r/Houdini

The idea originally came from an R&D task I was working on for a client project earlier this year. I liked the underlying behavior enough to revisit it later and push the technique further as a personal experiment.

I first created an initial simulation focused on the main velocity field, while also generating UVs internally as an additional 2D Pyro field. That first sim then became the advection driver for the bubbles and their velocity, allowing them to inherit the motion and flow of the fluid in a more natural way.

After that, I created a second fluid simulation using only the velocity from the first Pyro setup, combined with collisions and bubble velocity. This made the fluid react to spheres moving across its surface, changing the internal mixing and creating more dynamic interaction.

I also experimented with a non-divergent workflow in COPs, but for this particular look it was missing some of the organic, naturally unstable motion that I still get from the old 2D Pyro Solver.

A fun experiment in using Pyro not only as smoke, but as a flexible field-based solver for art-directable fluid motion and procedural detail.

Since Houdini 22 was released I have been building a set of GPU enabled particle tools that work directly in COPs. Here are some renders showing just a bit of what they can do.

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I recently found the published FlyWire fly brain dataset and thought it would be really interesting to bring it into Houdini.

I imported the neuron skeletons as curves and combined them with the published annotation data, which gave me a lot of useful information to visualize.

From that data I could create different color visualizations based on actual brain information, like brain groups, Kenyon cells associated with learning & memory and the two sides of the brain.

I could probably make 1000 more renders of this, but here are my 3 favorites!

See the video and more renders on my Instagram:

https://u2l.ai/bramgunst-instagram

Data credit - FlyWire / Schlegel et al.:

https://doi.org/10.5281/zenodo.10877326

I'm experiencing this weird issue. It's true it's a very large-scale simulation, but, for example, in the top cam, it seems to be right, but not in my cams or perspective viewport. Does someone know what's happening?

A few years ago, I came across the amazing Mimic effect by Cartesian Caramel and kept trying to recreate and improve the technique over time. His original version was made in Blender; this is my take on the idea, built entirely in Houdini.

I added a few new behaviors:

The Mimic avoids placing its legs in areas it can't see.

Each leg can move at a different speed, creating more varied and unpredictable motion.

At the end of the video, you can see a comparison of my progress and how the effect has evolved over the years.

Made a web site and a shelf tool that allows you to share Houdini node setups via copy and paste.

We just revamped the look. Hopefully it is a bit cleaner and easier to use!

https://codercat.xyz/cookbook/

I want to model buildings like this procedurally.

How do I approach this? What skills do i need?

Any videos on yt would be appreciated.

I am still a beginner in houdini, using apprentice ver.

I'm currently working through a scene from Nick Medukha where a sphere hovers over the white discs and they simulate bouncing around and as the sphere travels further, the disc settle back into their rest state.

The scene is basic for the most part and is composed of about 50,000 points. Not super light, but feels relatively low. When I file cache and load from disk, I'm not even getting half the real-time playback speed when I'm pulling from my local drive. Even if I were to delete all the attributes before caching, I still can't get real-time playback on the full-geometry unless I'm viewing through a point cloud or similar super lower res quality. Turning the viewport into wireframe mode is not improving the playback neither.

Just to note, I am working on a Mac and I know it can be slower than PC. Even on PC I've feel like I have run into these types of issues before. Is there some best practices I'm missing rather than exporting to flip-book every time to see previews playback well in the viewport?

Thanks for your help!

Having fun with Copernicus 💪

Hi, i am trying to follow a tutorial on vellum snow simulation, and while trying it i noticed that my same setup in h22 and h21 gave completely different result,
and this happened only once on the h21, when trying again without changing anything on h21 i got same result as h22.
in the video - left side is h22 and right is h21 with the result i am looking for.

in h21 i am getting all the clumping to the snow but not, even if it only happened once is there any other way as well to get the similar results?

Hi Guys,

do you also struggling with understanding APEX? Trying to get into since release but usually drop it and use KineFX for projects.

I know there are good tuts out there. But during last three years I am facing several problems.

-There are a lot of changes in each version. (so at one point tuts are useless)

-It is really different than ususal houdini ux

Any advise how to get on the APEX ride.

Personal work. Copy to points workflow for the figures. Each part gets a template point with various transforms applied to it. Maybe easier with a proper crowd setup, but this was quite fun to figure out the looping and various elements characters.

In this focused RnD, I implemented a small-scale fluid simulation algorithm within Flip to accurately resolve adhesion forces. The core algorithm is relatively straightforward: the fluid's surface field is extrapolated into the collider volume, factoring in the contact angle, and is subsequently adjusted and smoothed. Furthermore, a localized viscosity is introduced at the fluid-collider interface to approximate boundary friction.

The simulation operates at a physically accurate real-world scale, utilizing empirical physical constants where the baseline water viscosity is 0.001 and surface tension is 0.072. APIC was chosen as the underlying solver.

While this technique requires a high substep count and is computationally expensive to evaluate, it successfully produces highly nuanced and realistic fluid dynamics.

Hey everyone,

I'm not a Houdini user myself, but after seeing how my wife struggles with editing Python code in Houdini I've built a little code editor in form of a plugin. It has built-in linter to highlight syntax errors and can run the code right away (force-cooking the node before that), the execution errors and log messages (like the print() method) are displayed in the built-in console window. Everything is in there, you don't have to switch to Python Shell to see errors and print() outputs.

I'm not a Houdini user myself, so I'd appreciate your feedback on the plugin. Feel free to give it a try, it's available for Windows, Linux and MacOS (although I only tested on my Mac so far).

You can download the plugin from Github: https://github.com/yurist38/mad-coder-houdini-plugin/releases . Installation is pretty straightforward, you can find instructions in the README file in the repository or inside the downloaded archive.

Looking forward to hearing back from Houdini experts!

Hi! I'm trying to recreate the FLIP simulation from this reference:

https://www.instagram.com/p/Db_WFG3kbhM/?img_index=2

I'm especially trying to reproduce the way the black liquid folds and overlaps onto itself, creating those small visible layers/ridges (image 2).

My current result is shown in image 1. The general motion is getting close, but my fluid stays extremely smooth and basically turns into one continuous sheet/blob instead of creating those overlapping folds.

Current setup:

• Viscosity: 400
• Surface Tension: 5
• Swirly Kernel
• The emitter is animated from right to left across the cylinders.

I'm wondering what I'm missing to get that layered/folding behavior. Is it mainly related to viscosity, emitter speed, particle separation, surface tension, or something else in the FLIP Solver?

Any advice on how to achieve the viscous buckling/folding visible in the reference would be really appreciated!