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Found 187 results

  1. I'm working on a POP simulation for a rainy window and I've set up the simulation so that source particles (in yellow) fall with erratic motion due to a varying POP Wind force and Gravity force, emitting a stream of particles behind them (in green) as they fall using POP replicate. The emitted particles are stopped immediately after emission (using the stopped attribute in a POP wrangle). The issue is that as soon as the POP replicate is activated (at frame 200 in the video), the erratic motion of the source particles is lost and they travel more slowly in straight diagonal lines (as the trails of the emitted particles show). I believe that the POP interact node is causing this as the source particles are being attracted to the stationary emitted particles, slowing them down. But what I don't understand is that the POP interact and replicate are in separate particle streams so the emitted particles shouldn't have any effect on the source particles. I've attached a hip file along with a video illustrating the change in motion when POP Replicate is activated. Any help would be much appreciated as I'm pretty stuck on this! Thanks Houdini_POP_Replicate_Question.mp4 POP Replicate Issue.hip
  2. Dop import not working

    Helllo, I am new to houdini and trying to experiment with rbd but I fail to use the dop import node properly. I am trying to fetch the geometry of the dopnet inside an sopsolver. What am I doing wrong ? Thanks in advance.
  3. Hi all. This should be easy, but it's killing me... I have a control object living outside a DOP network, a simple particle system. I've plugged it into the second input. Inside the DOP I access this control position without issue, in a VOP. However I then want to follow up by killing particles in a POP wrangle, based on distance to the control object... Easy right? Here's my vex: f@dist = distance(@P, v@opinput0_P); if ( @dist <= ch("threshold")) { removepoint(0,@ptnum);} ... simple. But it kills particles around the origin, not the control object, as if v@opinput0_P = {0,0,0} I've tried multiple variants on opinput, explicit path and the point function etc but it always gives me a "kill" radius around the origin, not the control object. Anyone see what I'm missing? Thanks in advance!
  4. Hello! This is my first time posting here. I am a graduate student currently working on a project that involves a character comprised of rigid objects that can assemble, disassemble, and rearrange itself. The parts can also blend between dynamic and keyframed states. I have a method for the state switching, but I cannot seem to find away to apply any attractive or guiding forces to the parts when they are in their dynamic state. I found a way to do this previously by using a POP Attract node, but it only worked with Rigid Body Solver. I'm not sure how to apply that same node to a RBD Solver. If any knows how to make that work or knows a better method, I'd appreciate it. The goal in this test is to make the ball roll towards the cube and fit into one of the sockets. I have attached a zip file with the assets and .hip file. Thanks in advanced! RBDTesting.zip
  5. I`m currently working on high resolution of flip simulation but sometimes it`s crashing middle of the simulation and i think it`s memory problem(I`m doing something else while simulation) And i realize that .sim file is can save the simulation progress and i can start up with .sim file to resume the simulation. But during simulation saving whore simulation to save .sim is very waste of disk, saving time,, extra So what i want is after the simulation is done or houdini is crashed or user stopped the simulation, i want to save last of 1~2 frame to resume the simulation! Is there any way to do this?
  6. Hi guys, I'm looking for some tutorial that helps me to understand DATA in the DOP network a bit more, in-depth. I mean something that helps me to work efficiently with dynamic nodes like: "Empty DATA", "Apply DATA", "Copy DATA", "Fetch DATA", "Modify DATA", and so on... Why they use this: " /obj/AutoDopNetwork : flipfluidobject / collision "? Is the "collision" one of the data and this is another way to grab it? Where can I find a list of several DOP DATA? I took a look at HDK on this page: https://www.sidefx.com/docs/hdk/_h_d_k__data_flow__d_o_p.html But I find it too complicated Thanks for helping.
  7. Deforming texture maps in Dops

