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Found 577 results

  1. Hi guys, I hope you can help me with setting up this vellum inflation scene... Basically, I have animated a sphere expanding and used the rest blend node inside the vellum solver to inflate the sphere. What I would like to achieve is an interaction where the vellum inflation sim interacts with a rigid body 'plinth' that it is initially sitting on rather than it just being a static collider object. I have tried using the vellum shape match constraint for this behaviour but have found it tends to deform the shape which is not ideal. Preferably, I would like to know if it is possible to use RBD dynamics inside of a DOP network and have that interact with the inflating vellum sim... The entire sim would also sit inside of a static container too as the plan is to squash the vellum soft body against the walls of the container. Any help on this would be really appreciated. Thanks! Vellum_Rigid_Body_Interaction.hiplc
  2. Hi guys, I have two RBD objects, floating on FLIP-fluid. I set the Density (mass) to 400 (lower than the fluid mass). When two objects are of the same amount of mass, they have to react in the same way, right? I mean in this case, they have to stay on the surface. The problem is the bigger object stays on the surface, but the smaller one sinks into the fluid: - How can I fix it? - How can I set the density(mass) in the SOP level (as an RBD source)? Thanks for helping. Floating RBDs.hip
  3. Bacterial Growth with Bullet

    Trying to do bacterial growth with bullet, I can grow the bacteria rods with the v@scale attrib and then replace the extended rods with two split bacteria, that then grow and split: replicate_bac_8-31.mp4 The problem is that the rods don't get pushed around like I would like. They wind up all oriented the same and pile up on each other. I am sure it is due to how I am sourcing the split prims... When I simply spawn the rods and then grow them they push each other around properly: spawn_bac_8-31.mp4 Here is the hip file with both the grow and split and the spawn: bac_replicate_rnd_01.hiplc There's an old post on this topic that has a good reference for the bacterial replication, but no attempts at using bullet: I also tried going back to 18.5 and using intrinsic transforms instead of what I suppose is the naive method of copying to points, - and using the reset bullet id trick instead of the @scale attrib as in H9.X - but the results were pretty much the same, here's the hip for that: bac_rnd_18-5_01.hiplc And also some other nice ref showing how the bacteria can twist and make strands ( ultimately the goal is to show a similar effect): elife-32976-video3.mp4 I would appreciate any insight into this - a lot of this bullet stuff still seems like voodoo. For instance I am merging the new prims with existing prims and then deleting the old prims just to get the bullet attribs on them, I couldn't find any information about how to properly initialize new bullet prims for example. So thanks for any attention to this -jb
  4. Hi all, I am hoping someone can help me understand why my geometry looks like this after fracturing, it has some weird anti-aliasing(?) geo issues on the glass texture after using material fracture. Have an image here of before fracture and then after fracture. If anyone can help me understand why this is happening, would be really grateful as i've bee unable to solve this for hours. thanks Before fracture After fracture
  5. Houdini rebar

    Hi I'm working on rebar, How can I make the rebar directions follow each other like in the video? -> https://vimeo.com/251055761
  6. Hello. I watched this tutorial video and created a spring simulation. Next to that I want to give Collision to the spring constraints so that they collide with other objects. Do you know of any way to do this?
  7. Destruction II - SOP Level RBD

    Hello Houdini Artists! I'm proud to say that my latest course - Destruction II is now complete. This course has over 6 hours of tips, tricks, and techniques for improving your RBD simulations. Check it out at cgforge.com if you're interested Cheers everyone!
  8. hard constraint with condir and dof

    (Apologize in advanced if this post bothers you, cause i've posted on sidefx forum, but no luck from that.) What is up everyone, I've been working on rbd, and I have a question about hard constraint working with condir and condof. I've set the constraint type to "position"(means i want to constrain the position of the object) condof to "1"(means free to move on a plane) condir to (0, 1, 0)(means the normal of the plane) so theoretically the object shouldn't move up and down since i've constrained the movement of position of the object on "X-Z plane", but why does the object still move up and down after i set the initial velocity to (0, 1, 0)(also there is a gravity node) It confused me a lot, please help me with this problem, if i misinterpret anything(concepts) or did something wrong, please let me know, because with more time considering and trying with the problem, i found that maybe i have wrong concepts in my mind.(Maybe the degree of freedom concept, and i found that rotational and positional constraint might have to work together in order to get the positional constraint function correctly, not sure about that) Thank you, really appreciate your help. constraint.hipnc
  9. Hey guys i tought that the pop collision detect sop would work in both pop solder and rigid bodies solver. i want that the rbd pieces sticky/stop when collide in a geomtry. however i have no ideia how to build that in rigid bodies. please help me stop_at_collision.hip
  10. Hello, Trying to work with RBD bullet solver and conetwistconstraint, but I found a limitation in SOP Bullet solver, cause it has only one conetwistconstraint settings, and in case if I have more than one conetwist constraint it become a problem. I tried to add it inside solver but have no success.
  11. Houdini.School | Attributes

