Sonic Jam/Textures
From Sonic Retro
| SCHG: Sonic Jam |
|---|
| Main Article |
| Sonic World |
Texture Definitions
Texture Definitions start at $250A4 in MUSEUM.MUS.
These are basically a set of data, each 8 bytes long, that defines a texture. Here's its format:
| Description | Size |
|---|---|
| VDP1 Address / 8 | word |
| Width / 8 | byte |
| Height | byte |
| Palette Lookup Table Address / 8 | word |
| VDP1 Address / 8 (again?) | word |
Texture Patterns
Texture Pattern Data starts at $1AFC0 in SPRDATA.MUS.
Texture patterns are a string of data, wherein every 4 bits is one pixel. This of course means that you are limited to the 16 colors defined in this texture's color lookup table. The value of the 4 bits determines which color is used, with a value of $0 meaning the first color in the table is used, and a value of $F meaning the last color in the table is used.
The Saturn is capable of having different pattern modes; There's an 8 bits per-pixel mode, and a 16 bits per-pixel mode; It's yet to be confirmed if any of these textures use that.
Color Lookup Tables
Color Lookup Table Data starts at $0AFC0 in SPRDATA.MUS.
Each table is 32 bytes. Every word defines a single color.
This part needs some serious work; I'm not very sure about how this stuff works yet.
If bit $8000 is set, the color seems to be defined in RGB mode. Bits $4000-$0400 are blue, bits $0200-20 are green, and bits $10-$1 are red.
If bit $8000 is not set, then something else seems to happen.