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Found 82 results

  1. 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!
  2. 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.
  3. 【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
  4. 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
  5. 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
  6. 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
  7. 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!
  8. 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
  9. 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
  10. 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!!!
  11. 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.
  12. 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!!!
  13. 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!!!
  14. 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 !
  15. https://vimeo.com/188376689 Hi guys, I posted this on the SideFx forums but I also wanted to share it here... Basically, after the webinar on particles I felt inspired on creating my own galaxy system. The objective I put my self was to create a space opera style looking galaxy. But the real aim was to create the working forces behind it. Basically a system that can define the sun or suns, the initial speed of the traveling space objects and the gravitational pull forces affecting all of them. Also I added a particle absorb relationship, some big particles will gradually absorb the mass and size of the smaller ones, making themselfs more massive and bigger. I feel there are some quirks to polish but overall the core of the system is already there. Everything is based on real physics, or as close as I could get without making it super heavy. And indeed the results varies dramatically (in a good way) acording to the parameters input on to the forces, basically mass of the sun, of the debris around, distances, and initial speed. It was a fun excersice! maybe I will revisit it one day.
  16. Hello! I'm quite new to Houdini - still trying to grasp some concepts. I need to create falling leaves simulation. I have been trying out different ideas but have some questions: 1. Is it possible to have normal/tangential drag (like in cloth objects) for RBD objects - to have some sort of aerodynamic effect ? I would like to use RBD to simulate a lot of leaves faster as I don't need soft deformations. Cloth sim gives very natural falling motion with normal drag active, but is very very slow for several thousand leaves. 2. I am creating my geometry using simple copy on scattered points and then doing Assemble to create individual leaf names. Partition to group them by name. Then feeding it all to DOP. The question is - what would be the best approach if I want to remove from simulation all the leaves which have reached certain condition - i.e. they have collided with the ground (or some other condition - i.e. leaf velocity is 0 for last N frames (For cloth it would be average velocity of all leaf points)). I need to keep the geometry around and render it, but I would like to remove it from Cloth/RBD simulation to speed things up. How are this kind of problems usually solved? Is it possible to remove objects/pieces from dynamic simulations?
  17. Hi everybody, I'm currently working on an effect in H14. I am attempting to have particles die when they collide with an SDF/VDB object. I have been using the collision detect node with the collision target set to DOP objects pointing to my static object collision node. However, it doesn't look like it works. The same collision detect does work with a SOP poly object. Is the collision detect node working with SDF's/VDB's? Cheers.
  18. Hi everyone I applied a cone twist constrain to an obj, and then when i'm trying my sim I can't play in the right way with the parameters. everything I touch my fracture just "bounce" instrad of breaking. I tried to change also the Physical parameters of the object, why this is not working? Thank you
  19. I am building out a Big Bang collision. I have a very large sphere that I use as the all encompassing universe. This is a static object. It is the Universe Sphere. I then have an RBD that I set the "center" parameter/attribute to the Universe sphere center channel. This sphere serves as the Big Bang, which has been fractured via Vonorni. I use a smaller sphere, whose "center" parameter is also set to the Universe Sphere center channel, as the initiator of the collision. I set the radius up for the Spheres. The Initiator Sphere is key framed with a Uniform Scale of 0 and then the very next frame it is set to 1. The size of this instantaneous expansion sets the velocity. I set the mass of the Initiator Sphere way up and I use a Position node to keep this Sphere for the most part locked down. I set bounce to 0, rotational spin to 0, and friction to 0. Over all, these settings, for the most part, keep the Initiator Sphere locked at the center of the Universe Sphere. However, I am getting a very slight wobble, before the Initiator Sphere settled down into a perfect center in reference to the Universe Sphere. What I am asking is what is the most efficient way to stop the wobble and lock the Initiator Sphere to the center of the Universe Sphere. I have looked at Constraints, however, the universe sphere is a static object, not an RBD, so I am thinking constraints will not work. I am looking for a very uniform collision across all out ward moving vectors, much like a uniform nuclear detonation. Any help would be much appreciated.
  20. what's the difference between substeps on dopnet and min/max substeps on solvers. If the substeps on dopnet is set to 10.The globle parameter @Frame is increased by 0.1 every substep. If the substeps on dopnet is set to 1,the min/max substeps on popsolver are set to 10.@Frame doesn't change during substeps. Why is that?
  21. Hello I need to deactivate a passive collider at some point in my sim, and I can't figure out a simple way to deactivate it. I've tried groups, affectors, 'active value'. It's probably a simple fix, but the only 'hack' that I've found is to use a merge under my static object (merge with a null) and keyframe its activation between 1 and 0 Thanks in advance Bernie
  22. Hi guys I'm doing a cloth simulation and I have some problems with collisions as you see in the image. I used volume sampling for collision and it is too heavy and doesn't make a difference so I used a proxy with surface method. I can't send the hip but this is my settings for cloth solver: Min Substeps: 1 Max CollisionPasses: 2 Can you guess what is the problem? Is it collision subdivision or something else? Thank you in advance
  23. Hi! I'm trying to make a custom vortex force from gasFieldVop in a dopnetwork. I'm nearly successful, but no matter what, i can't change the center of my vortex... I'm getting the P value and substracting from it a constant vector, which should be my vortex's center position (those two values are first set to 0 in Y), then i use this vector in two parts: - one for the tangential force, by a cross product with an (0,1,0) vector - and itself for a "spread" from center force. But no matter what i put in my custom constant center, it seems the vortex always use the center of my volume... I've tried to change the P value with a transform node, but i'm not quite used to it so maybe it have nothing to do with that... Does anyone knows what could be wrong? Thanks a lot if anyone can help!
  24. hey I cant figure out how to resize smoke fields when using clustering via point instancing. When I use the smoke source, it wont take the clusters into account, instead using the bound of all clusters together. But I like to resize the smoke clusters accordingly see attached hipfile SMOKE_CLUSTER_TRACKING.hip
  25. I scatter points on a surface and then bring them into a DOP network to do some dynamics. I would like to create clusters for some of the particles, to get bigger chunks at some parts, rather than individual points. Initially I tried to pack some of them before bringing them into DOP, but it seems that the popsource1 node removes any primitive data, so no packed geo are coming out of it. I am not trying to figure out if I could use spring constraints to force some particle groups to stay together. Has anyone done this before? How would I go about combining POP forces and SBD or RBD spring constraints ? thank you georgios