Font Files

Working with .fnt font bitmap files in DOKAPON! Sword of Fury.

Table of Contents

  1. Overview
  2. Known Font Files
  3. File Format
    1. Structure
    2. LZ77 Compression
    3. PNG Detection
  4. Extracting Font Bitmaps
    1. Using the Asset Extractor
  5. Modifying Font Bitmaps
    1. Manual Reimport Process
  6. Common Modding Use Cases
    1. Font Translation
    2. Visual Font Reskin
  7. Troubleshooting
  8. Technical Reference
  9. Contributing
  10. License

Overview

The game stores its font bitmaps in a proprietary .fnt format. Each .fnt file contains a PNG bitmap sheet of glyphs, optionally preceded by an LZ77-compressed header. The primary tool for working with .fnt files is the Asset Extractor — its Fonts tab lists every font file in the game and can preview and extract the embedded PNG.

This page documents the .fnt format itself and describes how to interpret font files for modding purposes.

Known Font Files

The base game ships one primary font file:

FileLocationPurpose
Quarter.fntGameData/app/Font/Quarter.fntMain game font (all in-game text rendering)

Additional .fnt files may appear in language-specific subdirectories depending on the game version.

File Format

Structure

[Optional LZ77 header]     -- if the file starts with "LZ77" magic bytes
[PNG data]                 -- standard PNG with signature 89 50 4E 47 0D 0A 1A 0A
[Optional trailing data]   -- game-specific metadata, can be ignored for image extraction

The PNG component is a grayscale or RGBA bitmap sheet containing all glyph characters used by the game’s text renderer. Each glyph occupies a fixed cell on the sheet, which the renderer references by character code offset.

LZ77 Compression

Some .fnt files are compressed with the game’s Nintendo-style LZ77 variant. If the first four bytes of the file are 4C 5A 37 37 (LZ77 in ASCII), the file must be decompressed before the PNG can be read.

The Asset Extractor handles this transparently — selecting a compressed .fnt in the Fonts tab will still show the decompressed PNG in the preview panel.

See LZ77 Compression for the full format specification.

PNG Detection

The embedded PNG is located by scanning for the standard 8-byte PNG signature:

89 50 4E 47 0D 0A 1A 0A

The PNG data runs from this signature to the end of the IEND chunk (49 45 4E 44 AE 42 60 82).

Extracting Font Bitmaps

Using the Asset Extractor

  1. Open DokaponSoFTools.App.exe.
  2. Navigate to Asset Extractor in the left panel.
  3. Switch to the Fonts tab.
  4. Click any .fnt file to see the glyph sheet in the preview panel.
  5. Set an output directory and click Extract All to save the PNG to disk.

The extracted PNG is the raw glyph sheet, ready to be edited in any image editor that supports PNG (Photoshop, GIMP, Aseprite, etc.).

Modifying Font Bitmaps

Reimporting a modified font PNG back into a .fnt file requires manually replacing the embedded PNG bytes at the correct offset. There is no automated reimport for font files in the current version of the toolkit.

Manual Reimport Process

  1. Note the byte offset of the PNG signature within the original .fnt file (available from any hex editor).
  2. Prepare your modified PNG — it must be identical in dimensions and colour format to the original. Changing the image dimensions will break the game’s glyph indexing.
  3. Open the .fnt file in a hex editor.
  4. Replace the bytes from the PNG signature to the IEND chunk with your new PNG data.
  5. If the new PNG is smaller than the original, null-pad the remaining bytes to preserve file size.
  6. If the new PNG is larger, the file size will grow — this may or may not be compatible depending on whether the game loads the file by absolute size.

Automated font reimport is planned for a future version of the toolkit. Check the GitHub repository for updates.

Common Modding Use Cases

Font Translation

To translate the game into a language with a different character set (e.g. adding Latin Extended glyphs, or replacing CJK glyphs with a custom Latin font):

  1. Extract the glyph sheet PNG from Quarter.fnt.
  2. Identify the glyph layout — which cell corresponds to which character code.
  3. Redraw or replace glyphs in the appropriate cells.
  4. Reimport the PNG back into the .fnt file using the manual process above.

Visual Font Reskin

To change the visual style of the game’s text (e.g. making it bolder, adding an outline, or changing the colour):

  1. Extract the glyph sheet.
  2. Apply your desired visual treatment in an image editor, keeping glyph positions identical.
  3. Reimport using the manual process.

Troubleshooting

Fonts tab shows no files Confirm that your game directory is set and that GameData/app/Font/ exists within it.

Preview shows nothing The .fnt file may be compressed and decompression may have failed, or the file may not contain a standard PNG. Check the status log for error messages.

Extracted PNG appears all white or all black This is normal for some glyph sheets — the visible glyphs are rendered using the alpha channel. Open the extracted PNG in an editor and examine the alpha channel separately.

Technical Reference

For more on the compression format used in font files, see LZ77 Compression.

Contributing

Found a bug or want to suggest an improvement? Open an issue on GitHub or join the Discord.

License

This tool is part of DokaponSoFTools, released under The Unlicense (public domain). See the LICENSE file for full details.