    New Houdini class on Attributes. Enroll now: https://bit.ly/houdiniattributesclass Teaser: https://vimeo.com/714350608 Attributes are the heart and soul of Houdini. So many beginners and even intermediate users stumble over the importance of knowing the in and outs of Attributes. Understanding this topic is vital to getting the most out of Houdini itself. My goal is to give you a much deeper understanding of Attributes, so I have broken down this class into smaller topics. This way I can take you step by step from the core geometry component foundations, to common workflows, as well as reading & writing attributes from scratch. I'll also take you through examples of actual attribute implementations relating to RBD, FLIP, VELLUM, Crowd sim, and show some Viewport GL attributes. In session 1 you will be shown the core geometry components and how they relate to attributes. You'll also be given some clarity on confusing terminology, plus learn what attribute classes, and types you have available. Also covered will be a full explanation of the Geometry Spreadsheet, plus some tips on how you can sort through all of the data that it presents. I'll run you through what intrinisics are, how they can be accessed, and also explain what attributes are NOT, which is just as important as knowing what they are. In session 2 I will teach you the many different ways that attributes can be created, plus the the ways you can read those attributes back into your node streams. I will also take you through the world of Attributes versus variables, global versus local, and explain the reasoning and history of dollar sign versus the at symbol. In session 3, I'll focus solely on attribute usage in a variety of simulation setups. Showing you some implementation methods for simulation attributes. Houdini comes packed with a lot of native attributes already built in. I've gone ahead and collected together a massive list of well over 8,000 of them for you in PDF form. This course is aimed at getting beginners up and running with Attributes, but I will be taking you into intermediate territory fairly quickly as it's required to get a full understanding of Attributes. There WILL be discussions of VOPs, VEX, HScript, and Python in the second session. Don't worry though, because I will also be showing you many of the native SOP attribute nodes which simplify many common tasks for non-coders. I've packed a lot of information into this class, so even if you are an intermediate user to begin with, there is still plenty of good info for you as well. For more info and to enroll, head over to Houdini.School today.
  12. Hi guys, I know how to use pre-fractured objects in an RBD simulation, but is there any workflow for Dynamic Fracturing? Thanks for helping.
  13. Hi, I created a rbd simulation with a heghtfield to create a more interesting collision rather than a simple flat plane. The issue that I have been noticing is an offset from the actual collision when I am dropping a ball. The collision guide seems fine as it follows the geometry so I can't really understand why is this happening. Hope that someone can help. PS: I have attached the file below Cheers TEST_RBD.hipnc
  14. Hi. I have a setup with boxes scattered in a circle position. Inside rbdbulletsolver i try to use LookAt in order to force boxes always face the center while they move around. But fo some reason look at rotates all boxes. I know there must ne something with up vector but cant fiure out by myself. I tried to different options within look at and tried to assign different up values but still cant figure out how to make look at force objects to actually look in the center of coordinates without weird rotation. Please... help The file is attached. untitled.hip
  15. How can we control the shape of a chramp (created in a point wrangle) with a spectrum chop and therefore animate the shape? I already posted a question related to this, but maybe it was worded confusingly or seemed difficult..as no one answered. So I am asking generally, alternative solutions are welcome.
  16. I wanted to ask for advice on combining two setups. One is using spectrum chop to displace the points of a line along P.y independently. The other one is a RBD bullet sim. A POP Wind is moving the fractured pieces of a box away from their original position. Using a time shift the sim's progression can be offset along the z axis and the offset is controlled by a chramp. Now I want the data from the the spectrum sop to instead of displace the points along P.y fit the amplitude from 0 to 1 and remap (?) it to the frame range of the pre-calculated sim, currently frame 1 to 50. I sorted the the simulation points along the z axis and would like to use the audio spectrum to drive their time offset, instead of the P.y. Need to figure out the maximum amplitude of the spectrum chop and fit it to the last frame of the sim? Attached is the .hip containing both setups and an audio file (royalty free track used by the tutorial creator of: Houdini CHOP Talk 3 Audio Processing 1 - Audio Spectrum https://www.youtube.com/watch?v=J754SLvE7BQ) The audio doesn't matter, I just wanted to provide anything.Downfall.wav The line's points are evenly spaced, but the bullet sim points obviously aren't, so I would like that to remain unchanged.. retimed_sim_1.mp4 retime_sim_with_chops.hiplc Downfall.wav
  17. RBD fractured objects issue!

