gsfnt 0.1.1

Pack a folder of images into BMFont (.fnt) and a merged PNG atlas
gsfnt-0.1.1 is not a library.

gsfnt

CLI tool that packs all images in a directory into a BMFont text .fnt file plus a single merged RGBA PNG atlas. Each glyph’s Unicode code point is taken from the first character of the image filename stem (the part before the extension).

Install

cargo install gsfnt

Or build from this repository:

cargo build --release
# binary: target/release/gsfnt

Usage

gsfnt --input /path/to/images --output /path/to/out/font

This writes:

  • font.fnt — AngelCode-style BMFont (text format)
  • font.png — atlas image referenced by the .fnt

If --output already ends with .fnt, that path is used as-is and the PNG is the same path with .png.

Options

Option Description
-i, --input Directory containing source images
-o, --output Output prefix (see above)
--max-width Maximum row width for shelf packing (default: 4096)

Supported image extensions

png, jpg, jpeg, webp, gif, bmp

Filename → glyph

  • A.png → glyph for A (U+0041)
  • 中.png → glyph for 中
  • emoji_rest.png → glyph for the first character only (e)

Duplicate code points (two files mapping to the same first character) are rejected with an error listing both paths.

Font metrics (output)

  • lineHeight / base = maximum image height among all glyphs
  • xoffset = 0
  • yoffset = lineHeight - height (bottom-aligned within the line box)
  • xadvance = glyph width

License

MIT. See LICENSE.