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Search the Community: Showing results for tags 'constraints'.

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Found 23 results

  1. I have two separate stacks of geo made using copySOP's, i am trying to get them to interact with each other. They do interact with each other but the constrains only effect one model, i can switch them in the merge but its only ever one that holds together, the other falls apart instantly no matter what the glue strength is. Ive put photos below and attached the scene file with the model that needs referencing in. New to Houdini so any help or advise would be greatly appreciated! Thanks PlateSimulationTest001.hipnc plate.obj
  2. I am trying to animate an engine using chops and constraints. I manage to get something quiet close but it isn't accurate(cheat) My main issue is that i cannot find how to use a "look at" in conjunction with some restriction to force the tip of the arm to slide along the Y axis. I tried many other solution as well as trigonometry(which i am not very good at) which i gave up on. i also tried with bones but again my knowledge is close to none in houdini and i wasn't able to restrict bones I wish to achieve the real thing with your help Thank you piston.hip
  3. I have one packed primitive object which consists of several pieces of geo merged together. At sop level (before it is set to become a packed primitive) I have created a core group and an outer group. I would like the core group (the red group) to remained glued only to itself and the outer group(the green group) to be spring constrained to the inner group and itself. The trick is how can I do this without manually blasting the undesired glue connections or using the delete by color method? The reason being that I have very complex geo which is very close together. I have a simple test set up .hip attached. The real which geo I am actually working on it extremely full and chaotic. Thanks! packed_relationship_04.hip
  4. Ok.. so .. How do I setup the wheels of a car that follow a null but retain independent rotation? parenting uses all the transforms types ( SRT)
  5. Hi everyone! I am currently learning F.E.M. (after avoiding it for years ) and I would like to pin few points of a solid object to an animated position. I saw there is a number of methods (using targetP, targetV, ...) but I was unable to make them work.. The Follow Target shelf tool on Solid shelf works weird, it asks only for the constrained object (my solid object), then for the constrained points (I select them on the solid object), but that's all! It doesn't ask for the object to actually follow! For the sake of simplicity - I created this simple test with two animated spheres and I would like the solid object between them to be stretched (the points of the solid object, that intersect with the spheres should be constrained to the animation of the spheres). I deleted all the "non-working" failed constrained nodes to make it clean. Can anyone point me in the right direction? Big thanks for any help! FEM_stretch_test_V01.hipnc
  6. Hey, I spent a while prepping and adding to a model house for a destruction project but I'm having a lot of trouble gluing everything together. I can get the components of the house to glue together no problem (e.g. the windows, the walls, the bricks etc). But what I really want to learn is how to glue each of the fractured components to eachother. What I mean is that my house just falls apart, the bricks dont stay attached to the wall, the glass windows don't stay in their frames the roof shingles dont stay on the roof. I'm really hitting a wall here (no pun intended). Can anyone lend me a hand in figuring out how to approach this? The picture is my destruction model. Each component (roof, walls, etc) has its own constraint network but they arent glued to eachother so when I sim the pieces just pop off.
  7. Hi everyone, I'm brand new to Houdini 15.5 as of October 2016. I have been learning a great deal in a short time but there's some things I would very much like to figure out for something I'm working on. I'd like to know how to create an effect where a membrane, eg a cell wall, is being broken apart when particles collide with it. I know how to do fractures based on particle collisions and I assume it's a similar process. I'm just not sure how to get that tearing effect you might expect when seeing a membrane lose its surface constraint. I appreciate any help from some of you more expert wizards out there. Thanks in advance!
  8. 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.
