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Found 136 results

  1. Help with Constraints

    Hey guys, I have two quick questions. I'm trying to learn how to make constraint networks by hand. I've noticed that for some reason, when I define the strength of my constraint in sops using a wrangle sop, I only need relatively low values. However, if I delete strength attribute from my wrangle sop and control the strength in dops using the 'Glue Constraint Relationship" dop, the values needed to achieve the same effect suddenly become massive. For example, when I define the strength in sops, I only need a value of 10 to get the effect I want. However, controlling the strength in dops (no strength attribute defined in sops) require a strength of 100,000 to achieve the same outcome. I'm wondering why there is this massive difference between sops and dops. Also, say I wanted to add a second fracture object to the sim (unique the first one), with a constraint network of its own, whats the best way to go about bringing the second constraint network. From my understanding, adding a new object is as simple as adding a second RBD Packed Object dop, merging that with the original, and plugging the merge into the rbd solver. But with constraints it seems I would need a new constraint network dop and a new glue constraint relationship dop for every set of constraints. I'm just wondering if there a way to do it all through one constraint network dop and use multiple glue constraint relationship dops, similar to plugging multiple RBD objects into one RBD solver. constraints.hipnc
  2. &I66i5iy I ran into this problem where I am exporting multiple pieces of geo from 3ds Max. What's really odd is I could have them act the same as internal Houdini geometry. In my case I have bricks. However, in DOPs, when I go to so fracturing with the Voronoi Fracture Configure Object - all of the bricks just collide without fracturing. If I replace the bricks with anything native to Houdini it fractures as expected. Is there any reason why this is happening? As an FYI - when I imported the geo from Max I had to scale down the scene from 1 to .2. So I don't know if this might be throwing off the mass/density. I would upload the scene but I can't because it's a production shot. I will work on making a proxy scene to upload today if it helps. Thanks!
  3. Hello! I'd like to share with you an interview with two FX artists from Naughty Dog who worked on Uncharted 4: A Thief's End. In it, Neilan Naicker and Ray Popka talk about using Houdini for doing destruction, rigid body fracturing, ingame dynamic rivers/flowmap generation and spawning thousands of running chickens! See full interview here: http://www.sidefx.com/stories/fx-adventures-in-uncharted-4-a-thiefs-end/
  4. Hi all, Am trying to tweak a scene file that was passed to me from here (apologies, I don't know/can't find original poster, so can't credit). It's a wire sim where points are activated based on their Y position - And I'm trying to tweak it to be based on color. I've worked a nice way to animate my colour across the points in a way I like, but my question is: How do i get my point color attrib to update per frame in the dopnet? And how do i associate it to the gluetoanimation value? Been really trying to get this going today, but to no avail... Any help or tips gratefully received! activate_sim_based_on_color.hip
  5. Random Merge node Output

    I'm trying to figure out a way to take 2 objects in a merge and then randomly output 1 or the other to a CopySop. Simply, I have the copy connected to particles and I just want the shapes to randomly go to a random particle. Right now(for obvious reasons) it's just taking the 2 merged objects and assigning both of them to each point. I attached my file and left a blue sticky under the green nodes where the issue is taking place. I do have questions regarding this problem. - I know I can merge multiple objects and then in the DOP node that has those particles, just use packed geometry to achieve this. - Is it even possibly to do what I'm trying to acheive in the way I'm trying to in my example file? - Which method is best? - if one is better than the other? Many thanks in advance! I'm always unsure if I'm being super confusing, so I apologize if I am. dop_crack_part.hipnc
  6. POPS Geo wrapping from DOPS?

    I'm new to Houdini but I know that when version 13 came out, POPS AND DOPS were merged into Dynamics. For the life of me, I can't figure out how to make particles into geo shapes. I'm not trying to create POP Particles that are then converted into proper rigid bodies. I'm literally just trying to take the POP Particles and add a shape to them. So yes, there will be intersections between the particle shape and collision geo. I attached my file. I could get the particle to be wrapped/meshed as spheres if I did use a copy sop on both a sphere and a POP setup. But trying to have those particles collide with other geo wasn't working. If I'm being confusing - in the most basic form, I just want the colliding particles to be meshed as a sphere. Those spheres don't need to be collision accurate, they just need to wrap the particles. Thank you so much for any help! Best, Michael POP_SHAPES.hipnc
  7. inflatable wind sock

