Creating a Houdini Tool That Generates Stylized Bridges for Unreal Engine 5

Introduction

Hi! I'm Raimundo Gallino, a Technical Artist from Uruguay. My journey into Tech Art began in traditional 3D art, but I quickly realized that I was more interested in the "how" and "why" behind the scenes, specifically shaders, optimization, procedural workflows, and engine integration.

I'm largely self-taught, fueled by constant R&D and training, such as my time at Vertex School, which helped me bridge the gap between pure art and technical engineering. Regarding my professional background, I have a strong foundation in Unity, which gave me a deep understanding of engine limitations and optimization.

Currently, I'm heavily focused on developing tools for my own narrative horror game in Unreal Engine, which serves as my primary sandbox for testing procedural systems and shader-heavy pipelines. I'm passionate about making complex technical workflows accessible for artists to build faster.

I decided to dive into Houdini a few months ago because I hit a wall with traditional modeling workflows. I needed a way to generate assets that could adapt to any environment without having to manually rebuild them every time. Houdini felt like the missing piece of the puzzle for a more scalable pipeline.

For resources, I've found that the official SideFX documentation is the bible and the joy of VEX CGwiki, but platforms like Vertex School were invaluable for seeing how Houdini integrates into a game engine pipeline. My advice: Don't be intimidated by the Node Graph.

Start by building simple, functional tools (like procedural pipes, staircase, or railing) rather than trying to create an entire city. Understand the "why" behind the attributes, not just the nodes. Once you understand how to manipulate points and normals, you can solve almost anything.

Procedural Bridge Generator

The idea came from a specific production challenge: I was working on a project that required building multiple golf course levels with different layouts, heavily populated by rivers and lakes. Since the environment was constantly changing during iterations, building custom bridges for every single hole was a real pain.

At that time, I knew about Houdini and its potential for level building, but I hadn't yet developed the skills to leverage it. So, I had to endure the process, modeling everything manually with modifiers in Blender. The worst part was that those models weren't "engine-ready". Any changes meant re-exporting and re-adjusting everything.

After I felt more comfortable with Houdini, I decided to retake that challenge with a much better approach. This tool was literally built out of those "lessons learned." I asked myself: "As an artist, what would be the easiest way to set this up in a level?" That mindset led to this curve-based workflow.

Once the procedural foundation was solid, I focused on the stylized direction, drawing heavy inspiration from the latest seasons of Fortnite. I wanted to achieve that clean, vibrant, and readable aesthetic.

Building the HDA

I wanted the controls to be intuitive, so I built the entire system to be driven by a single input curve.

The Column Pattern Logic: The biggest technical hurdle was nailing the specific column rhythm: Big Column -> Small Column -> Small Column -> Big Column. To achieve this, I first used a Resample SOP to discretize the curve into a specific segment count, ensuring that the total number of points was always a multiple of three. Once the curve was properly sampled, I used an Attribute Wrangle to define a modulo-based cycle.

By applying this modulo logic, I could assign a name attribute to each point, flagging them for either "Large" or "Small" columns, which then drives the instancing of the specific custom assets. This combination of resampling and modulo math creates a predictable, repeating rhythm that automatically snaps to any curve length.

Asset Instancing: I designed the HDA so that the user can reference custom static meshes directly in Unreal. This makes the tool artist-friendly: you aren't stuck with my aesthetic. You can swap the columns and railing materials for your own assets while keeping the procedural logic intact.

Also, the HDA exposes key parameters for the bridge layout. Artists can dynamically adjust the bridge width, height, curvature, and plank randomness. These controls add that final layer of organic detail needed to break up repetitive patterns and ensure that each bridge instance feels unique.

Final Renders

For the final presentation, the goal was to showcase the tool in action through a series of environment shots and simple camera animations. In terms of lighting, I used Unreal Engine 5's Lumen to handle real-time global illumination, keeping the setup simple with a directional light for the sun, a skylight for soft shadows, and a few point lights placed to enhance specific details in the scene.

Vertex Data Baking: To keep the shader setup performant, I baked Ambient Occlusion, Cavity, and random color variation directly into the vertex colors inside Houdini. Instead of using expensive real-time calculations, the shader just reads the vertex data. This keeps rendering times low and allows creating these details without heavy calculations in the shader.

Conclusion

The project took approximately three weeks of part-time development from initial concept to the final presentation. The biggest technical challenge was definitely the column pattern logic. As I mentioned before, nailing that specific Big-to-Small column rhythm while keeping the curve procedural and scalable was the hardest part to get right.

I had to ensure the underlying math was robust enough to handle any curve length without breaking the repeating cycle of the bridge. It taught me that procedural tools aren't just about making things faster. They are about creating predictable systems that artists can trust to behave correctly every single time.

Raimundo Gallino, 3D Artist

Interview conducted by Emma Collins