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  2. Flip Source From Points

    @Brickhouz: Did you check out the expert tips Noobini posted? It looks like Kevin Pinga suggests connecting a PopSource node directly to the sourcing input of the flip solver.
  3. Hi, I am making a rigid body simulation.I am doing a guided simulation,and the parts will follow the guide sim until they are active. The problem is that I can activate these parts when the center point(packed point)gets inside other mesh, But I cant find out how to activate when the piece gets inside even a little bit inside the other mesh like the picture I attached. For example,I want the blue parts and yellow parts(brown and maybe pink)to get activated if they get inside even a little bit inside each other. I hope someone could help. Thanks, Hiro
  4. Today
  5. setPointGroup behavior

    Most information are not Houdini specific but simply concept of programming for multi threaded execution. Primer is just an example of how following human logic can lead to wrong results. As it runs only one pass of your code and there is no mechanism to start multi threads from code, Detail is single threaded. But, in new version of Houdini you will see one more "Run over: NUMBERS" method which would allow multi-threaded execution. Well, that's depend on how coders of Houdini implemented synchronization of threads in that hidden part of code . At least, if your overall number of points is less than thread pool block size, that should work. First time sync among finished threads is done, rest (still unfinished) threads could have different result. But as I said, it depends on code implementation which is hidden from user. So things like: decision about of thread pool block size which will run in parallel, and possible synchronization barriers and possible different algorithms of handling divergent execution paths etc are not known, so you can not guarantee that such code will work in all cases. That is the reason why you should use number returned from that addPoint() function. Even if you know all of those things behind, that doesn't mean they can not change with every new version of Houdini so such "dirty" code wouldn't run properly in newer versions. These days almost every processor has several cores. Also modern GPU has thousands of cores. Separating an execution on many of them and execute in parallel usually means faster execution. How much faster, depends on nature of problem and code optimization for hardware specific advantages/limitations etc. If you want to learn more on that topic, google for CUDA, OpenCL, PTX, Parallel programming algorithms etc.
  6. HtoA Arnold Mesh Light doesn't work

    In your scene file, I placed a new poly sphere down, and linked to your mesh light. Worked as expected. In the image below, I just disabled the camera visibility for the light. When I opened your scene file, the sphere you were using was hidden, which also hides the affect of the mesh light. Not sure which forum hip files you're referring to. Hopefully this helps.
  7. Invalid Primary Token

    It "smells" like some disk issue, possibly lost fragments or even bad blocks but it could be also some bug from older version. Don't waste time searching details, try re-simulate scene on some other drive (or repaired) with latest version of Houdini. If that doesn't resolve the issue, then upload minimal scene which can reproduce error, here on forum. cheers
  8. Simple Circle Packing

    COVID19 Edition: now with 1.5m safe distance...or more...if you still feel unsafe vu_SimplePacking_COVID19.hipnc
  9. COVID19 related...or zit related ?
  10. Thank you very much for your input, much appreciated. I'm reworking my setup to incorporate this approach. My goal is to visualize vesicle fusion at the synaptic membrane, so Hawking is not too far off. This is an early test without transmembrane proteins:
  11. I've been working with a file for a couple weeks, versioning up frequently as I go. Never any issues with it until this morning. First it was crashing on stratup but I was able to isolate that to one of the ABCs it was loading (had never been an issue until today). I resolved that but now I'm getting an "Invalid Primary Token" error when I load a FLIP file cache. 95% of frames are as they should be but every once in awhile I get an empty frame. When I look at the files the are approximately the same size as their neighbors but the file cache doesn't seem to want to load them. I've tried saving out compressed and uncompressed--still getting the same errors. This is in Houdini 18.0.416. Has anybody run in to this and solved it before? I've run the sim a couple times and it still happens. Doesn't seem to be consistently the same frame. Thanks in advance for any help.
  12. find center point

    or use Extract Centroid SOP also you may need to copute orient to get stable reference frame in case you need it find_centerPoint_mod.hipnc
  13. find center point

    Hi Doanh, the attribute promote SOP can calculate the average of an (position) attribute. And a VEX solution would be to expandpointgroup(): int pts[] = expandpointgroup(0, 'group2'); vector pos_avg = vector(0.0); foreach(int pt; pts){ pos_avg += point(0, 'P', pt); } pos_avg /= len(pts); addpoint(0, pos_avg); find centerPoint_KM.hipnc
  14. find center point

    think there's a bazzillion ways to do this, I know one.... vu_find centerPoint.hipnc
  15. Hi everybody, I'm quite new to Houdini so I have a problem here. I have a group of points on a geometry. Now I want to find the center point of it so I can 'Copy to Point' a sphere. The geometry is an animated alembic cache. find centerPoint.hipnc BAZA_GUN.abc
  16. Flip Source From Points

    whatabout just a plain ol' box ? Copy a bunch of boxes to points>flip source....haha poor man's VDB
  17. Flip Source From Points

    metaball + copytopoints + flip source ? efficiency ? NFI !!!
  18. H18 - Problem Panning with Wacom

    yeah same here, i thought i was going crazy.
  19. Pyro Emission Animation

    nothing extraodinary here: scale:$F%24==0 (same expression in Activation works too)
  20. Pyro Emission Animation

    i just used the shelf>Flames (from a torus say)...then in source fuel animate the scale 0 to 1 to 0...blah blah...seems to work disclaimer: pyro noob.
  21. Pyro Emission Animation

    Hello, I've been looking for a way to turn an emission on and off. It seems really basic. I animated the activation and the scale source volume. It seems to animate the value but I never see a change during the sim. Could it be the multiple emitters from multiple source volume nodes? Thanks,
  22. Yesterday
  23. Apply attribute based on object id in RBD

  24. http://www.cgchannel.com/2020/03/10-expert-tips-for-better-houdini-flip-fluid-simulations/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+cgchannel%2FnHpU+(CG+Channel+-+Entertainment+Production+Art)
  25. Houdini 18 Arnold and Renderman Env.

    Thank you for the answer Atom. This is my setting. Its working.
  26. there's new workflow 'emit RBD' in H18 and also old school here
  27. Volume toon shader

    Thank you for responds. At first i thought transfer heat field to color and then to poligons, but then i sow this and decided make it it easer. Thanks.
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