Prompt-generated image preview and procedural Houdini HDA output inside Unreal Engine.
Procedural Neon Sign Generator
Type text, pick an image, or describe a prompt → get a 3D neon sign.
I built this procedural neon sign generator for my personal project, Project Yue. It is designed as a production tool for environment signage and set dressing, helping me quickly create editable neon sign assets directly inside Unreal Engine.
The tool supports user-selected image input, direct text input, and optional AI-generated line art through the OpenAI API. It converts the input into procedural neon geometry with tubes, caps, cables, frame, backboard, support structures, automatic color matching, and vertex-color-driven emissive materials.
Key Features
* User-selected image input
* Optional AI-generated input inside Unreal Editor
* Direct text input with selectable font and color
* Automatic image-to-neon color matching
* Procedural tubes, caps, cables, frame, backboard, and supports
* Artist-friendly HDA controls for tube openings, tube thickness, backboard size, material slots, and support placement
* One-click linked HDA rebuild inside UE5
* Dynamic image path output to avoid Houdini texture caching issues
* Optional AI-generated input inside Unreal Editor
* Direct text input with selectable font and color
* Automatic image-to-neon color matching
* Procedural tubes, caps, cables, frame, backboard, and supports
* Artist-friendly HDA controls for tube openings, tube thickness, backboard size, material slots, and support placement
* One-click linked HDA rebuild inside UE5
* Dynamic image path output to avoid Houdini texture caching issues
Technical Notes
The Houdini HDA handles trace processing, curve cleanup, procedural tube generation, backboard creation, cable placement, and color transfer. In Unreal Engine, I built an Editor Utility Widget to generate or select image inputs, preview results, save generated images with prompts, and send the image path directly to the linked HDA.
One key challenge was making the UE-to-Houdini workflow reliable. When generated images reused the same file name, Houdini Engine could read cached texture data instead of the latest image. I solved this by returning a unique dynamic image path from the UE editor node and passing it to the HDA during rebuild.
For color assignment, I tested direct UV-based image sampling and palette-based color matching to transfer source image colors into vertex color. The final UE material uses vertex color to drive emissive neon tube colors.
Built with: Houdini HDA, Unreal Engine 5, Python, OpenAI API.
Houdini HDA node overview: input tracing, color pattern matching, tube generation, cable generation, and three procedural support styles
Dynamic Image Path Output for Houdini HDA Refresh
The custom UE editor node returns a timestamp-based dynamic image path after generation.
This prevents Houdini Engine from reusing cached texture data when the source image is overwritten, ensuring the HDA always reads the latest generated image during rebuild
This prevents Houdini Engine from reusing cached texture data when the source image is overwritten, ensuring the HDA always reads the latest generated image during rebuild
