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Everything posted by nuki

  1. centroid in pointWrangle

    promoting P to a detail attribute (by avg, min/max etc.) can be a useful trick too!
  2. Pin Attach Constraint RBD object

    ah, its the constraint force mixing - which is enabled by default for hard constraints on the solver.
  3. Pin Attach Constraint RBD object

    hm, if i use my exact same setup, just with bullet sops, the whole thing gets unstable af. Raising constraint substeps helps a lot, but I cant get completely rid of the jittering. constd2.hiplc
  4. Pin Attach Constraint RBD object

    I would use a hard constraint with type set to ''position'' for the hinge. For simple one-way collision with the fluid I'd mesh the fluid, convert that to vdb and get a collider for bullet with vdbtospheres. eg. like in the attached file it would probably be a good idea to match the flip solver substeps to the bullet substeps. constd.hipnc
  5. Volumesample with Noise

    @drøgö sorry for taking so long. What I meant was that, since SDF values just store the distance to the closest surface point, you can just subtract a fog volume from that SDF in order to dent it. Its scale dependant, but that could be compensated by using relbbox.
  6. Volumesample with Noise

    I am following this great talk by Saber Jlassi where he uses noises to distort a volume (around 7:30). I do understand that hes using the aanoise to change his lookup position for the worley noise, but I dont get how he proceeds from there. Volumesample requires a vector input and I dont get how he generates a meaningful position vector from the single float output by the worley noise. volume_rock.hipnc
  7. expression for fit range

    use this: s@constraint_name = 'ramped_glue'; s@constraint_type = 'glue'; f@strength = fit(v@P.y, ch('min'), ch('max'), 0.0, 1.0)*ch('strength'); in a primitive wrangle. Instead of just multiplying by the 'strength' factor, you could set out_min and out_max instead of 0.0 and 1.0 constraint_ramp.hiplc
  8. Pumping Vellum Cloth

    I am testing a cloth sim on this simple mocap dummy and get this weird pumping throughout the sim. My initial suspicion was that it was caused by the framerate of the alembic cache I use as a collider, but that seems to be interpolated nicely when inspecting with float frame numbers. The alembic cache is around 50mb so heres a OneDrive link to a cleaned up scene file. Theres really nothing beyond basic going on in this scene so I guess it would have to do with the cloth constraints. Since I'm new to vellum any suggestions on how I could get rid of that pumping (preferrably without filtering -> collisions) are really appreciated. scene file rr_test_v002.mp4
  9. Pumping Vellum Cloth

    Because filtering does distort the mesh a little I presume?
  10. Pumping Vellum Cloth

    @Noobini thanks for the file - I will have a look in the evening! I did play around with attach to geo constraints, but deleted all of it in this simple example to exclude it as a possible source of error. I think you may be right about lowering the substeps since the pumping got worse with increasing temporal resolution . In the end I will probably need substeps tho because the whole thing should playback at 60fps. @anim @Atom I still have to familiarize myself with chops, but it seems super useful for that kind of stuff. The Mocap data is baked from a retargeted HIK in Maya, so theoretically it would also be possible to do the filtering there.
  11. How to randomize seed value on the scatter node

    You can use foreach loops and their meta import to do just that. Check out the detail() expression reading the integer number of the current iteration to drive the seed. The copytop oints node can even pack the geo for you. test.hiplc
  12. Add sop creates a polyline between the points in order, the scatter sop randomizes point order by default hence the messy appearance. You could do branching lighting with some vex growth, an l-system or shortestpath sop. One approach might be:
  13. Or use "Packed Disk Edit" sop, does the same as Neon Junkyards suggestion. Both work only for packed disk primitives - curious if cwhites python method works on packed geo/fragments as well.
  14. alembic objects into copy to points

    I think its this one:
  15. Realistic Mud with PBR & Mantra

    its probably the lighting and perspective you need to match more closely. The reflections in the reference look overcast, so try an overcast sky instead of your sunny one.
  16. HDRI render issues

    is it even emitting light or just visible to reflections tho? maybe the shaders have high reflection/low diffuse. hard to say without scene file.
  17. did you set the type in the bind export correctly? There is a setting to inherit it from the input value.
  18. If you could share the exr file it would be easier to troubleshoot. Looks like it would be a colorspace/gamma issue. Wtf is that filename btw
  19. Repulsionpak

    you could do that with 3d packing. They showcased that in the h17 launch presentation, its at minute 51:
  20. Render Smoke Question

    so you have image A and want image B? The main difference between the two seems to be the density of the smoke sim.
  21. Motion Blur pass with mantra issue

    iirc you will have to enable velocity blur on the geo, enable motion blur in the mantra rop and disable 'Allow image blur' v_pass.hiplc
  22. randomize density methods

    You could take a look at wedging: https://www.sidefx.com/docs/houdini/tops/wedge.html
  23. UV Flatten distorted plane

    I am trying to generate nice, relaxed UVs for a distorted grid object. Ideally I would want to simply relax the initially generated UVs after distorting it but all the tools available seem to be focused on generating new UVs altogether. Having never done this kind of thing in Houdini I also struggle to understand how I could procedurally constraint eg. the outline of the grid to a square or all the points with @P.x==0 to a straight line. UVs pre distortion UVLayout post distortion Quickly generated UVs in maya to outline what I'm after river_UV.hip
  24. Seeking Solver Writing Advice

    I am not great at maths, but isnt 'accumulating' values in a solver node simply euler integration? Since your r depends on v and v depends on a which you are accumulationg, I'd say you are already using an integral to find the displacement. I'd love if someone confident in this matter could verify this.