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Everything posted by IhabAli

  1. Hello, i have a setup using instancing from the vellum source node. I’m essentially using single point each frame to instance a vellum patch. The trouble is, if the instance happens to be created intersecting with an already instanced patch the they seem to weld together. It’s not actual welding but I think the collision algorithm just gets confused and keeps the overlapping surfaces stuck together as it tries to minimize intersections between the pscales of these points. Is there anyway to resolve that?
  2. Nuke from TOPs generic processor

    Hello, Does anyone know how to appropriately run Nuke in execution command line mode(-x) from the TOPs generic processor? On my end running 18.0.391 the tasks keep failing but the log shows nothing expect the typical Nuke command line startup messages(version and build information and nothing else). When I wrapped the Nuke command line in a shell script and ran than I see that I'm getting a segmentation fault I'm assuming from Nuke and that's why the process fails. Any ideas?
  3. Hello, I'm looking for a way to essentially implement texture baking in SOPs. I came up with the attached solution using uvsample on a map loaded to a grid object where each point represents a pixel in the desired texture resolution. For some reason this simple approach seems correct to me but doesn't work. Any idea what I'm doing wrong? Projector.hipnc
  4. Streaky Portal Effect [SOLVED]

    Hello All, I'm trying to achieve the same effect of the attached portal reference video specifically the hair like edges shown in the below screenshot. can achieve the general fluttery movement in a pyro but the core of the "stringy" edges appear to behave like a violent FLIP splash. The closes I got was advercing a POP sim with velocities from a fluttery smoke sim and applying POP fluid and converting the particles back into a fog volume with some velocity noise and velocity motion blur but it just doesn't look nor move right(see stringy.mp4). Any advice or recommendation would be highly appreciated!!! Video Reference for the Effect: effect.mp4
  5. Streaky Portal Effect [SOLVED]

    I'm putting this out here since this thread keeps going off topic I managed to recreate the fine hair like tentacle details by dividing the simulation into much smaller segments, using much smaller noise scales in the pattern driving the attribute based emission of the flip fluid. With a bit of tweaking on the viscosity and the simple custom cooling wrangle(see my original file in this post), the smaller segments are able to consistently hold hair like details as the flip fluid breaks under the turbulent forces added to the solver. Next I implemented a simple looper for the simulated segment by just cross fading the particles' alpha(or any arbitrary attribute that would eventually drive opacity in the shader). Replicate these around any shape(example below using a for loop, copy transform, and some iteration based instance randomization for time offset). The results below are rendered in Renderman. Obvisouly this is based on a single simulation run but much better results can be achieved by running and looping multiple independent simulation seeded differently. This is a perfect application for PDGs. I ' ClusteredSim.mp4
  6. Streaky Portal Effect [SOLVED]

    Thanks @Atom, I know how to build it, I was just being lazy I'm still working on a customization in the vellum solver for wire breaking in an attempt to create even more fine details. Nice tutorial BTW!
  7. Streaky Portal Effect [SOLVED]

    @Librarian my setup was shared from the very first post. I’ve just been tweaking parameters and resolution
  8. Streaky Portal Effect [SOLVED]

    Nice @Atom, looks very similar to the inner layer. Are you using smoke only or still running the wire sim? I'm getting very close to reference with my custom FLIP solver. If you want to share your file I can combine the two EvilPortal test.mp4
  9. Streaky Portal Effect [SOLVED]

    Nice! I’m trying to see if combining my original flip setup and a Vellum based wire solver would get closer to the reference.
  10. Streaky Portal Effect [SOLVED]

    Thanks @Librarian. Yes 3 layers 2 of which are fairly simple to analyze and implement(the smoke like ring pushing outwards and the red firey "energy" pushing forward). The black streaky hair is what I've been asking about. Advecting particles by VDB is essentially why I decided to go with FLIP just so I don't have to implement things like velocity field smoothing and viscosity from scratch. Basically the "hairs" are behaving like particles driven by a non-divergent velocity field because of the way they fold and swirl around(at least that's what I think). Pyro won't be sufficient on it's own because of natural diffusion that occurs from non-divergent projection in the velocity field and particles would be the way to maintain details. I understand all of that and my conclusion was just to use flip because it's basically a combination of POPs and Pyro. I've posted my simple implementation of a customized FLIP solver to show how I was approaching this effect but I'm struggling with the LOD. I'm specifically looking for techniques or idea to achieve hairy streak like patterns in FLIP or otherwise a completely different concept of achieving dynamic abstract hair like patterns I guess. Thank you once again @Librarian!
  11. Streaky Portal Effect [SOLVED]

    @Librarian this looks like a simple pop simulation driven with some turbulence source point velocities. Not really related to the video reference I sent. I appreciate your help but I'm looking for a way to achieve the level of complex details while maintaining the fluid like movement of those hair like fluids. Anyone else?
  12. Streaky Portal Effect [SOLVED]

    Getting closer to the reference using flip and attribute controlled viscosity. The tentacles in my setup seem a bit bloby, more like liquid than hair. Do you guys think the insane amount of tiny strands like in the reference is a matter of increase the flip resolution? Do you think with the basic dynamics in place the rest of the fine details are shader based? I've attached my setup in case someone is able to improve on it and provide some guidance on how to get more hair like details in the FLIP sim. Appreciate the feedback!! Stringy2.mp4 lavabased.hiplc
  13. Streaky Portal Effect [SOLVED]

    Thanks @Librarian. Not sure how the spherical force applies to the stringy fluid like effect in the reference. Perhaps I missed something in the file? The spherical trailing pop sim is very cool looking btw, so thanks for sharing anyway!
  14. Python from Gplay?

