video that the base is "breaking" while the other end seems good...) tel_cable.mp4
  23. Hi all! I have alembic file from Maya and something wrong with it. If I rotate it in SOP context with attribute wrangle node or transform node rotation is okay, but if I rotate the same geometry in DOP it fluttering as if pivot is offset. I think it is on the Maya side not Houdini. The question is is it possible to fix it in Houdini? Or only to take back in Maya? I tried in Maya though but I didn't find a way to fix this geometry for proper work in DOP. abc_test.rar
  24. How to Visualize Wind Force DOP?

    I want to be able to visualize a wind force with noise I'm using to make a FEM object with branches sway in a DOP. I tried to append a vector field visualization DOP and a scalar field visualization DOP. I can't get either of them to show up. I'd like to be able to display streamers that represent the wind, so I can adjust the size of the noise settings. Has anyone gotten this to work?
  25. Inside DOP cluster grid source

    Hi Friends, I need your help!! I'm playing with DOP, trying to understand it and feel comfortable working with data.. I come across one issue that I have trouble with.. Is there a way to create cluster grid inside dop? The problem is that I need to timeshift whole range to get initial data for clusters.. Here is the hip file, you can take a look.. I would appreciate some extra feedback about the way I approached with this setup.. I'm I doing something wrong? Thank you!! Regards, M in_dop_clustering_help.hipnc
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