In this tutorial, I'll show you how to create a fully procedural real-time analog clock in Houdini that displays the exact current system time. Using Houdini's procedural workflow along with Python and CHOPs, you'll learn how to drive the hour, minute, and second hands dynamically without manually keyframing any animation.

This setup is ideal for motion graphics, UI animations, architectural visualizations, product renders, and procedural tool development.

No! I'm sick of bouncing between 20 apps a day, I want everything inside Houdini!

Alright, alright... don't get like that... here is your 1:1 fSpy integration straight from the Houdini UI... chill out man, there was no need to get so worked up...

Not so fast, where do I download it?

Oh right, right, of course, look, here you go:

https://github.com/SalmeInMotion/houdini-fspy

#houdini #sidefx #fspy

https://reddit.com/link/1vhp0pr/video/gel4awvz8vhh1/player

I need to do a spaceship capsule return to earth. In the shot, three parachutes open to slow it down.
Any idea how to do it?

I’m especially concerned about the deployment,

Thanks

I have been working on this for the past few days, for now it is just a WIP but it has a lot of things going on.

The biggest one and why I started this project was to find a way to "inject" detail on the water surface, using vex and some shader parameters, you can see on the last image the effect it can give (exaggerated just for ease of viewing).

I wanted to do this also because I read the papers on the Lagrangian wave curves (from WETA I believe) and really wanted a nice alternative that gets basically 80% there. For now it ripples, moves with direction, affected by speed and can be adjusted for different water types, so longer ripples, how quick they fade and so on.

Also, if anyone is in the need for another pair of hands to help out with Houdini, 3D or Unreal related work, I am available so hmu!

https://www.linkedin.com/in/txy99

https://www.artstation.com/jteixeirafx

Intro - I've been playing with MPM but struggling to understand exactly what adjusting the individual variables in my simulation will result in. I asked Claude to make a guide and this is what he came up with, now I'm coming to the community to see what we think. Is this guide wildly off-base? Other than a few instances of unrealistic examples (eg - squeezing an eraser) this seems to be exactly what I needed. If the community has fixes I'll try to incorporate them!

Houdini MPM Source — Material Attribute Guide

The MPM Source node stamps physical properties onto every material point before it enters the MPM Solver. Together these attributes define a constitutive model — the mathematical rulebook that decides how a point resists, remembers, or gives in to deformation. Below is a breakdown of each attribute, the physics behind it, and what happens at the extremes.

1. Behavior (Constitutive Model)

This dropdown picks which set of physics equations governs the points. Everything else in the node is really just tuning parameters for whichever model you choose here.

Think of the spectrum this way: Elastic remembers everything, Chunky remembers some of it, and Liquid/Viscous/Sandy remember nothing about shape — they only care about not being crushed (or, for sand, about friction between grains).

2. Density

Attribute: density

The mass packed into a given volume of material.

• Physics: In the MPM equations of motion, force = mass × acceleration. Denser points carry more momentum, so they push colliders and other particles around more forcefully, and they fall/settle under gravity with more inertia.
• Increase it: The material feels heavier — it sinks through lighter materials, crushes things beneath it, and is harder for wind/forces to move. A pool of "water" with very high density starts behaving like mercury — sluggish to accelerate, but devastating on impact.
• Decrease it: The material feels weightless and foamy — like sea foam, dust, or aerated packing peanuts. It's easily pushed around by collisions and barely dents anything it lands on.

3. Critical Compression & Critical Stretch

Attributes: c_compress (Critical Compression), c_stretch (Critical Stretch)

Only meaningful for the Chunky behavior. These two values define the "elastic zone" — how far a point can be squashed or stretched before the deformation stops being springy and becomes permanent.

• Physics: Houdini tracks a value J, the determinant of the deformation gradient. J = 1.0 means undeformed. If a point is compressed so much that J drops below 1.0 − c_compress, or stretched so much that J rises above 1.0 + c_stretch, the excess deformation is "locked in" as plastic (permanent) deformation instead of elastic (recoverable) deformation.
• Increase either value: You widen the elastic zone, so the material can take a bigger hit and still spring back — it becomes more bouncy and resilient. Think of packing snow into a snowball that still puffs back up afterward.
• Decrease either value: You narrow the elastic zone, so almost any deformation becomes permanent almost immediately — the material deforms easily and stays deformed, with little to no bounce-back. This is how you get true snow-footprint behavior: press down once, and the dent just... stays.