    Hello, In an RBD simulation, I would like to control the transform/rotation of the elements, to stop them from moving forever. The fractures travel too far away..! I tried to use the "Drag" node, but it's hard to achieve the right value in its parameters! So what's the best solution to fix it? Actually, I want to achieve a falling behavior like what they made in this TVC: Thanks for helping. RBD Limiting Drag_02.hip
  18. Hi ! I'm currently struggling on breaking constraints. I want my constraints to break if their length is higher than a given threshold. These constraints has to be soft constraints and I have to keep them animated (it's for my work). I tried to break them in the SOP Solver connected to the constraintNetwork, but for a reason it doesn't work at all. I've created hip file to show the problem more clearly. If you dive into the SOP Solver node you'll see that, long constraints get detected, but it doesn't affect the simulation. Break_Animated_Cst.hipnc
  19. Optimized RBD Sim

    Hey guys ! I'm currently doing a RBD project and I was wondering if you guys had any tips on how I can make my sim more optimised so that it doesn't take 25 min for only 10 inactive frames. The fracture is pretty low res and all the substeps settings are low but the sim is still really slow and practically unworkable. I have 100K pieces correctly named and the building is world scale so i dont know what to do to make it workable, any tips? I would greatly appreciate ! Thank you
  20. Hi, I'm trying to remove objects and collision objects from an RBD Bullet Solver simulation. Removing objects work inside the node connecting a geometry wrangle to the presolve output using 'removepoint' with the packed rbd geometry. I try to do the same with the collisions, but I'm not sure how to access the collisions from the geometry wrangle. I also tried the Collision Geometry input of the RBD Bullet Solver, and use a switch or move the geometry of colliders, but it does no seem to work. Any suggestions would be appreciated. Gabor
  21. Hi guys, i am looking for a solution, that same bricks are fighting on some area because they cant reach their target pos or their target rotation. They try to reach the target pos and rotation but they are preventing each other. Are there any Ideas on how i could fix this without loosing collision?
  22. Hello there, In a Packed-RBD glued simulation, how can I pin the base of a series of glued objects to a fixed position like a wall? I also need to control the angular stiffness... I tried the "Bullet Soft Constraint Relationship", but no success! Thanks for helping. PackedRBD_Glue_Pinned_02.hip
  23. Inner glass faces not deleting

    Hi, I made a rbd simulation of a glass building and I am trying to remove the inner faces as they show up in the render before any force gets applied to the building. The issue is that when I am applying the dop import after the rbd connected faces, the prim distance doesn't change for each inner face and therefore the faces at frame 1 don't get deleted. I created a simple file with a fractured cube with both a rbd bullet solver (which works) and a dop import connecting a dop net containing a rigid body solver (which doesn't work). I am sure that the dop import settings is the node that has the issue but I am unsure how to solve it. If someone knows how to make the distanceprim attribute work pls help. test19.mov test_int_faces.hipnc
  24. Is it possible to access primintrinsics in dops? I have Geometry wich is transformed by a sim. For the second rbd sim i want to make the geometry look at a particular direction. For example to its original direction. So I deleted all Attributes from the first sim to prevent side effects and connected it in to the second sim. To make it look to a direction i want to use the poplookat node (target is direction) in dops. I enabled VEXpression. This is my VEXpression setup: target = {1,0,0}; refdir = v@xdir; up = {0,1,0}; refup = v@ydir; Now i need the original X direction and the Y direction from my Geo. I could convert the primintrinsic "transform" matrix to the directions, but somehow it is not possible to do that in dops. is there any solution?
  25. Hey, I was wondering how I can have the hero object inherit multiple incomming objects but treat them as seperate items. I can import one item, replicate it in dops and adjust each one with $OBJID but cannot import multiple layed out objects without having them act as one entity. hero.hiplc