Jump to content


  • Content count

  • Donations

    0.00 CAD 
  • Joined

  • Last visited

  • Days Won


Everything posted by loudsubs

  1. Optimize Pyro Container, H17

    Been trying to crack this one since they changed the sourcing. Few variations here. Done in 17.5 vel_test2.hip
  2. ffmpeg multi file output top

    Guessing here, haven't tried this for writing videos - Partition by attribute, and make sure the attribute you're wedging is in the filename. Then you should get 3 different files.
  3. vellum dynamic constraints

    I have basic tentacle-type setup, that's what I'm going for anyway... I'm creating dynamic constraints from a cluster of vellum points that are pinned to some SOP animation, and attaching to some vellum softbodies with no pinned animation. Done using the 'attach to geo' option on the vellum constraint DOP. The constraint creation is working, but I want the soft bodies to get pulled into the points that are creating the dynamic constraints (like tentacles pulling something in). I've tried by manipulating the rest length, but that doesn't seem to have any effect. Anyone know how to get this to work? Thanks! vellum01.hip
  4. Houdini 18 Wishlist

    GPU mantra GPU sparse smoke solver. Like the one this guy made Some love to the CHOPs animation tools, for non-animators (ie: spring, jiggle). Ways to make it easier to procedurally (group?) effect only certain parts of the incoming data. More control and options to fine-tune when using spring, etc.
  5. Yeah that's pretty much it, make a simple scene and test it. Think of it like doing vector math in a vopsop. the gradient fiield is a vector, and you can add it to the vel field which is another vector. You can also mulltiply a vector field by a scalar field, (ie: temperature). That is how buoyancy works in a smoke sim, there is a bouyancy direction (a vector), and it gets multiplied by a scalar field, temperature, which controls the magnitude. The control field parm of some of the shaping tools is indeed a mask, almost like a group field in sops. It wants a scalar field like density or temperature, or something custom like fit length of a curl field (which you could get with a couple gas analysis nodes and a gas vop) You dont really need to mess with the bindings tab often. You can do some of these operations with vdbs in sops (vdb analysis), and then lookup the volume values on points that are sitting in the same position using a pointvop and volume sample. This can be a good way to inspect the numbers more if youre trying to figure what exactly the calculation is doing
  6. Gas match field will let you create a new field and gas analysis will do a specific calculation, such as find the gradient or curvature. It's similar to the vdb analysis. Then gas calculate lets you do math operations, such as combining fields by adding or multiplying, etc. So if you had a FLIP sim, you could use a gas match field to create a new field, using the flip surface field as reference. Then you could calculate the gradient of the surface, and store it in that newly created field. Make sure to pick the right class of field for the new field, based on the operation you'll do with the gas analysis. Ie: to store a gradient calculation, it needs to be vector. Now you have a vector field, based on the gradient of the flip surface. You can use a gas calculate or gas linear combination (preferable for simple operations) to add that field to vel. Also, there's a masterclass called 'building fluid solvers" or something like that. definitely worth checking out.
  7. dynamic bones

    I'm working on a project where I need to hand animate a snake-like character doing spirals and twists. Investigating approaches, I came across this video, where the guy basically gives a bone chain wire dynamics, and is able to get some really nice overlapping tail motion, just from animating the root of the chain. At 9:00 of the video he starts to add dynamics, and you can see the animation effect I am trying to achieve at 12:50. My goal is to find the easiest way to get overlapping tail motion, by animating just the root. So far I'm just trying to get a wire to behave nicely and not explode from a simple sine wave animation, nevermind getting the bones to move with it. Any rigging experts have advice on how to approach something like this in Houdini? Thanks!
  8. It would definitely be nice to have an input for pivot on the rotate function... The work around I do for this: Store the original pivot, move each box back to origin by negating the orig pivot, perform the rotation, then move the boxes back by adding orig pivot. Did a few example notes in your file. matrices_a.hipnc
  9. Opus Pattern Grid

    Playing with Konstantin's setup with an extrude sop and a for loop
  10. Create multiple FEM over time?

    Regarding the interpenetrations, try using higher res geo, and more tets. I had a clip sop in thst scene to visualize the inner tets of the sphere. Experiment with the sphere resolution and "quality" tab on the tetrahedralize sop. That's what I'd try before getting too crazy with substeps
  11. Create multiple FEM over time?

    More efficient to leave the creation frame parm alone, and just create one solid object at the start of the sim. Then keep merging new geo into it with a sopsolver fem_createmultiple.hip
  12. here's how to do it with pyro instancing. I rarely use this method though, because I can't push the res of each instance as high as if each were an individual sim. And if one cluster needs tweaking, you have to redo the whole thing. Most of the time, I'll make a similar setup, but wedge through each container on the farm, as individual sims. Couple things: Each instance point can only be on for 1 timestep, otherwise you'll get mutiple containers on top of themselves. view the dop details view during the sim, to verify the new smoke objects are getting created you need 1 sop volume w/ different name, going into dops for each instance container. The fluid source sop will create and partition using the "cluster" attrib "continuous" needs to be on in smoke object instance tab to have new containers birth mid-sim you can control containers size on the instance points with the "scale" 3fv attrib. I think theres info in the help card too pyro_cluster.hip
  13. Houdini 16 Wishlist

