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Posts posted by Atom

  1. Drop down an attribute wrangle that runs over primitives.

    Fetch the value using the point function and assign it to a new attribute.

    f@my_promoted_attrib = point(0,"my_point_attrib",0);

    You may notice the problem with this, however. I am fetching the attribute from point zero. So to do it right, you would have to loop over all the points for a given primitive and then average them to produce a single result.

    It just make more sense to use the provided attributePromote node.

  2. I suspected jitter in the walk animation, as well. I have never tried cleaning up an animation using CHOPs.

    I can fetch the geometry and drop down a Filter, but how do I route that filtered result back into the SOP network so it becomes the new animation?


  3. From my small investigation on this topic, it looks like Goleam can do more complex setups, compared to Houdini. For instance, you can't do archers in Houdini and turn their arrows into particles. I believe Maya can.

  4. It was recommended a few years back to try to simulate everything at real world size, but since then it has been discovered that Houdini has a "sweet" spot for simulation sizes. If you sim too small or too large, you have to use unreasonable separtions sizes and crazy collision resolutions that gobble up your memory. A recent trend is to simulate in the "sweet" spot and rescale your simulation to match your final world size.
    You can test this theory with your own scene. Scale your cups and emitter down to 0.03. This makes them the correct size for a cup to fit in one of the Default shelf tool character's hand. However, you'll quickly discover that you can't set the collision resolution small enough even if you decouple the collision resolution from the particle separation.

    While your scale is large and flip calculations are affected by larger scales, your basic setup works.

    Instead of adding wind to your simulation try replacing that with a PopDrag. This will slow down your particle movement, but you can boost the collision velocity scale to make up the difference. I set the Grid Scale to 1.0 to help with the fluid loss and enabled reseeding to smooth it out a bit.



    • Like 1

  5. Revisit the Delete node in your setup and visualize it by moving the Blue display flag.

    Set the Delete to operate upon points and in the group field add the popstream from the pop replicate. "stream_popreplicate1" Delete non-selected.

    This will give you only replicated particles, not falling rain drops.

    You can also leverage the "justborn" group to get particles right when they appear.