  9. Hey there, I am currently trying to simulate a (single) falling fir-branch like the ones you can see in this image: I would like to use a wire solver for that, but I am having a hard time to make the needles stick to the branch. How would you go about that? Desired setup: * branch as wire obejct (soft body behavior when colliding) * needles as wire object attached to the branch (soft body behaviour as well) * gravity in place, falling fir-branch, colliding with a ground plane. I tried the "Attach wires to surface" shelftool, but that attaches the selected wire points only to existing points on the branch-geo (which is low res, with just a few points). I would like the needles to be independent of the branch geo so that I can have a rather lowres branch geo (tube, less subdivs), and lots of needles. I would like to attach them like it is possible with folicles in maya, having them stick wherever they are on the surface, not having them stick to one of the input points on the fir branche geo. Using the point attribute "pintoanimation" or "gluetoanimation" also does not work. Doing so, the needles jitter around as soon as they are not in line with a points of the underlying branch geo. Do you guys know any solution for that? Thanks in advance for your time and help! Cheers, Philipp
  10. Hi Houdini people, Is there a way to do constraint for RBD solver for RBD fractured object? I have to do rigid body simulation to interact with cloth, so cone twist/glue/Hard constraint are definitely not the options since they are all work for bullet solver. I am still new to this. Please help. Thanks
  11. Hey guys. I'm trying to figure out a destruction setup for things like fences, wooden frames, plywood walls (that thin stuff thats really easy to put a hole in accidentally) etc. The part I'm stuck on at the moment is how to mimic things that are nailed together. Specifically, how to set it up so that when the fence/frame/whatever is hit by something, it doesn't just break apart, but instead just becomes a slight bit loosened, causing it to wobble a bit and fall over slightly. I realize that explanation probably makes little to no sense, so I've included two reference images. One depicts the effect that would happen for an entire fence, the other is for a single beam. I've got an example scene that uses the Cone Twist Constraint. It it gets me part way there, but is obviously way to static, and just stops suddenly. What I would like would be some subtle wobbling, as well as the beam the rotate down abit (to mimic the photo with the horse). I had the idea of using a Glue constraint with a bit of stretch. Problem is, I have no idea how to get a glue constraint to stretch (or if its even possible) and I couldn't find anything on Google about it either . Is anyone able to point me in the right direction for figuring this out? I'm still struggling to understand constraints so any guidance would be extremely helpful Nailed_Wood.hipnc
  12. I started a thread a few weeks ago about using scattering and Voronoi points to create clusters from multiple objects. That thread is here: Clustering without fracturing? Luckily, that was solved after much confusion. However, now that I have that rendered with a few other stuff thrown in, I got curious about secondary fragmentation using those same clusters. The problem I'm running into is when I'm in DOPs and I add a voronoifractureconfigureobject. When there is collision's, there are no fracturing. But, If I un-cluster the bricks and constraints, the bricks will fracture as expected. I attached a photo and my file to the thread :D. Thanks! building_frag.hiplc
  13. Hi, I'm pretty damn new to Houdini. I'm trying to set up a basic cone constraint network for some voronoi fracturing on a cube. I've managed to get glue constraints working fine, but want to use the cone constraint since it seems useful for flexible breakage/destruction rather than the rather binary on/off nature of glue constraints. I've attached my project file, which just contains a box, fractured and with cone constraints added. I'm not sure why the box goes completely mental from frame 1 – what's going on here? I was hoping the constraints would just hold the box pieces together until some force was exerted upon the constraint network, but it seems like the network is exerting force upon itself and I can't figure out why. Any help massively appreciated! Thanks, S ConeTest_01.hipnc
  14. I am super stuck on trying to create constraints across multiple copied geometry. I attached my file to make more sense of it. If you open the DOP Network you can see that from left to right I have a position constraint>rotation>rotation. However, I'm confused on why the second rotation constraint isn't connecting to the 1st. It acts as if it's just a position constraint with a rotation constraint on it. Hopefully my file explains more. It's kind of a mess because I tried to copy the constraints across instead of making a new line each time. Trying to learn the most basic form of using constraints so any help is much appreciated. constraint.hipnc
  15. Isn't it possible to constrain some arbitrary points of one solid object to the points of another one? The SBD seems to expect a matching set of points between the two objects, which I assume works well when the two object have tets that perfectly touch each other. Is there another way to attach two solids that slightly intersect? thanks
  16. I have one cloth object which I have pre-cut in a certain way. I want to have it stitched when the simulation starts but at a given time I want to gradually break the stitches. What kind of constraint can keep two points of the same cloth object together? sbdpinconstraint pins points in space, which I don't want. clothstitchconstraint is meant to work between two different objects right? It kind of works if I set my object to both constraint and goal object, but then how do I create the associations between specific points? Is there something similar to constraintnetwork where I can explicitly specify the constants between points? thank you