    Thanks guys, yeah I probably just need to spend some more time coming looking into what's possible with the energy and fracture threshold attribs. And thanks for posting the FEM denting examples too.
  14. Houdini 16 Wishlist

    This screen shot is from an old cloth video, possibly Houdini 11 or earlier. Can we get some of these old features back into the current cloth solver? Specifially I'd really like to be able to access the internal force attributes, so that they can be used to create other secondary effects, dynamically, such as tearing. Plastic deformation would also be welcomed with open arms.
  15. VDB Advect SDF

    The volume being advected needs to be an SDF. You had it set to fog, and then you were converting it to a regular Houdini volume. Needs to be a VDB, to work with the VDB advect node. AdvectVolumebyVolume1.hipnc
  16. I don't think there's a huge difference between using a delayed load shader and using the 'packed disk primitive' option on a file sop. they are both reading the geometry from disk at render time. Also, keep in mind that your geo doesn't have to be a 'packed primitive' to be loaded as a 'packed disk primitive'. They are 2 different things. I don't really use delayed load shaders anymore because they take more steps to setup. Packed disk primitive seems to work just as well, and you just have to change the drop down menu on the default file sop. easy peazy.
  17. Houdini 16 Wishlist

    A textport 'vexhelp' command. Identical to the textport 'exhelp' command, but brings up vex expressions and an actual example of using it. I find the help browser just doesnt work sometimes, or can take a while to load. probably a network thing, but it would be great to be able to access vex info and examples faster.
  18. Houdini 16 Wishlist

    It's be great to have a basic volume shader, that has an identical interface to the volume visualization SOP. And have a button on both the SOP and the shader that can easily transfer the settings from one to another. With the way things are now, it's possible to set the visualization settings 3 times, (inside the sim, in SOPs, and then in the shader). Pretty redundant, there should be a lot simpler and faster way to get what you are seeing in the viewport, into the render
  19. Constrain doesnt work

    With cone twist and hard constraints, I always make the length zero. I've found exploding constraints usually have something to do with the rest length. So I always just set it to zero. Made a few changes to your file, including using a facet to get unique points. then the primitive sop can actually scale each prim down to zero length. constraint_a.hipnc
  20. [SOLVED]Cloth Creation Position Points?

    check out the example hip in this thread.
  21. I came across this video the other night, and thought it had some really cool effects. It's done in 3DSMax. I'm trying to work out how I would approach this in Houdini. Right around 23:00 - 24:00 in the video he has some playblasts of what looks like an RBD sim turning into cloth, which continues to fracture after the initial hit. There are obviously multiple layers in there with the particles etc, but the part I'm interested in is the continuous fracture of something that has weight and mass, but seamlessly turns in cloth/ash. I think I would first try to do this with all RBD, and cheating gravity after the initial hit, not sure if that would give the right feel though, of lifeless ash blowing away in the wind. I am also curious about the idea of turning a fractured RBD into cloth, in order to get some nice bendy behavior as it turns weightless and blows away in the wind. But since the thing continues to fracture, things get complicated. What do you guys think?
  22. Transform packed RBD pieces

    I'm trying to figure out the best way to transform packed RBD primitives. I'm doing this by modifying the packed primitive intrinsic 'transform'. The issue I'm wondering about, is that the collision hulls that bullet is creating (packed rbd object > bullet data > show guide geometry) change every frame, which seems weird. I want to create the collision hulls on the first frame, and then transform those shapes. I've tried 2 different ways in the attached file. One I set the 'initial object type' to 'create static objects', and then I transform them inside the sim using a Geo VOP DOP. The other way, I'm setting 'initial object type' to 'create animated static objects' and feeding in the transformed pieces straight into the sim. Both produce the same result, and the collision hull seems to get updated each frame. Is there a way to make sure the collision hulls not update each frame, but still give them rigid transforms? Thanks! xform_packedRBD.hipnc
  23. more sand/grain question

    Here's one way of doing it. If you want the sand to gradually blow away, you probably dont want to reference @P.y inside the simulation to drive the force, because thats going to dynamically change during the sim, and if a particle gets outside of the threshold, the force could stop affecting it. So I here created a group in SOPs that grows over time based on the Y bounding box. It gets referenced in the DOP sim, and then particles always stay in the group once they have joined. If you want to add more forces using a POP VOP, make sure the noise is set to 3D noise, and then add that to @force, and put force_grp in the group parameter of the VOP. sandtest_forceRandom_01.hiplc.hipnc
  24. Hinge Constraint Issues

    Hey Tomas, thanks for the example hip! I had a question about what you're doing with setting @orient in the wrangle. It seems to effect the range of rotation within the simulation. When I change the radians value in your vex code to 10 for example, the constrained objects no longer rotates as far as with 90 for the radians. I can see that changing that value changes the cone twist guide in DOPs. Skimming through the help card for the cone twist constraint, I don't see where it mentions using @orient anywhere. Can you explain what's happening here and how you knew about this? Thanks!
  25. FEM constraints H15

    The reason it wasn't working for you, was you need to convert to tets, and then create @pintoanimation. When using FEM, your geo has to tets for the sim, and then you convert back to polys after. Check this hip, I played with a few variations for both @pintoanimation and @targetv/P FEM_pin_a1.hipnc