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Found 179 results

  1. Houdini community, Hoping to get some advice with something that has me stumped. I've attached a hip file to demonstrate the situation. I'm attempting to create a controlled shatter on a moving object using the Bullet_Solver sop. I've gotten as far as animating my pieces to be active or inactive so they release from the animated object as required, collide, etc. My big issue is how to make use of constraints here. I want to have glue constraints keeping things sticking together in a more interesting way but I can't seem to get them to do anything. Should the constraints themselves be moving or static? Does that matter? Should I create them a different way? Any help would be appreciated. Thank you. moving_constraints.hip
  2. Hello fellow magicians, I've struggled alot with RBDs in the past. Along the way, while doing various projects I spent countless hours researching and debugging and I realised that most of the information is scattered all around... and this is not ideal. So I thought it would be a good thing to have a "main" post where more experienced artists and TDs could share a bit of their experience and .hip files with the rest of the community. There are many instances where this happens here on odforce, for example the thread on small scale flip fluids or the thread on getting rid of mushrooms in pyro. Since I'm starting this, It's only fair that I share a little .hip file myself. With this exercise I'm creating the tipical situation where the Bullet Solver can't stop the wood shapes from jittering and spinning and the simulation doesn't come to a rest. So I added popwrangles and a popspeedlimit to solve the problem. I'm aware that there might be more optimized ways of doing this, maybe with a POP awaken node? Nonetheless, this is my approach to solving the issue. As a bonus trick, I added a way to awaken the inactive pieces only near the desired collider. Here is a very good article on tips and tricks for bullet simulations in case you wanna have a look: https://80.lv/articles/destruction-simulation-tips-and-tricks/ Cheers, Diogo Ferreira rbds_stop_jitter.hipnc
  3. I'm working with RBDs and I want to apply a popdrag only to my fractures from the rbdmaterialfracture node that are in the concrete_chips group. These groups don't seem to come in by themselves, and after a bit of trying things, I found the POP group node... The way I'm doing it now is: I created a point attribute called concrete_chip that is only 1 if it's in the concrete_chips group from the rbdmaterialfracture node. Then in the dopnet, I am using a POP group with group name to "concrete_chip" and have if(@concrete_chip == 1){ ingroup = 1; } Is this the most efficient way of accessing groups in a dopnet. Seems a bit roundabout, but it works.
  4. Bullet deforming static geometry substeps

    Hello guys. I found strange behavior in bullet. I have medieval wooden cart, full of heavy stones, moving fast from the hill. By default, bullet have 10 substeps, should be good enought. Cart is rigged, and it is deformed, twisted so I need him as deforming static object. If I check cart with timeblend, frame increment 0.1 in SOPs, I can see slight movement of geo, dive to DOPs, bullet stones fall, but my cart, deformed static geo is jumping on full frames. No movement inbetween frames. That causes ofcourse incorect collisions and all kind of bad things. I tested in H18, H18.5 same results. So I never had collision geometry substeps??? Is there some easy fix, how to force bullet recompute deforming static object every given substep? Thanks a lot.
  5. Hi, Is this the way to add a SOP Solver in the new RBD Bullet Solver SOP? I noticed that we have access to a lot of nodes inside it. It says "wire pop forces into here" but not sure how to hook up a SOP Solver. I'd like to set up some custom activation inside this RBD Bullet Solver SOP.
  6. RBD unpack sop lost UVs

