Difference between revisions of "Background/Arena File Format (.BK)"
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!colspan=2| Desert [4 palettes] | !colspan=2| Desert [4 palettes] | ||
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| 5-18 || Slow fade to white | | 5-18 || Slow fade to white | ||
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Revision as of 22:29, 24 November 2009
The BK file format is similar in many ways to the AF file format, however, there are some signifigant differences.
Header
| Unknown | 1 DWORD | 0 for INTRO, 2 for ending cutscenes,4 for main menu/newsroom/VS/Mechlab/melee, 6 for credits,
8 for Arena0, 16 for Arena1, 32 for Arena2, 64 for Arena3 and 128 for Arena4 |
| Unknown | 1 BYTE | ? 1, 2 or variable |
| Width | 1 WORD | Background width (always 320?) |
| Height | 1 WORD | Background height (always 200?) |
Animations
Each animation is preceded by the offset of the next animation stored as a DWORD, along with an animation number. Reading the animation and advancing the file pointer should result in the file pointer being the same as the next animation offset. An animation number >= 50 marks the end of the animations section. When this occurs, the next animation offset is set to the offset of the current animation.
| Next animation | 1 DWORD | Position of next animation relative to start of file, in bytes |
| Animation number | 1 BYTE | Unique identifier for animation |
Animation Header
| Unknown | 1 BYTE | Nul padding? |
| Unknown | 1 BYTE | |
| Unknown | 1 BYTE | |
| Unknown | 1 BYTE | |
| Unknown | 1 WORD | |
| Unknown | 1 BYTE | |
| Something size | 1 WORD | |
| Something | N BYTES | Size is determined by the previous value |
There then follows an animation structure (see .AF file format).
After the animations there is a footer structure:
| Background image | W*H BYTES | W and H are the width and height in the file header |
| Num palettes | 1 BYTE | Specifies the number of palettes which follow |
Palettes
| Palette data | 256 * 3 BYTES | A palette |
| Palette remapping tables | 19 * 256 BYTES | See below |
The palette remapping tables are maps from image colour indices into palette indices, for various different colour effects. The tables are for:
| Index | Purpose |
|---|---|
| 0-3 | Fade to black, for shadows |
| 4 | Dark blue, for menu backgrounds |
| Most BK files | |
| 5-8 | Saturating to white, then black-and-white (newsroom transition?) |
| 9-13 | Saturating light blue -> white (lightning flashes?) |
| 14-18 | Green (?) |
| Fire pit [3 palettes: normal, fire, ice] | |
| ?? | TODO |
| Desert [4 palettes] | |
| 5-18 | Slow fade to white |
| Unknown | 30 BYTES |