Kingdom Hearts Birth By Sleep - Font archive
At the path arc/system/, the two files font.arc (Japanese font) and fonten.arc (European font) can be found. Those files are nothing more than an archive with all the information needed to render a character or a font image.
Font types
The following font types can be found in both font archives:
cmdfont, used for the command HUD at the bottom left.helpfont,menufont, used inside the menu.mesfont, used for game dialogs. This is the most complete font.numeral, it just contains numbers between 0 and 9.fonticon, stores console button and game icons.
Character mapping
Internally, the game engine uses UCS as encoding, meaning that all the Shift-JIS text is ingested and converted on-the-fly to 2-bytes for each character. Then it does a look-up to both INF for FontIcon and COD to match and print that specific character by searching it using the Character ID.
Embedded in the executable, a hard-coded switch table is responsible to convert the characters from 0x21 ('!') to 0x7E (~) into a UCS character.
INF
Describes the texture of a font.
| Offset | Type | Description |
|---|---|---|
| 00 | short | How many characters the texture contains. |
| 02 | short | Texture width. |
| 04 | short | Texture height. |
| 06 | byte | Character width. |
| 07 | byte | Character height. |
INF - FontIcon variant
For fonticon, the associated INF file is structured in a completely different way.
| Offset | Type | Description |
|---|---|---|
| 00 | short | Character ID |
| 02 | byte | Left |
| 03 | byte | Top |
| 04 | byte | Right |
| 05 | byte | Bottom |
| 06 | short | Always 0 |
Left, Top, Right and Bottom are used to locate the icon in the texture
MTX
A 4-bit image (8-bit for fonticon) that stores all the characters in a grid. The texture is swizzled by 256 bytes, which means that the content is stored by 32x16 pixel blocks at the time (16x16 for fonticon since it is in 8-bit).
The texture size will be smaller than width * height * bpp / 8 bytes long since it is swizzled. That means that the image content at the bottom-right does not contain any data since the 32x16 pixel blocks are not needed to be stored.
Since the colors of each pixel is indexed, a color look-up table is provided.
CLU
A 1024 bytes long file that stores one or more palettes for a given MTX.
For 4-bit MTXs, this file will contain up to 4 different palettes of 16 colors, but is most likely that only the first two are actually used.
For font files, switching between palette 1 and palette 2 will reveal two different contents from the same bitmap, a technique used in Kingdom Hearts II font files too.
For 8-bit MTXs, the file will be considered as a single palette of 256 colors.
The palette format is RGBA (bytes are stored as 0xRR 0xGG 0xBB 0xAA).
COD
Provides the necessary info to print a given character.
| Offset | Type | Description |
|---|---|---|
| 00 | short | Character ID. |
| 02 | short | Position X. |
| 04 | short | Position Y. |
| 06 | byte | Palette index. |
| 07 | byte | Actual character width. |
The Character ID is not necessarly unique, for some weird reason. It is used to associate a specific font’s texture area to a given Shift-JIS character.