Dynamix Font Format v4-v5

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Dynamix Font Format v4-v5
Dynamix Font v5.png
Format typeFont
Max glyph count255
Minimum glyph size (pixels)0×0
Maximum glyph size (pixels)255×255
Access modeIndexed
Metadata?None
Bitmap glyphs?Yes
Vector glyphs?No
Compressed glyphs?Yes
Hidden data?Yes
Games

The Dynamix v4 font is a 1-bpp indexed font, with the file header specifying the global height for all symbols and the amount of symbols. Like its predecessor, the Dynamix v2/v3 font, it is optimized by only saving the used range of symbols. New features added after v3 include compression support and separate width values for all symbols.

The v5 font is identical, except that it stores 8-bit data instead of 1-bit data. It is distinguished with a different version byte in the header.

Format

The font is embedded in a "FNT" chunk of the typical Dynamix chunk format: a 3-character ID string, followed by a ':', followed by the chunk size in UINT32LE format, in which the highest bit is reserved for a flag indicating whether the chunk embeds chunks inside itself (which this "FNT" one does not), followed by the chunk data. The following descriptions cover the data format inside the FNT chunk, so any offsets are relative to the start of the chunk data, behind this header.

File header

Offset Data type Name Description
0x00 UINT8 Version Version indicator. 0xFF for the one bit per pixel version, 0xFD for the eight bit per pixel version.
0x01 UINT8 FontWidth Maximum width of the font in pixels.
0x02 UINT8 FontHeight Height of the font in pixels.
0x03 UINT8 BaseLine This appears to indicate the Y-offset of the base line of the font. It generally corresponds to the most commonly used lowest pixel Y-position in the symbols, but can be different if the font has a dropped shadow, which is a common feature in v5 fonts.
0x04 UINT8 StartSymbol First symbol code in the font file.
0x05 UINT8 NrOfSymbols Number of symbols in the font file. Since this is a byte, the font is limited to a maximum of only 255 symbols, and not the full 256. However, since C-style strings end with byte 0x00, index 0 is technically useless, and can be skipped to get the full real range.
0x06 UINT16LE SymbolDataSize Size of the (uncompressed) symbol data block.
0x08 UINT8 CompressionMethod ID of the used compression algorithm. See below.
0x09 UINT32LE UncompressedSize Size of the buffer needed to uncompress the data. This should always match SymbolDataSize.

Compression

The following compression types are supported by the format:

  • 0x00: Uncompressed
  • 0x01: Code-based RLE with 1-byte codes. If the highest bit in a code is set, this indicates a Repeat command. The remaining 7 bits specify the amount to copy or repeat.
  • 0x02: LZW. The actual LZW implementation is an adaptive LZW with expanding dictionary size. Decompression code for it is available in a set of MIDI tools released by user tikalat on the VOGONS forum.
  • 0x03: Huffman compression. Decompression code is available in the aforementioned MIDI tools. Note that Huffman was only introduced in later games, so using Huffman-compressed fonts may not work on some earlier games.

Symbol data

This header is followed by the symbol data block, compressed in one of the three known compression methods. After the symbol data is uncompressed, it starts with the offsets and widths data:

Data type Name Description
UINT16LE[NrOfSymbols] offsets Offsets of the data for each symbol, relative to the start of the uncompressed block.
UINT8[NrOfSymbols] widths Width of the individual symbols, in pixels.

Behind this, the font file symbols data can be found, using the offset from offsets, the width from widths, and the global FontHeight. The formula to convert the width to the stride (the actual byte length of a line of pixels) is ((width * BitsPerPixel) + 7) / 8.

Since this data is referenced through an index, the same optimisation technique used in the Westwood Studios v3 font could be applied to it; when multiple symbols have identical image data, the data could be stored only once, and the index positions for these symbols can then point to the same data. This technique is not used by any of the original font files, but the games accept it without issues, since they just follow the references in the index. The Westwood Font Editor allows saving the fonts with this optimisation.

Tools

The following tools are able to work with files in this format.

Name PlatformView images in this format? Convert/export to another file/format? Import from another file/format? Access hidden data? Edit metadata? Notes
Westwood Font Editor WindowsYesYesYesNoN/A Can read the LZW and Huffman compression types, but can't write them.
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