    Hi everyone. I'm looking down the barrel at a very cool project that involves creating a CG wind sock and blowing it around in the air. After poking around in Dops for a while I decided it would be a good idea to involve the expert Houdini community. Essentially I need to create a wind sock that has air flowing through it, bending it, flapping it, etc. I also have to animate it like a character. My idea was to create a soft body simulation of some sort that uses a sop animated cage as a target. If anyone would like to prototype it I am attaching a hip file that sets an example scene up. My intention was to post an example of where I was at but my attempts have been so unsuccessful I didn't want to contaminate everyone's thinking. The sop "TARGET_FOR_DOPS" is just a stand in for the keyframed animation I will need to follow. Thanks in advance to anyone with any ideas they can share. I'm very grateful as we are a bit of a pickle here. wind_sock.hip
  8. I'm new to Houdini, transitioning from Max(TP, pflow, Magma...etc.). I started by messing around probably how everyone else did by using the shelf tools. However, I'm now trying to really dive into it using the application as it is intended. I figured that I would start off with a very straightforward and simple example from scratch - NO SHELF TOOLS. What I did first was actually create what I intended to make using the shelf tools first and then see what was going on and then start from scratch. In my example I just want to Have a Torus fall and have particles emit off the surface as it falls. The Rigid Body part is working perfectly, but the POP part of it is where I'm having problems. As soon as I add POPS into the mix (even if I make a different DOP network) I keep running into the problem that the particles seem to emit from a "ghost" of the torus geometry. One thing I noticed and can't seem to find an answer for are these 3 things. When I use the shelf tool to emit particles from the surface, it fills in information into the "DOP Import" Node that it creates. The information is created in the Object Mask of the node. I can't seem to find what an Object Mask actually does (I'll revisit this later). The shelf tool creates a SOP node with a DOP I/O and I don't know why. When using the shelf tools to make this setup, I noticed that If I deleted the information that was in the Object Mask of the DOP Import node at the end of the tree, the particles in the DOP Network wouldn't work at all. To revisit, what I was saying previously - I don't know what an Object Mask does/is for, and the information that was added when using the shelf tool route looked incredibly arbitrary to me. I included some images of my basic setup. Here is the top level Object view: You can see what I'm talking about where the torus falls, but the particles are emitting from the "Ghost" geo. This is where I suspect something is wrong, If I had to guess, the Object Mask has something to do with saying to use the geometry but not interfere because it's a mask? (I have the DOP Import node set to Bypass so that everything would show up.) And lastly, here is my DOP tree. When I select the Torus SOP this is what happens. But with the shelf tools, it used info in the Object Mask as the SOP Path. I know this is super detailed for such a simple setup, but I'm trying to understand what I'm doing and also what/why Houdini is what it is. Any and all help is much appreciated as I've been looking for an explanation to this for well over a week. I look forward to having that moment when it all clicks. Thanks! -Stark
  9. Pyro with Pumps?

    Ok, so I have created a velocity field with a SOP network and I am trying to essentially have a static velocity field that the pyro is advected over. I will add noise into it manually later. The effect I will eventually be doing is to have a pyro confined within a similarly created vector field to the one that I have defined in this file. The primary issue is that I am aiming to animate the field construction eventually, which will definitely add a measure of complexity to it. The method that I am trying to accomplish is to have the entire vector field outside of the torus be directed in towards the R2 center and then inside be moved along around it. The velocity field that I have generated does this beautifully and exactly how I want, but when the pyro solver gets a hold of it, it advects it in some rather horrifying ways and makes it totally not what I am trying to do. What I need is a way to stop the pyro solver from advecting the velocity field and just move the smoke/fire through the voxels. I was looking at pumps and I feel like they might be a solution, but I am struggling to figure out how to get them to work. The example videos I have seen online show effects similar to what I am trying to achieve, such as smoke rising around a helix and such. Can anyone direct me to how to make them work or a tutorial on how to do this. bendingfire_386.hipnc
  10. Import Velocity Field into Pyro

