Slug Font Rendering Algorithm

Skill by ara.so — Daily 2026 Skills collection.

Slug is a reference implementation of the Slug font rendering algorithm — a GPU-accelerated technique for rendering vector fonts and glyphs at arbitrary scales with high quality anti-aliasing. It works by encoding glyph outlines as lists of quadratic Bézier curves and line segments, then resolving coverage directly in fragment shaders without pre-rasterized textures.

Paper: JCGT 2017 — Slug Algorithm
Blog (updates): A Decade of Slug
License: MIT — Patent dedicated to public domain. Credit required if distributed.

What Slug Does

• Renders TrueType/OpenType glyphs entirely on the GPU
• No texture atlases or pre-rasterization needed
• Scales to any resolution without quality loss
• Anti-aliased coverage computed per-fragment using Bézier math
• Works with any rendering API that supports programmable shaders (D3D11/12, Vulkan, Metal via translation)