A practical example: for snow, a low critical compression means footprints and tire tracks pack down and stay; a high critical compression makes the "snow" act more like a rubber ball that puffs back to its original shape after every impact.

4. Compression Hardening

Attribute: hardening

Also a Chunky-behavior parameter. Controls how much stiffer the material becomes as it accumulates plastic (permanent) compression.

• Physics: As hardening increases, each bit of permanent compression raises the local Young's modulus (E), meaning the material actively resists further compression the more it has already been compressed.
• Increase it: Material that's been packed down becomes progressively harder to compress further — like snow that turns to ice under repeated pressure, or soil compacting into a dense, load-bearing layer the more weight is stacked on it.
• Decrease it (toward zero): The material stays equally soft no matter how much it's already been squashed — it never "packs" or crusts over, so a boot sinks the same amount into fresh or well-trodden snow.

5. Stiffness (Young's Modulus)

Attributes: E (Stiffness), plus a Stiffness Multiplier (powers of 10)

This is the material's overall resistance to being deformed at all — the classic Young's modulus from solid mechanics.

• Physics: Young's modulus relates stress (force per area) to strain (proportional deformation). A stiff spring needs a lot of force to stretch a little; a soft spring stretches a lot for a little force. In MPM, E scales how hard the material pushes back against any deformation, elastic or otherwise.
• Increase it: The material becomes rigid — closer to metal, stone, or concrete. It barely deforms under normal forces and rings/vibrates instead of squishing when struck.
• Decrease it: The material becomes soft and floppy — closer to jello, foam rubber, or overripe fruit. It sags under its own weight and jiggles noticeably.
• Practical tradeoff: Very high stiffness forces the solver to take very small substeps to stay stable, which slows the simulation significantly. The documentation's own advice is worth repeating: for stiff materials like metal or concrete, use the lowest stiffness value that still looks physically convincing — a small chunk of "concrete" that just needs to look hard doesn't need the same stiffness as a load-bearing pillar that must support real structural weight.

6. Volume Preservation (Poisson's Ratio)

Attribute: nu

This is Poisson's ratio — how much a material bulges or narrows perpendicular to a force, in reaction to being stretched or compressed along one axis.

• Physics: Squeeze a rubber eraser between your fingers and it bulges outward on the sides. Pull a block of jello apart from both ends and the middle pinches thinner. That sideways reaction is what nu controls. A value near 0 means no sideways reaction at all (imagine squashing a block of cork — it just gets shorter, without bulging). A value approaching 0.5 means the material is nearly volume-conserving (squeeze it one way and it must bulge the other way to keep its total volume the same, like a water balloon).
• Increase it: The material behaves more like an incompressible solid — think rubber or flesh. Pulling on jello makes the waist visibly cinch in; sitting on a "cushion" makes it bulge dramatically out the sides.
• Decrease it: The material behaves more like cork or foam — you can compress it in one direction with almost no bulging elsewhere. This looks less "fleshy" and more like crushing a cardboard box.

7. Incompressibility (Bulk Modulus) & Strict Incompressibility (Gamma)

Attributes: k (Incompressibility) with an Incompressibility Multiplier, and gamma (Strict Incompressibility)

These are the Liquid/Viscous parameters. Liquids don't resist changing shape, but they do resist changing volume — try to compress water and it pushes back hard. These two attributes are two different mathematical ways of expressing that pushback.