    I am trying to accomplish an Ink in Water effect for a project in my course, and I have been instructed to use Pyro to do so. I am ok with this, as I have plans for my final project in the class that relies even more heavily on pyro to accomplish the effect, so learning how to wrangle it now will make it much better then. I have found a great source for my look development and sim development. I have figured out that I am going to need to create a vector space to control the velocity field of the simulation to really get the control that I want over the simulation, but unfortunately I don't seem to be able to import the field that I have generated in my SOP. The attached file has all of the vectors calculated and sitting on a SOP, but I only seem to be able to use it if I have it on the generating geometry, which I want to be separate so I can make it look like an injection into the volume instead of the volume creating it itself. This is actually a key part of my final for this class that I need to get the kinks worked out now, so I can focus on the individual problems for that project. So what am I missing in this DOP network? velocity volume test.hipnc
  11. RBDs and Field Forces

    Hi all, Hopefully a simple question... how can a single RBD object get affected by a Field Force in such a way so that it spins? See attached hip file for the following discussion... I've set up a vector volume with vectors that push in the +ve x direction in the lower half of the box, and in the -ve x direction in the upper half. I've used this volume to create a Field Force. In the middle of that, I've placed a single RBD box. There's no gravity or ground plane. When I simulate, as far as I can tell, the rigid body only samples the Field Force at its center of gravity as it just starts to drift in position slightly. I would have expected the box to rotate a lot! I have a few questions: Is there a way of getting the RBD box to add up contributions across its surface to respond correctly to the field force? I should be developing a lot of torque on the box from this field. I tried playing with the Sampling parameter. Switching between Point, Circle, and Sphere, but they don't make a difference. How is this parameter supposed to be used? The Field Force node seems to respond to any SOP Vector Field I plug into it without worrying about the name of the volume I create in SOPs. So what's the purpose of the "Force Attribute" and "Torque Attribute" name parameters? How can I add torque? Think that about covers it. Thanks for any help you can give Ta! Andy field_force_test.hip
  12. Smoke from Scratch Difficulties

    Hello everyone, To get a better understanding of how a smoke simulation works, I wanted to try & make the standard smoke setup from scratch rather than use a shelf tool. I built a simple logo reveal in C4D, with the intention of pouring smoke out of two pipes. I exported that via Alembic, and imported it into Houdini. I've gotten to the point where I feel like I have all the correct nodes in place & hooked up, with all the settings where they should be, but no smoke is being generated. It's an incredibly simple setup, but I'm missing a key piece somewhere - and even after comparing it node-by-node to another setup that works, I can't seem to find the problem. The source file is attached, and the alembic is linked to below. I've organized the file to make it easier to look through. Any help would be appreciated! https://www.dropbox.com/s/0pcdlptp9tcic9j/Forge_05.abc?dl=0 Thanks! Luke Forge_01.hiplc
  13. Trouble Weird with Mask Field

    Hey Everyone, I am trying a test with the mask field. I am trying to mask the Gas Blur solver by a volume from sops. The result should be a smooth look near the emission source and then outside the mask field you should see a bunch of disturbance. I took a look at the example attached with the Mask Field node and set my test up in similar way but for a reason I cannot find the mask field is not working. What am I missing? I get the feeling that the disturbance and gas blur are working against each other or the MaskField is being erased before it reaches the Gas Blur. File is attached and Image for those too lazy to open the network. I will be available to answer any questions. smoke_gasblur_mask_not_working.hip
  14. Hi I am trying to dive into VEX. And I made up a little assigment for myself - do an assemble effect in DOPs. However when matching target position and orientation there is a slight offset occuring in orientation. (img_1) But if I do this position and orientation adjusting (same method) based on simpler rule (frame number) it works as expected. (img_2) Could somebody look into this file and check what may cause this problem? Thanks, Juraj project.hipnc
  15. Hello Community, Been looking and exploring nodes for a while now and I cannot find the answer to this problem. How to apply a force to an object in it's own local frame so even when I do rotate that object, the force is applied let's say in the y axis. To give you guys some context, I want to model a quadrotor, and have the guy have 4 propellers in which I want to put uniform forces to each of them to drive a point in the quadrotor. Then, by modifying the values of the propellers, I could eventually model it's yaw, pitch and roll with just forces and torques. But all the force nodes I seem to explore are in the GLOBAL frame and you apply it to the absolute y of Houdini and not to it's local y. Any idea how I can solve this?? Thanks a lot once again! Francisco.
  16. First of all, I want to tell you what end result I want so you can solve my scene file or suggest other easier way of doing it. I want to get the transformations of these rbd dominos to object level. My first approach was to simulate rbd fractured objects then use dynamics chop to get that data and export it to object level but it got some problems. My second approach was to "get point data" from dops and do some matrix magic in VOPSOP with points and import that data through geometry CHOP so it can get exported to object level grid's transformation. I have tried to use orient attribute to my advantage but objects behave weirdly. Their positions are wrong. This is good exercise for you to use SOPs, DOPs and CHOPs interconnectively. You can see my file with both approaches, check out these nodes and tell me what am I doing wrong? I just want to apply the boxes domino data to grids in object level. Thanks! dynamics orient.hip
  17. Hi, I'm using a gasfieldvop and would like to sample one of the simulation fields from an arbitrary P. The obvious way is to use the volume sample or volume sample from file VOPs. However, I'm not sure of the best way to access the desired field from the volume sample VOP. My current working solution is to dopimport the desired field into a sopnet and put a pointer to that op into sample volume from file. Works OK, but this feels pretty convoluted. So, is the a more straightforwad way to directly sample any field within gas field VOP? Thanks.
  18. I thought this would be relatively easy but I've spent all day trying to figure it out and failed. I have a cable that I need to swing under an animated object. The cable is attached at both ends so it is the loop that is swinging. I tried this with a wire solver and it worked fine. The problem is that the cable is supposed to be almost solid in it's rigidity and no matter how high I turned up the stretch and bend values I couldn't achieve this with the wire solver. The cable only needs to swing from side to side so I thought an RDB object with a hinge constraint might do the job instead but as I quickly found you can't attach a hinge constraint to a moving object. Is there a way to do this?
  19. Dynamic constraints creation

