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About nuki

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    Martin Kenzel
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  1. Repulsionpak

    you could do that with 3d packing. They showcased that in the h17 launch presentation, its at minute 51:
  2. 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.
  3. 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
  4. randomize density methods

    You could take a look at wedging: https://www.sidefx.com/docs/houdini/tops/wedge.html
  5. 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.
  6. Delete grains from existing hole ?

    You have to make a watertight mesh that fits the hole like a plug. If you used a polyextrude, let it output the Sides Group, isolate those faces and polyfill that. Then create a vdbfrompoly, like in the attached file sdf.hiplc
  7. Delete grains from existing hole ?

    In your case, couldnt you just kill them if they hit a P.y threshold? Otherwise you could create an sdf for the hole and kill them inside a sopsolver if the volumesample() of the particles P is < 0
  8. Swap packed fragments via intrinsics

    Neat, exactly what I was looking for! I suppose there is no similar workflow to use with Packed Memory Primitives?
  9. cluster constraint

    Like this! Steven Knipping got a great series on Bullet / RBDs. Credits to him for the method showcased in the attached file. clustered_glue.hiplc
  10. Constraints between individual objects pieces

    if I understand you correctly, you can use the "Find Boundary Connections" option of connect adjacent pieces. Alternatively you could also pack your fragments once more, using a 'name' attribute unique to each object. That way the constraints would be created only between the two objects' centroids though. See attached file: bound_const.hiplc
  11. Swap packed fragments via intrinsics

    It would work, but its not the ideal solution for what I'm after. To tell a bit more about the setup: I generate N uniquely fractured walls first. At that stage they just sit at the origin and I generate hi-rez pieces for each wall there. Afterwards I place the walls, randomly selecting one of the prefractured walls to avoid repetition. Then that goes into the sim. The problem with transformpieces is that my source geo (the hi rez pieces) only contains a single copy of each fragment of each wall. I could use an instance or copytopoints sop to re-place and re-duplicate the hi-rez fragments to their respective lo-rez fragments. However, I was hoping to ultimately swap out the fragments only at rendertime (Mantra) using a geometry shader. I dont see how it would be possible to do the copy/swapping inside a procedural geometry shader and I figured doing it via Intrinsics would be the simplest and cleanest way if at all possible.
  12. I want to get Houdini to fetch 'piece0' from geoB' instead of 'geoA' by modifying the primintrinsics of the packed fragments. Since its possible to alter the 'fragmentname' attrib I assume this would be possible, but I cant find out how houdini keeps track of the 'root' of the packed fragments. Seems like the 'path' attribute doesnt have any effect and geometryid is read-only. I was hoping to find an efficient way to swap low-res sim fragments with their respective high-res versions. Any suggestions?
  13. In fact, I have yet to find a operator definition type that has the 'New Output' option unlocked??
  14. As the title says, when I create a new Material VOP asset the 'New Output' option in the Type Properties is greyed out. If I define export variables inside my surface shader code the 'Shader Call Export Variables' VOP will not bind them. Assigning values to eg. Cf directly in the VEX Surface code does nothing. How could I output eg. a vector from a Material VOP Asset?
  15. I am doing some shader building for fun and ran into trouble fetching parameter values with the chs() function in a snippet or inline code vop inside a material builder. I just want to get the path string specified in the 'txt' parameter of the parent node, but chs('../txt') returns an empty string. As you can see in my small example file the whole thing works fine when doing it in sop land with an attributewrangle. Since the wrangles are just snippet vops I dont have a clue what I'm doing wrong....maybe a context/bind issue? The compiler flags are identical on the wrangles snippet vop and the one in the materialbuilder. Also, since printf() doesnt output anything from the materialbuilder I was hoping for some tips on getting var readouts for troubleshooting my shader.cheers! vop_param_test.hiplc