    Hello guys, I'm setting up a active rbd pieces using rbdconfigure and rbdpack, after the setup even setting to transfer all attributes the UVs get lost.
  7. Hi all! I recently made a free public post on my Patreon, a bit of a New Year's gift. In my destruction classes & SideFX conference presentations I've mentioned that I often use geometry grouping to define the clustered sections in my RBD sims. However, it takes a bit of work to create the feedback for-each loops to set that up, so I've finally wrapped it up into a helpful HDA. Demo HIP file included as well. (I also included the HDA in the November 2020 'quick tip' post, but this version fixes a bug in the size-based prioritization, so for patrons that have that version I highly recommend downloading this one instead!) https://www.patreon.com/posts/45769153 https://vimeo.com/496659441 Hope you find this useful, and that you enjoy the new year! :-) ~ Keith
  8. Hi, The problem is getting RBD Bullet pieces to floating properly: Icebreaker_fake_Buoyancy_Bullet_SpinningProblem.mp4 IceBreaker_Ship_PopForce_VexMask.mp4 im running into problem simulated flat sheets of ice being buoyant in a volume. I can get them to rise to the surface with PopFloatByVolume and also a fake popForce with vex using the pieces depth to mask the upward force. The problem is getting them to not spin around the packed bullet point per piece, and instead have proper per point of the mesh have force applied as per proper buoyancy would. So they lie flat once they get to the surface of the water volume! Struggling with the PopFloatByVolume spin settings, and PopSpinByVolume doesnt seem to play ball either. Im trying to go down the setPrimIntrinsic route, where i could blend slowly the rotation to be flatter as they get to near the surface, but im not hitting gold yet and would be great to know if theres a better route. any ideas or approaches would be amazingly appreciated. attached the hip file with where im at. IceBreaker_PopFloatVol_CustomVolumeInput_005.hiplc
  9. Not long ago I was tasked with a simulation of bags of hard candy falling and splitting open on the floor, with the candy of various shapes and sizes spilling out. This turned out to be way harder then I thought. There is really no built in way for vellum and bullet dynamics to interact with each other in Houdini. After searching the internet, I did find one tutorial on kind of faking the interaction, but it seemed overly complicated to me. So after a bit of R&D I came up with this setup. Its very simple and fast, and solves both the vellum and bullet sims in one network at the same time: It basically works by importing the RBD geo into the vellum collision solver, and the vellum geo into the bullet solver. The mass of the RBD has to be faked in somewhat, so it interacts with the cloth in a more realistic way, but that's it! See hip for example: vellum_x_bullet.hip
  10. Hello everyone, I'm trying to do a multiple explosion effect on a piece of geometry with a glass material and I have some issues with concave shapes. Since the object needs to be transparent I cannot use any kind of pre-fracturing, otherwise it would show. (picture 1 & 2) So I setup a DOP network with a SOP solver inside to fracture the geometry dynamically. (picture 3) It works fine and the explosions are happening as planned. But since the geometry is concave, a convex collision shape is automatically created around it. (picture 5) And this causes the pieces created from explosions to be pushed outside instantaneously (picture 6). So I've searched for ways to handle concave geometry and this is what I found: Use the "concave" option in the "rbd packed object" node. It works! (picture 7). But it is excruciatingly slow, and this chess piece is part of a larger simulation with other chess pieces with similar issues. So in the end it would be difficult to work with everything being so slow. Decompose the base geometry into convex shapes. With the "convex decomposition" SOP for example. Since it produces several pieces, I can't display the result directly as the object is transparent (same issue as picture 2). And since I fracture the geometry dynamically I don't see how I could replace the simulated geo with some display geo in the end. Maybe I'm missing something here, but I don't know how to replace proxy geometry with display geometry when the proxy geometry is dynamically fractured. The "compound" option in the "rbd packed object" node The description of this option looks promising in the documentation, but it specifies that you need to use a node to generate some data, and that node is deprecated... It is replaced by another option called "Create Convex Hull Per Set Of Connected Primitives". But as far as I understand, your input geometry needs to be made of several "pieces" for this option to be useful. Is there anything I missed here? A method for generating collision shapes that doesn't involve breaking your geometry into several components?
  11. If you look at the attached ColIgnoreA.mp4, you can see the "red" and "green" collisiongroup attributes ignoring one another. Results are as expected. In ColIgnoreB.mp4, with those same collision ignore groups, I glue one red and one green sphere together. The free red sphere now collides with the green sphere, which is not as expected. The best I can tell is that when these pieces are glued together, they somehow combine their collision groups. When I set collisionignore as "red green" it ignores them both. However I still want red to collide with red, so it does not work for me. What's more is that Soft and Hard constraints work as expected, ignoring green sphere collision. Only Glue is strange like this. Is there a way around this? ColIgnoreA.mp4 ColIgnoreB.mp4
  12. Packed rbds and friction