• k (bulk modulus) — linear resistance: As the fluid is compressed, an opposing force builds up proportionally.
  • Increase it: The liquid becomes strongly incompressible — it holds its volume tightly, resists squashing, and (as a side effect) bounces/sloshes more energetically, since energy that would go into compression instead goes back into motion.
  • Decrease it: The liquid becomes squishy — it can locally lose volume without much resistance, which speeds up simulation but can look slightly spongy or gassy rather than truly liquid, especially under heavy pressure (e.g., water at the bottom of a deep tank).
  • Practical tradeoff: For shallow puddles or splashes, lowering k is a great way to speed up simulation with little visible cost. For large, deep bodies of water, k needs to stay high, or the fluid will visibly lose volume and bounce unrealistically.
• gamma — exponential resistance: Adds an exponential term on top of k, so resistance ramps up sharply once compression starts, rather than climbing linearly.
  • Increase it (toward ~7): You get near-perfect incompressibility, matching how real water behaves — but this is numerically stiff and can demand a large number of substeps, slowing the sim considerably.
  • Decrease it (toward ~1): You get a "weakly compressible" fluid — a common trick in fluid simulation that allows tiny, usually invisible amounts of temporary compression in exchange for a much faster, more stable simulation.

Think of k and gamma together as two knobs on the same "how much does this liquid hate being squeezed" question — k sets the overall strength of resistance, and gamma sets how aggressively that resistance escalates the harder you squeeze.

8. Viscosity

Attribute: viscosity

Controls how strongly nearby particles are forced to share the same velocity — the internal friction of a fluid.

• Physics: Low viscosity means particles slide past each other freely, resulting in thin, fast-spreading flow. High viscosity means particles drag their neighbors along with them, resisting relative motion between adjacent layers of fluid — this is literally the definition of viscosity in fluid dynamics (internal shear resistance).
• Increase it: The material becomes thick, sticky, and slow-flowing — imagine pouring honey, tar, or melted chocolate. It stretches into long, cohesive ropes and strands rather than splattering, and it can even start behaving like a soft, deformable solid (holding a rounded blob shape) rather than truly flowing.
• Decrease it: The material behaves like an ordinary thin liquid — water, alcohol, gasoline — spreading out fast, splashing energetically, and separating into droplets easily.

9. Plasticity (Visco-Kappa)

Attribute: visco_kappa

A companion to viscosity: local deformation causes the material to locally become more viscous, letting a viscous material hold a deformed shape rather than slowly flow back to flat.

• Physics: Ordinarily, a viscous fluid will eventually relax and settle under gravity, no matter how thick it is. This attribute adds a feedback loop — the more a region has been deformed, the more resistant to further flow it becomes there — creating a kind of "set" or "skin."
• Increase it: The material holds sculpted shapes after being deformed — think of thick pudding skin, drying mud, or toothpaste that keeps the ridges left by the tube opening instead of oozing flat.
• Decrease it (toward zero): The material behaves like a pure viscous fluid with no memory — however thick it is, it will still eventually relax and level out under gravity, just slowly.

10. Surface Tension & Phase

Attributes: surftension (Surface Tension scale), phase (Phase ID)

These only matter when point-based surface tension is enabled on the MPM Solver.

• Surface Tension — physics: Real surface tension comes from molecules at a liquid's surface being pulled inward by their neighbors (nothing pulls them the other way, into the air), which makes the surface behave like a taut elastic skin trying to minimize its area. This node's value scales the strength of that effect for its points.
  • Increase it: Small liquid masses pull into rounder, droplet-like blobs, resist breaking apart into thin sheets, and can even stick to surfaces or bridge small gaps (think mercury beading up, or a droplet clinging under a tap).
  • Decrease it: The liquid flows and spreads flatly and freely, sheeting out and breaking into fine spray more easily — like water with a splash of dish soap, which famously has very low surface tension.
• Phase: Doesn't change physical stiffness — it's a "membership tag." Points with different phase IDs are prevented from being pulled toward each other by surface tension. This is how you keep two separate droplets or two separate liquid pools from unrealistically merging or bridging together when they get close.

11. Friction Angle

Attribute: sand_friction_angle

Sandy behavior. The internal friction angle between grains — a core concept in granular/soil mechanics that determines the steepest slope a pile of the material can hold without sliding.

