Houdini oil in water

There are many ways to move millions of points in Houdini. Usually, quicker one is to make static velocity fields and move all points through it. But my approach is to make fields with Pyro, which also driven by particles, to have more control over how fluids are moving. Then move all the points through Pyro velocities, with possible mixing with other sources.

Let’s take a look at a first example.

1. Simple particle setup making a swirl.

2. Previously made points are passed to Pyro for more interesting liquids dynamics. In this case, I used a 2d fluid grid which works much quicker.

3. Velocities from Pyro advected big count of points.

Wedge Simulations

Wedge in Houdini is like partitions in Krakatoa. It allows splitting particles saving into smaller chunks, which greatly reduce simming time. In my case wedge changes only particles seed, so setup is simplified as possible.

To make full quality renders like in the examples. Just go to ropnet1_simming and run wedge1. After that load all partitions in 4_RENDER_PRTCL_CACHES and you’re ready to render the final image sequence with ropnet2_render.


Check out more HIP files at Gumroad.

    1. Maybe you have older Houdini version? I made this with 16.5.323, but should work in newer versions as well.

  1. Man, that is awesome, thanks a lot. Houdini is a monster of a software! One question though one round of wedge took almost 40 Gigs of HD.
    Your example is set to 20 times that – almost a TB of disk space – is that right or am I doing something wrong.

    Anyway – your content is fanstastic! Keep it up.

  2. Awesome stuff, man! Keep it up.
    One round of wedge took around 40 GB of space – is that correct? Seems that all 20 wedges will take almost 1 TB of space, kinda heavy.

    1. That’s correct. Wedges count isn’t required to have so many, you can have a pretty decent result with less.
      Also, file sizes depend on which data you’re saving. If you don’t need velocity or age/lifespan, you can easily remove them from saving. In my situation, I leave them to have more coloring ability after caching.

  3. This looks amazing. I’d love to render but keep getting the following error when trying to render wedge1:
    „Cannot find channel ../../obj/particles/popnet/source_first_input/seed”.
    I use Houdini 17 (and I’m sorry if I oversee something trivial)

    1. It seems object name was changed. Point it to the actual object in your scene – ../obj/3_particles/…

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