The Sprites File Format¶
Introduction¶
Sprites are an important technology in game development. Since the Amiga sprite hardware expects sprite data in a specific format it is useful to arrange sprite sheet data in a format that requires no or just minimal processing after it is loaded. Therefore the RATR0 utilities generate a separate file format for Amiga sprites to help with this. In contrast to the tiles format the sprite format is specifically tailored to Amiga sprites.
Specification¶
Header¶
Byte number(s) |
Name |
Description |
|---|---|---|
0-7 |
ID |
Always |
8 |
version |
file format version |
9 |
flags |
bit 0: not set -> big endian, set -> little endian
|
10 |
reserved1 |
reserved byte, currently only used as padding |
11 |
palette_size |
number of palette entries |
12-13 |
num_sprites |
number of sprites in the file |
14-17 |
imgdata_size |
size of image data in bytes |
18-19 |
checksum |
checksum of the file (currently unused) |
Sprite Offset Data¶
Following the file header are num_sprites 16 bit words of offset numbers which
represent the byte offsets where each sprite’s data structure starts.
Palette Data¶
Following the sprite offset data is a block consisting of the palette entries.
These are palette_size 16 bit words containing the RGB values of each entry.
Typically only the least significant 12 bits will be valid.
Sprite Data¶
Immediately following the palette data is the sprite data. The data is in the same format as the Amiga sprite structure: The first 2 words will contain the sprite’s height,
Word number(s) |
Description |
|---|---|
0 |
Height of the Sprite |
1 |
contains a set attachment bit if more than 4 colors |
2- |
height * 2 words of actual sprite image data |
last 2 words |
always 0 to denote the end of the sprite structure |