    Would the deformation of texture maps work DOP networks?
  8. OK I read the section , Thank you for informing us about broken group and sop solver DOP , but how can we do that? I need to know about workflow.
  9. Hi there, I'm trying to understand Dopnet a bit more in depth and try to understand a bit better how you can transfer data from one object and use it in another. While playing a bit around I ran into a problem where I don't understand why this isn't working. I created a simple particle setup, and after a hit of a particle, a sphere is created into another object (called 'col_gen'). What I try to do is using these spheres in the next frame as a collision for the particles again. But somehow I can't get it get to work. Simple as that, right? What I did try is using the path "../:col_gen/Geometry" in the soppath of the static object. That doesn't do anything. So I tried to reference the geometry into an sopGeo node, and apply that data onto the staticobject. But that doesn't work neither. Question 1 is: Why doesn't this work like this? And question 2 is: How would you solve this problem? Cheers, Sander (The hipfile is hidden underneath the screengrab) generateCollision.hip
  10. Hello everyone ! In order to model a ceiling mobile (such as the ones in a baby's bedroom), I dived in the depth of wire objects, and I feel like it is much less intuitive than the usual DOP workflow. What I want to do is to tie certain objects (in my case, that would be origami birds modelled with the help of the amazing entagma tutorial from last week) to wires, which are tied to a static wooden part. The part where I'm having issues is when it comes to tying together the solid objects (which come as a RBD packed object) to the wires. I've tried several methods, all of which have failed me for now. 1. I tried using the SBD pin constraint from the Wire shelf. It kind of works, but I still find it very hard to control, and it is impossible to simulate the physical behaviour of the whole system (I have to simulate the RBD packed objects separately, and tie the wires afterwards). 2. I tried the more classical RBD approach, using constraint networks. This is the approach I would prefer, since it allows me to simulate the full system. I have set up the constraints using a Connect Adjacent Pieces SOP, which I modified a bit to add the anchor_id attribute on the constraint points. All of my pieces, whether it be the RBD packed object or the wires, come as separate objects with their own unique names matching the name specified in the constraint points. However, when I play the simulation, the constraints do not tie the objects to the wires, and the wires go wild while the RBD packed objects fall due to gravity. 3. I've started looking at Vellum and other cloth simulations, but I'm very new to it and it doesn't seem to integrate very well to RBD workflow which I'm used to. I've attached a hda with my project file, where I've replaced the bird objects with polygon spheres for simplicity. (It still doesn't work when I play it on my computer) If anyone has the time to take a look at it and tell me what I'm doing wrong or put me on another track, I'd be super grateful ! All the best, Nolan Constraint_Wires.hdanc
  11. Sparse pyro distributed simulation

    Hi, I was wondering if there is a way to distributed sparse pyro simulation. You can easily distribute with legacy pyro by distributing the container by slicing. I mean yeah... there is a predefined container that gets sliced in legacy but sparse create bounds on demand that is why it can't distribute in sparse since there is no predefined container(bounds). But has someone cracked this...? Simulation sparse on multiple machines
  12. bring data from a dopnetwork to another

    I have a pile of sand simulated with grain. I want to use the initial state for the sand and afterward use rbd to interact with the sand but the problem is, when I use the initial state nothing work inside the dopnetwork anymore. I think there a way to bring the grain data to another dopnetwork or I must do something else?
  13. duplicated object as a fracture

    how can I convert a duplicated object a separated objects to work as fracture object inside DOP NETWORK? Duplicated_Objects_as_Fractured.hip
  14. object vs data in DOP network

    are there any good resources to explain these two subject? object - data what are they exactly and what they do inside DOP network? any pages of documentation or any piece of information you give me is acceptable
  15. Hi. I am trying to make a simple HDA which will drop down an asset on another asset. It works fine inside Houdini but it doesn't work in UE4 or Max. What is wrong with current setup? drop_dop.hda
  16. Volumesampleindex returning 0