    Hello everyone, I'm doing a simple packed RBD sim, and no matter how much I increase the fritcion parameters the objects never lose any velocity. Is this the expected behaviour? I've attached the .hip file. test.hip
  13. I'm having different results in my simulations using packed rbds connected only to a bullet solver vs when using a POP source to emit the rbd packed object into a popsolver/bulletsolver multisolver. The bulletsolver alone is giving me the expected results... I've seen some tutorials and tips by artists that recommend the multisolver approach, because it allows control of the RBD sim using pop forces and wrangles, and thats why I'm asking this. bullet_solver.mp4 rbd_multisolver.mp4
  14. Shooting a bottle

    Hey houdini people, I am trying to shoot a bottle. My approach was to take the bottle and fracture it use glue to keep it together take a bullet and give it velocity to hit the bottle Bottle breaks correctly I am happy Well, step 4 and 5 are still missing. The bullet does bounce off and then the bottle breaks at the bottom which is kinda weird. Is my approach correct? Any hints what to change/improve? Any pointers to a topic I should look into or a tutorial? Thanks for your input
  15. Questions about the bullet solver

    Hi I used bullet solver in dopnet. As a result, the pieces come out. It doesn't simulate correctly (like pushing each other). Any tips on this? I used 'primitive node' to reduce the size of the pieces before doing the simulation so that there are fewer collisions.
  16. trying to hang a body on a rope

    Hi, I'm trying to hang a body on a rope. For now, I'm doing it using hard constraints. The main shape is fractured by Voronoi fracture and all the pieces are connected with hard constraints. The rope attached to it is just a set of spheres connected with hard constraints. So far, I don't like the results. The rope looks unnatural, way too springy and I don't know how to fix it. My questions are: 1. Can I somehow influence the behavior of hard constraints to eliminate springiness? 2. Maybe I should use a different pipeline altogether?
  17. Hello! Does anyone of you know about good ressources / masterclass / tutorials to get a better knowledge about rbd bullet sims ? I am looking after rigid body interactions with different constraint network, sliders, hinge, etc, not the "destruction/fracture" type. I find the attribute driven constraint network a bit hard to wrap my mind around when going for a bit evolved setups.
  18. Hello, I'm currently struggling really bad with completely unpredictable behaviour of the Bullet Solver and am completely out of ideas with how to debug it further. I'm having a large structure fall into a sinkhole and my current test was just about letting the whole thing drop to the bottom. Now what happens is that certain pieces just get stuck in the air and it seems that no amount of attribut cleaning can fix this. I've had this happen earlier in this project, but also faced it on previous ones very arbitrarily. Currently it's stopping any progress, however, hence this cry for help. This is one of the cache-dailies, without constraints, that demonstrates the issue best: This is a screenshot: (((Ignore the ground, it's a seperate sim and just serves as a backdrop here, not affecting the sim, the whole structure SHOULD just drop straight down))) If I glue the pieces together, the thing just sticks in the air and only the bottom rows fall: I cleared all attributes on the input geo, on the constraints, rebuilt the constraints from scratch, all the same. Has anyone else come across this? I tried on 18.0.460 and the latest 18.0.499, completely clueless. Could this be a bug? It seems so arbitrary. This is the setup in it's simplest form: Same thing happens, the whole thing just gets stuck in the air as soon as the pieces are connected by the constraints. The constraints are setup with the default configurations of the RBD tools, the attributes on those are nothing out of the ordinary. I can't seem to be unable to upload anything but screens here, so I put it here: https://gofile.io/d/g6XdaY Thanks for any help, Martin
  19. hi, I have a question about bullet sim's constraint. As a attached picture, I made a Glue constraint between active packed object and animated static packed object. When siming, I expect the bottom box start animating with constraint, like a parant. However, only the top box and one side of constraint point are moving. You might say to just make parent animation in SOP without bullet sim, but eventually I want to attach more fragment objects with soft constraints on the bottom part. I would appreciate for any helps, thanks!
  20. bullet metal bending by constraints

