Setting Up a Snow Generator in Houdini & Unreal Engine 5

Introduction

My name is Robert Baltzer, I'm a 3D Environment Artist who loves real-time art. I am currently looking for work, so most of my work takes place in my own time, although I have worked in VFX as a VAD Artist at Happy Mushroom. Real-time art is what I love to spend my time doing, and I was fortunate enough to use Unreal Engine while being a part of the VFX industry.

I started learning Houdini about two years ago. I've watched tons of videos about the uses of Houdini in games, including GDC talks and YouTube tutorials. It was plain to see the vast potential of Houdini, and I wanted to get the hang of it. But most people are anxious about the software and its daunting complexity. However, there are tons of online information and videos on learning Houdini, and even a few on "how to learn to learn Houdini".

Even when you start up the software, a small Start Here window pops up. If you click on the Learning Paths link, you can see a great number of high-quality videos, sortable by your knowledge level.

The Snow Generator

I started working on the snow generator to test my abilities and out of pure compulsive curiosity. I knew Nanite could handle the dense Geo, so I went away to try. 

The initial network creation process took a day. It worked but it was slow to process and had little functionality. Over the course of a few weeks, I expanded the functionality, while increasing the processing speed by 30 times. I did this by mitigating how often I used expensive nodes and relied more on per-vertex operators rather than processing the geometry as a whole.

Here is my node setup and process:

This tool is meant to take in any Unreal asset and output a snow blanket mesh with an already equipped snow shader. This means it has to be an HDA (Houdini Digital Asset) to be imported into UE5 and used.

Unreal's Houdini Engine plug-in will process this node network and output what we need. The Houdini Engine plug-ins are free to anyone, so that means if you want to use HDAs in most software like this one, you can do so without paying money. However, if you'd like to create HDAs, it will unfortunately cost money.

Here's a great video on how to install Houdini Engine into Unreal:

The generator takes any geometry as the input and uses the normal angles to choose where to place the snow. It can take any mesh and re-mesh it for even topology, necessary for clean displacement. It supports most Megascans assets, however, to use large flat pieces that would be hard to poly fill the open holes, i.e. terrain or embankments, you'll need to close the back. The added thickness will bear more reliable results and faster calculation. This can be done very fast with Unreal's new modeling tools. 

Tips on Learning Houdini

If you're interested in learning Houdini, absolutely do it. But don't jump into a tutorial out of obligation, you won't learn. Make sure to be interested or passionate about the possibilities of learning, and that will assure actual learning.

I used to work as an art software tutor at college, and the one most important thing I noticed while helping educate is if you try to learn something while not interested, you won't learn anything. If you want to retain as much information as possible, you have to study something that interests you or fight to find an aspect of the subject you're studying that is interesting and shows fascinating potential.

A great way to start is by watching videos that display the power and potential of Houdini in use. My favorite video is Sea of Thieves: Tech Art and Shader Development. Videos like this should excite you and get your brain craving for information on what other things are capable of and how these things are possible.  

The first tutorial I would recommend is the Houdini Isn't Scary series, which shows the ins and outs of the software while keeping it simple.

Secondly, I would recommend checking out the Simon Houdini YouTube channel. He has lots of easy-to-follow tutorials and a bunch of great examples of fun uses.

So, look for a positive reason to learn and be excited. Test what you learn after you learn it. And take care of yourself. Don't overburden yourself with unnecessary responsibility. Learn what interests you and go wild. 

Robert Baltzer, 3D Environment Artist

Interview conducted by Arti Burton