    Hi, perhaps I haven't looked hard enough, but I can't find any examples of dynamic constraint creation for bullet RBDs. Removing constrains is relatively straightforward, using a SOP solver in DOPs. Likewise, adding constraints defined in SOPs for new rigid bodies is easy enough (just merge the defined constraint prims from SOPs into the constraintnetwork geometry in the same solver). However, I'm having trouble trying to figure out how to generate constraints on the fly, between any two rigid bodies, without statically defining the connection in SOPs beforehand....any ideas? I'll whip up an example HIP when I can.
  20. Hi everyone, Im working on a project where I will need to build a lot of wires which will stretch and eventually snap, like pulling steel cables apart or tearing tendons. I am attempting to do this with the fracturing parameters in the wire object but it does not work. Does anybody have an example of being able to break a wire using the wire fracture? Or is it easier for me to just use the pre-cut wire and animate a glue constraint? Any help at all would be great. Thanks! breaking_wire_RND.hip
  21. gas fluid resize artifacts

    Has anyone else encountered artifacts with the Gas Resize Fluid Dynamic node? I've attached a simple file that shows what I'm talking about. If you dive into the dopnet, view it from the top orthographic view, and play the first 20 frames or so, it's clear that the fluid is developing grid-shaped artifacts that are *larger* than the resolution of the fluid itself. If you enable the timewarp node inside sphere_object1, you'll see that the artifacts still develop, but much more slowly. So it seems to be related to the rate of change of the size of the fluid. artifact.hip
  22. Hi everyone, I am trying to simulate a bacterial growth scene by using wire objects. In story short i am splitting a wire object every 15 or so frames and getting an exponential growth. But my problem is that, i want the new split wires to try to come to constant length (like a pressed spring). and i want them to push each other away. Please take a look at my file. Am i even in the right direction?. how can i make the lines grow back to a size? by giving them a rest position every frame? thanks in advance. bacteria.hipnc
  23. Hi Guys, Missing some basics here.. I want to be able to Visualize force vector field from, lets say Gas Vorticle Forces (using vector field viz) and Modify ( gasfield vop/wrangle) it pre solving step. How do I go about doing it ? Thanks, -GM
  24. I have a RBD sim, with 1 packed object which contains 9 elements. I am trying to disable the gravity only on certain elements, within the packed object. In order to achieve this, I would like to control the gravity node with a dop group. I created a point attribute "falling" which I control in a sop solver, within the dop network. Then I created a DOP Group that creates a group based on the following expression: point($DOPNET+":"+$OBJID+"/Geometry",$OBJ,"falling",0) Now, this seems to work but ...not quite. I see elements that start fluctuating at a certain moment, but this moment doesn't match the moment when the "falling" attribute is triggered to 0. To start, I'd like to understand if I am using the above expression correctly. I am quite confused with the global variables $OBJID , $OBJ used with Packed Objects. Could anyone shed some light on this? I am on H13.0.547
  25. Wrecking Ball Constraint Question

    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