    hi, I have a question about bullet sim for metal bending. Goal is to able to bend many times by a certain condition. So far , I tried a couple of tests, but never work properly. Outline of my thought and trials are: - hit a box and metal is bent momentaily and stop motion and keep a shape completely . And repeat to hit a box and metal is bent over and over again.... - use Glue and Soft(or hard) constraints to switch each other in SOP-solver by conditions of primitive attributes: impact, force, torque, etc. - probably we should not 'next_constraint_name' attribute in order to repeat switching constraints. - When using impact attribute to trigger switch glue to Soft constraints, fraguments start jiggling. This is because I guess fragments geo struggle with mixed constraints. Some constraints are connected as glue, and others are as Soft. - probably when switching constraint type, I should switch a whole fragments, instead of just a hit collsied pieces, in order to avoid strange jiggle. - If I just need one time bending, it's easy. Just picking one frame to switch a whole constraints to Glue. - maybe example pic has too many colliding boxs. Colliding could be happening every 50frames.. Thus, if anyone gives me a very smart rig, it would be amazing, thanks!
  21. Interactive Wedge

    Hi all, I've explored the various options for wedging, but they all come down to writing results to disk, and I'd like to avoid that if I can as I'd like to run hundreds to thousands of iterations per timestep. The Wedge ROP for example writes multiple versions to disk. Wedge TOP does the same, but in parallel, from a Hython instance each nonetheless. Useful in their own right, but what I'd really like is this. Where I can vary some parameter of my simulation per wedge interactively, without writing anything out. I've got something which "almost" works, like this. But I can't tell whether it's anywhere near success. What ends up happening makes sense I think, but isn't what I want. That dopnet is singular and I suspect the loop tries increment it multiple times per time step which confuses its internal state somehow. I was hoping I could manually step the simulation, such that I could step it relative the current iteration. But I bet there needs to be unique instances of a DOP network per iteration, such that each can carry its own state. But here I'm at a loss. :S It's a bit of an XY problem, what I've really like to do is run a number of frames - say 10 - per iteration, measure the result and use it to determine what to change for the next iteration. To make a PD controller, somewhat like you do for machine learning and genetic algorithms, like this one. Hip file attached if it helps. Any ideas? procedural_wedge.hipnc
  22. hello good day yawll my test is all about a table will get slowly destroy by using sphere as a glue removal constraint help of attribute transfer but its not working my file is here below anyone plse help me out test.hip
  23. hi, I try to learn to dynamically emit packed objects in bullet sim. So far, emission seems to be fine, but the scale of each piece object are wrong. I tried to set RBD packed object > bullet data > geometry representation BOX and convex. Then display geometry and show-guide-geo don't match, too. I have no idea what's required to do dynamic emission properly. I attached example file. If anyone tells what to fix, I appreciate it, thanks. bullet_dynaEMission.hip
  24. RBD And Glue - 17.5

    Still having a lot of trouble understanding the RBD / Constraints system fully. If anyone could help me out with this it'd be great. I've got a sphere set up with some soft constraints and a cube, one is inactive and one is active. I just want to be able to glue the sphere to the animated cube while still respecting the constraints all ready applied to the sphere. Nothing I'm trying seems to work. I've attached a quick scene file, if anyone could point me in the right direction with this it'd be hugely appreciated. RBD-Glue.hip
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