Slug Algorithm (WebGPU)

A WebGPU implementation of the Slug algorithm, originally created by Eric Lengyel.

This project ports the original HLSL shaders to WGSL and demonstrates a modern GPU-driven text rendering pipeline.

Overview

The Slug algorithm renders high-quality vector text entirely on the GPU by converting glyph outlines into a banded Bézier representation.

This repository includes:

• WGSL shader implementations of the Slug algorithm
• A minimal WebGPU rendering setup
• A TypeScript-based shaping pipeline using text-shaper (a HarfBuzz alternative)
• An example using the Inter font

Rendering Pipeline

1. Text shaping (CPU)
   Text is shaped into positioned glyphs using text-shaper.

2. Curve extraction (CPU)
   Glyph outlines are converted into quadratic Bézier curves.

3. Band organization (CPU)
   Curves are partitioned into vertical and horizontal bands.

4. Rendering (GPU)
   The Slug algorithm evaluates the bands and rasterizes glyphs fully on the GPU.

Getting Started

Requirements

• Bun v1.2+
• A WebGPU-compatible browser (e.g. Chrome, Edge)

Install

bun install

Acknowledgements

Huge thanks to Eric Lengyel for creating the Slug algorithm and releasing it into the public domain.

Sources

• https://github.com/EricLengyel/Slug
• https://terathon.com/blog/decade-slug.html