    Hi, I'm currently trying to implement a smoke volume that wraps around the X-axis. Essentially taking the values of the final voxels on the +X axis and applying them to -X. The VEX below should be doing what I want, but its returning zero every time. Am I missing something? I've tried deriving the voxel coordinate procedurally, as well as manually specifying a good known coordinate, and every time I get an empty result. Its driving me mad! float scratchpad = chf('scratchpad'); int far_voxel = floor(ch('../smokeobject1/sizex') / ch('../smokeobject1/divsize')); vector sample_pos = volumeindextopos(0, "density", set(far_voxel, @iy, @iz)); if(@ix == 0){ //f@density = 1.0; //f@density = volumeindex(0, "density", set(far_voxel, i@iy, i@iz)); //v@vel = volumeindex(0, "vel", set(far_voxel, i@iy, i@iz)); f@density = volumesample(0, "density", sample_pos); v@vel = volumesamplev(0, "vel", sample_pos); } The commented out lines are different methods I've tried with no success. So far I've tried using volumeindex to read the voxel values directly, and volumesample using a position derived from volumeindextopos. No dice Any ideas folks? (the attached image shows the current behavior using the wrangle VEX above. What should be happening is the density and velocity values on +X boundary should be being copied into the -X boundary voxels)
  17. I found that volunteers are making a Houdini18 version of GasUpRes. Sparse Pyro Upres, the easy way - part1 (Vimeo) Sparse Pyro Upres solver for H18+ [hipfile] (Vimeo) So, is it possible to make GasUpRes with minimal solve in Houdini 18.5 version as well as these? Thanks!
  18. POP wrangle number of inputs

    Is there any way to add more input slots in a POP Wrangle node? By default it has 4.
  19. Hi there, I'm trying to learn vex, but I've run into a bit of trouble with the RBD solver. My goal is to apply forces to individual points on a model, and have the model respond appropriately. My first assumption is that I would use a bulletRBD solver to accomplish this, along with a POPForce node. However, this applies force to the center of mass of the object, which is fine, but I also want some rotational values as well. For instance, if I have a cube, and I apply force (0, 10, 0) to verts on the left side of the cube, and I apply the opposite force (0, -10, 0) to verts on the right side of the cube, I would like to see the cube spin. I know I can manually edit the @w attribute to add angular velocity, but do I have to calculate the angular velocity manually to make this work? Thanks for your help.
  20. Hello, I am following a tutorial on DOP Networks and Rigid bodies but when I apply a quickshade outside of the dop network and try to Import it as an RBD Object, it doesn't bring in the texture. I am not sure what is wrong? Can you please help? Please find attached the scene file. Thanks. TextureProblem.hipnc
  21. Hi; I'm looking for some training on how to work with DOP Data. I mean several ways to fetching and applying DOP data, to control velocity, temperature, and so on... Thanks for helping.
  22. POP Sourcing into specific DOP object

    Hello, I have two different DOP Objects (RBD Packed) and I want to source Geometry into just one of the objects, not both. I am using the popsource node which by default sources to both of my objects. (Using just one object is not an option for now) Any tips? Thanks!
  23. Having a problem with a Motor in a Cone Twist Relationship for a few days. It's stop working after 50 frames (not generating any torque) if I animate a motor values. Parameters animated like 0 to 30 to 0 to 45 to 0 to -45 to 0 etc.., so motor should only increment a small angle per timestep. Tried to modify almost any parameter I could from lowest to highest, no success (apart from Time Scale, but it's not really a solution). Simulation substeps don't have visible effect either. Minimal working setup in the attached file. Banging my head against this problem for a couple days CT_problem_apprentice.hipnc
  24. A small fluid-related question

    Hi, Currently, I'm working on a small sim where a character gradually fills up with water. I'm trying to have more control over the emission rate, when using the emit particle fluid shelf tool. It seems like the "Scale Source Volume" slider on the Volume Source DOP has been removed. Normally, it would be found below the "Activation" slider. I attached a screenshot of the parameter view of said node. So, my question is as follows: where can I find a similar parameter in Houdini 18? Best regards
  25. Hi, Is there a way to do @disableexternal on each object individually ? I would like to disable it for one object but not the other. Thanks !
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