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Found 116 results

  1. 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?
  2. 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
  3. Source RBD objects

    How is it possible to source in RBD objects (hero) into DOP over time?
  4. 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 ...
  5. 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
  6. 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
  7. 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,
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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?
  18. 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
  19. fetchdata DOP

    Hi, I wanted to know if the 'fetchdata' dop can be used to fetch the data from outside the dop. I'm trying to fetch a cached particle simulation into my pyro sim but for some reason it cannot fetch the data outside the pyros DOP. If the particle sim is in the same pyro dop then it fetches the data.
  20. Hey all, I'm super new to Houdini with a background in game development. I was going through tutorials on pluralsight and I'm loving it so far. So I've been expanding on the content and diving into Vex, and I hit a snag trying to run a Solver that changes generated point colours, because I wanted read from and modify persistent data on a separate point outside of the solver network. I simply created details on the point in an Attribute Wrangle in dataHolders and thought it would be easy to read and write to them from an attribute wrangler infectedPoints in the solver. The problem is the vex script in the attribute wrangler can't actually read the details ie: int pointsVaccinatedSoFar = detail("../../../dataHolders/dataHolderPoint","pointsVaccinated",0); int maxPointsToBeVaxxed = detail("../../../dataHolders/dataHolderPoint","maxPointsToBeInitiallyVaccinated",0); printf("points Vaxxed so far: %g\n",pointsVaccinatedSoFar); printf("points Vaxxed so far: %g\n",maxPointsToBeVaxxed); The font node pulls the details properly and prints them. But the printf always yields 0 when maxPointsToBeVaxxed should be 10. I'm guessing I'm breaking some kind of data context/scope protocol in Vex buuut I don't know enough about Houdini yet to really understand what's going on if that's the case. Or I guess I'm not using detail() properly, or both Any help would be appreciated! I'm using Houdini Indie so if you guys can read it I can upload the .hiplc file. Thanks!
  21. Curve Force on Cloth / FEM

    Hiya, How does one get a curve force or other such custom force into a cloth sim? Trying to push some cloth grids along a custom velocity field. I found this setup but it doesnt appear to work in H15 Cheers
  22. Probably a very noob question... but what are the differences and benefits of the two ? They both run a simulation over a SOP network... are they any different in what they can achieve ? Thanks! J
  23. Im trying to connect an apply data to a sop solver (even the documentation page of the sop solver says that one of the most common inputs is the apply data node) but no matter what I always get a "Connection to input 0 is the wrong type". The only solution I found is to go through a multisolver node... which is fine but I wish I could understand what's wrong with connecting an apply data node directly to a sopsolver ?? What I would like to do but returns error (despite documentation): The solution I found: Thanks! J
  24. Bullet and Flips collisions?

    Hi, Can someone please help me confirm is bullet is compatible or not with flip simulations? I set up a simple packed geo as a static object for a flip simulation. The geometry collision is properly calculated as convex hulls… (image1) But as soon as I run the sim this weird shape appears (image2) It is like if the flip sim automatically converts the collision geo into a weird resampled volume. is this true? Would this mean that the flip solver will automatically convert the packed geo into a volume? Feel free to look at my set up… I simplified the scene to run a test. (the hip file is attached at the bottom) bulletandFlip.hiplc I also added this post in SideFx forums as is driving me crazy trying to figure the solution... I have figured a work around transforming my collision geo into volumes and then just using regular static solver but I would like to have a clear answer about what is going on here...
  25. Hi, Can anyone shed some light on how to use the gasBlendDensity microsolver? I haven't seen a working example of it anywhere. Here is an example scene with the fields setup, trying to blend between 2 volumes. gas_diffuse_blend_example.hip Cheers
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