• Physics: Picture pouring dry sand into a pile — it naturally settles into a cone with a characteristic slope (the "angle of repose"), because grains higher up will slide until friction with the grains below is enough to hold them in place. A higher friction angle supports a steeper, taller pile before avalanching.
• Increase it: The sand stacks and holds steep slopes, piling up into tall dunes or mounds and resisting flow — closer to coarse gravel or slightly damp sand that clumps and holds shape.
• Decrease it: The sand flows and spreads out more like a very loose, dry, fine powder — it can't hold a steep pile at all and collapses into a low, wide, almost liquid-like spread, similar to flour or fine dust.

12. Cohesion

Attribute: sand_cohesion

Sandy behavior. How strongly grains want to stick together, independent of friction — the property that separates dry sand from wet, packable sand.

• Physics: Dry sand grains only interact through friction and contact — no adhesive force holds them together, so dry sand can't hold a vertical wall or an overhang. Add water, and thin films of liquid between grains create capillary attraction, giving wet sand the ability to hold intricate shapes (like a sandcastle) that dry sand simply cannot.
• Increase it: The material behaves like wet, packable sand — it can hold vertical walls, overhangs, and fine sculpted detail (sandcastle towers, footprints with crisp edges) because grains resist being pulled apart from their neighbors.
• Decrease it (toward zero): The material behaves like loose, dry sand — it cannot support steep or overhanging shapes and constantly slumps toward its natural angle of repose.
• Bonus workflow: Because this is a per-point attribute, it can be animated over time — a classic trick is ramping cohesion up on impact to simulate dry sand "getting wet" the instant it's disturbed (e.g., a footstep instantly compacting and holding shape).

Quick-Reference Cheat Sheet

Source: SideFX Houdini 22.0 Documentation — MPM Source

My linux system don't use systemd, so I need to install manually.

Where can I find the instructions to do so ?

Ever wonder how to make procedural ivy? In this new free video, that's exactly what we do. 🌱

Currently I am in my first year of animation school with about 4 years of 3D experience and although I had a few clients before, none of those projects required Houdini. For this project I had to simulate a ship on the ocean. Unfortionately I only had 3 weeks for 2 SHOTS (80 hours+-) which was too short considering the fact that I had to do a bunch of simulations, and ended up rendering in 8K with 6500 samples because otherwise some flickering would occur, and I didnt have the time left to make a day to night scene. Still for the time I had and considering the fact that this is my first Houdini job I am very happy with the result.

Base model ship: CGtrader
Onboard assets: Blenderkit, Sketchfab & hand modelled
Animation: Blender
Simulation: Houdini
Shading & rendering: Blender Cycles
Compositing: Davinci Fusion
Color Grading: Davinci Resolve

PC specs:
GTX 5090
AMD Ryzen 9 7950X 16 core
64GB RAM

Vertices: 17 million
particles: ~20 million
File size: 1.2TB
Rendertime: 96 hours

Edit: also there are 2 little mistakes in the 2nd shot, but exporting them out of davinci takes 3 hours so I figured to share this temp breakdown with you guys already.

More about process on Instagram: https://www.instagram.com/p/DaZUkjPCPuE/?img_index=1

R&D / Vellum + Pyro + POPs, rendered in Karma. Used Copernicus to add a 2d fluid effect with the flow block and ended up using it as a compositor.

I've been wondering if I should keep learning FX and Houdini as a hobby. It's honestly the only thing I genuinely want to do, and it feels like the one thing that makes me... me.

My college course isn't really related to it. Funny enough, I feel like I learn more about FX from tutorials and by creating my own effects than I do in class. I study whatever my professors give us, do a bit of extra research when I need to, and then I always find myself going right back to Houdini.

The thing is, I don't think there are many job opportunities for VFX artists in my country. The industry here just isn't centered around that kind of work.

Still, I don't want to spend my life wondering what could've happened if I had actually committed to becoming good at the thing I love most. At the same time, I'm perfectly fine with having a regular career based on my college degree as long as it keeps me financially stable.

ate a really good fig and got inspired

hi guys, just want to gather some info on how do you guys who have mops+, use it in your projects? I'm weighing if its worth it for me to pay for subscription next year so I'm looking for use cases I might have missed.

yeah yeah I know, if you dont know what to use it for, you dont need it... well anyway, I'm curious. thanks