BFF File Format
CBFG native output for font files is Bitmap Font File (BFF) format.
The format supports 8, 24 and 32 bit fontmaps up to 4096x4096 pixels and specifies character width and positioning information.
The files start with a 20 byte header:
| Offset | Size (Bytes) | Description |
|---|---|---|
| 0 | 2 | ID - 0xBF 0xF2 (BFF Version 2) |
| 2 | 4 | Font Image width |
| 6 | 4 | Font Image height |
| 10 | 4 | Cell width |
| 14 | 4 | Cell height |
| 18 | 1 | BPP - will be 8, 24 or 32 |
| 19 | 1 | Base character offset - This is the ACSII value of the first character on the font map. |
| 20 | 256 | Character widths |
| 276 | Variable | Image map data |
Rendering Text using BFF fonts
To render a specific character from the font follow this example pseudocode:
Calculate the number of characters per row on the texture. (Integer value)
RowPitch = ImageWidth / CellWidth
Calculate the row and column of the glyph within the texture. (Integer values)
Row = ( CharASCIIValue - BaseCharOffset ) / RowPitch Col = ( CharASCIIValue - BaseCharOffset ) - ( Row * RowPitch )
Calculate the UV dimensions for a cell. (Floating point values)
ColFactor = CellWidth / ImageWidth RowFactor = CellHeight / ImageHeight
Multiply the row and column values by the UV factors to obtain the UV coords of the top left of the character.
U = Col * ColFactor V = Row * RowFactor
Add the UV factors to the UV coords to find the bottom right of the character.
U1 = U + ColFactor V1 = V + ColFactor
Render the glyph using the cell height and width values as polygon dimensions, apply the texture using the calculated UVs.
Use the character's ASCII value as an index into the array of width values to determine the spacing required to place the next glyph.