  17. Hello, I encountered problem when I tried to dynamically change groups for cloth constraints. I've tried SBD Pin Constraint to attach cloth to animated geometry. As goal object I used geometry with same topology but animated one. When I am not changing pin group it works fine, but I need to change constraints during simulation. But then it goes funky, it seems as it cannot correctly assign constrained point to goal point. Next thing I tried was to use Cloth Attach Constraint node which works almost fine, but during updating pin group points slide over goal object. Could you check attached file? I am not sure what I am doing wrong. Basically what I want to do is to attach points of cloth to animated geometry and then release it. Is there some other way to achieve that? Thanks, Juraj jt_update_groups.hipnc
  18. Hi, I'm trying to get my head around constraints. I'm trying to create a pin constraint. I have constrained a box to a point that I created using the add node. I created a 'name' attribute for both the box and the point with piece0 as a string. Also on the point I have added another attribute with a 'position' constraint type. In the dop network I have a constraint network with a 'hard constraint relationship' as the input, It works when I use the point from the add node to constrain to, but if i switch it out for a packed primitive it doesn't work. is there a way that I can constrain an object to the position of another object. I'm new to Houdini so i'm not really sure what i'm talking about but hopefully that makes sense Thanks! Josh
  19. Hi, folks. I need to set up a simulation where dynamically-generated arrows fly, then collide with a deforming surface and stay stuck to that surface (shields carried by moving soldiers). Importantly, the arrows should NOT just align along the prim normal on collision; they should protrude at the angle at which they collided. This is a topic that's come up before, but I haven't been able to find a satisfactory answer about it. Some suggestions don't quite hit all the elements I need; some are for older versions of Houdini and so might not be as relevant/accurate (I'm on H14). The approaches I've considered are: 1. Particle-based arrows that stick. It's easy enough to copy arrow geo onto a particle sim, and have the particles stick to the collisions surface. However, then the particles have to start inheriting the orientation of the collision prim as it continues to move. This could be handled two ways: The collision geo is deforming. In this case I'll somehow have to calculate how the collision prim has transformed from the moment of impact to the current time. The collision geo is transforming. In this case I'd use rivets to attach non-deforming stand-in geo to the moving collision objects (which don't change shape). Not ideal, but it might make it easier to work with the orientation values? 2. Particle-based arrows that create geo. Having already grown sick of the mathematical jungle of quaternions, matrices, and dihedrals, I wondered if a better approach might be to make each particle spawn some geo in the colliding object's network instead (presumably using a SOP Solver?) , then die. This would hopefully eliminate the need to continuously update orientation. 3. RBD-based arrows with constraints. Moving away from particles altogether, I wondered about using simple Bullet geo for the arrows, and dynamically creating constraints to pin them to the shields when they impact. An advantage of this method would be that it would allow realistic stick-like collisions and bounces for loose arrows--something particles can't really do. If anyone has any thoughts about which of these methods is most promising, or has any specific advice about how to implement them, I'd be extremely grateful to hear. Thanks in advance!
  20. hi guys, I've been working on a shot of my own where a aircraft crashes on the Ground ( reference - airplane crashing scene from KNOWING) . I am aware of the prefracturing process of vornoi and till now I usually worked on static objects so this one is already animated in maya. I got the plain obj seq in Houdini just figuring out how to shatter while the animation still goes on. Found a very less articles about it . Have a very faint idea that its something related to dynamic constraints! can anyone enlighten me about it or any tutorial link for it? Thanks already!
  21. Hi! I've setup a simple scene with a wrecking ball with a chain hitting a brick wall. I've two constraints network a hard constraint that takes cares of most things and then a glue network that keeps the ball together (it's made up from two pieces). The brick just sits on each other and contains no constraints. Everything seems to work fine from the exception that the hard constraints starts to stretch (ie the chain starts to stretch) when the mass of the ball becomes too high. The only way I found to get around this is to increase the density of the chain to 10 times the ball. But it just doesn't look alright. Is there another constraint I should use instead of the hard constraint or is there a way I can increase the strength of the hard constraint without increasing the mass of the chain? Thanks! / John WreckingBall_Constraints_V01_01.hipnc
  22. Hi guys, I decided it was time for me to learn how to properly use constraint networks and I'm wondering if anyone has any pointers. Specifically, how to get constraints in a constraint network to behave like hinge constraints or some other type of constraint other than simple glue. I am using H13 and would like to be able to make constraint networks for RBD packed objects. Thanks
  23. In the example video/hipfile, I have a piece of candy, which is three rbd objects constrained together. Is there a way to do that in DOPs? I know you can "emit" rbds via some expressions in the creation frame parameter, but that doesn't take care of the constraints. Can we make a debris gun this way? Thanks! rbd_debris_gun.hipnc candy.mov