    Is there a way to run python inside a gplay session? I'm exploring an idea that requires UI events in gplay to generate simple viewport transform information in order to automate some tasks in Houdini(e.g. using python to recook a pdg network). It doesn't even have to be gplay, I'm just looking for a way to launch the houdini viewer port to view a scene file and for example upon closing the viewer it would force recook a PDG or run a script in houdini passing on the last viewport transform information.
  15. Pyro solver w/Feedback collision

    Hello, Any idea what is creating the collision surface seen by the pyro or smoke solvers when used in conjunction with the bullet solver in a mutual relationship and feedback forces are turned on? I'm trying to debug the collision shape that appears when I turn on feedback and it doesn't seem to be coming from either the bullet or pyro/smoke solver streams. I've attached a simple scene to illustrate. windtunnel.hiplc
  16. Hi, Wondering why when the an incoming velocity field to a dop simulation doesn't "move" while being self advected unless there is a project non-divergent in the sim. In a barebone smoke sim, I can advect incoming scalar fields using a velocity filed imported from SOPs, but when I try to advect the velocity field by itself, the velocity field doesn't seem to move inside the smoke object container. Regards, IA
  17. I actually found the culprit right after I submitted my reply HDR textures under 3D was not set to full HDR (it was at 8bit). For some reason that displaying banding with this particular attribute sampling method.
  18. Hello, I'm trying to build a setup that would move volumetric noise along the spine of a sweep object, effectively changing the coordinate system of the noise to be based on an object, at least in 1 axis. I set this up using the following simple network: Inside the volume VOP I'm finding the nearest point to the voxel and getting its curveu parameter value Problem is I'm getting this strange quantization in the volume for some reason Even through the curveu on the points appears smooth: I checked 3D texture and visualization settings but they don't seem to have any effect so I'm fairly certain this is not a viewport issue. Any idea what's happening? Regards, IA
  19. Thanks JO. Not much going on with import point it's basically just the point() vex snippet and I'm retrieving the attribute I need. Mantra appears to render this smoothly but the view port would also render smoothly a volume that is sampled directly from the position of the voxel(e.g. with a volume wrangle or vop that basically does @density=@P.y in the case of my example) I'm not sure I understand why this particular method of sampling the attribute and assigning to the voxel causes view port issues.
  20. HDA Viewer state node?

    Hello, I'm trying to create a digital asset that allows the user to user a paint curves on the surface of the input geometry. How would I set the the viewer state of the HDA to that of the paint node inside in the HDA's network? Thanks!
  21. Is it possible to simulate aerodynamic lift generated by vellum patches moving in “air”? In C4D there is a little option under soft body dynamics that emulates the effect of lift but I'm not sure how to do that with Vellum in Houdini.
  22. Hi, I have a file cache in a scene and for some reason when I try save to disk in background it terminates prematurely without writing any files. When I run it using “save to disk” it works perfectly fine. How can I find out what's happening when it's running in the background? are there any log files produces for the “hbatch” command? Regards, IA
  23. Vellum intersections upon instancing

    In case anyone is interested this is my temporary fix to the issue so that my patches don't stick together: I added a pop wrangle node after my vellum source to make sure this is the last step of the sim. Inside this is what I have if(@overlap_self>0&&@overlap_self<999) { @disableslef=1; } else { @disableself=0; } basically disables self collision if an overlap is detected...at least this is how I understand it. it seems to work..
  24. Hi, Struggling a bit to understand what's going on with quaternions and rotations but I'm basically trying to get a particle to point at its direction of motion in general but to constantly rotate around a certain predefined local axis. In the attached example I'm establishing orientation based on the velocity and setting up constant rotation relative to an object's coordinate system. All seems fine until the particle changes velocity using the pop wind. Not sure what's happening with rotations at this point, it seems to be working but things seem to jump abruptly at certain points. I'm guessing this has to do with matrix rotations but I'm not sure I fully understand the issue or how to fix it. particledirection.hipnc
  25. Sweep multiple curves?

    Hi, I'm new to modelling in Houdini and I wonder if there is a straight forward way to sweeping a cross section made of multiple closed curves to essentially create a thick and concave cross section. So for example sweeping two circles on a line to make a tube with thick walls. In C4D for example, connecting two such closed curves and running it through the sweep would automatically do that but in Houdini the only way I'm able to do that is to sweep each curve separately, create boundary edge groups for each resulting skinned sweep, then polyfill between the boundary edge group. Seems like a lot of nodes for a simple task Regards, IA