github.com/behdad/glyphy @main

GLyphy is a GPU text renderer that renders glyph outlines directly, using the Slug algorithm by Eric Lengyel for robust winding number calculation.

GLyphy works with quadratic Bezier curves (TrueType outlines) and produces pixel-perfect rendering at any scale with proper antialiasing.

Note: GLyphy is deprecated in favor of the HarfBuzz GPU module, which supports shaders for all major platforms.

Building

Requires: meson, OpenGL 3.3+, FreeType, HarfBuzz, GLUT, GLEW.

meson setup build
meson compile -C build
build/demo/glyphy-demo

How it works

Each glyph's outline is encoded into a compact blob stored in a GPU buffer texture. The fragment shader computes a winding number by casting horizontal and vertical rays against the quadratic Bezier curves, using Lengyel's equivalence class algorithm for numerical robustness. Curves are organized into bands for efficient early exit.

License

GLyphy is licensed under the HarfBuzz Old MIT license. See COPYING for details.