Animations
Table of Contents
A file with the J2A extension is a Jazz Jackrabbit 2 Animation Library, copyrighted by Epic Megagames.
Analysed by Dr. Eggman of Jazz2Online.
Technicals
J2A Header
Header of animation library contains:
| Offset | Data and meaning |
|---|---|
| 0000 | 1st identifier: ALIB |
| 0004 | 2nd, hexadecimal identifier: 00 BA BE 00 |
| 0008 | probably a pointer to the files table |
| 000C | unknown dword value |
| 0010 | j2a file size |
| 0014 | another unknown dword value |
| 0018 | number of ANIM chunks (ZLIB-compressed) inside the library |
At offset 001C there are pointers to ANIM chunks, size of the table is (number of ANIM chunks)*4 bytes.
ANIM chunk Header and structure
JJ2 animation library is a pack of ZLIB-compressed files, called ANIM chunks.
| Offset* | Data and meaning |
|---|---|
| 0000 | 1st identifier: ANIM |
| 0004 | two unknown dword values |
| 000C | 1st anim file compressed data size |
| 0010 | 1st anim file original data size |
| 0014 | 2nd anim file compressed data size |
| 0018 | 2nd anim file original data size |
| 001C | 3rd anim file compressed data size |
| 0020 | 3rd anim file original data size |
| 0024 | 4th anim file compressed data size |
| 0028 | 4th anim file original data size |
* – Keep in mind that is a relative offset.
At offset 002C there are the anim files put in order.
Each ANIM chunk, after decompression of the four files contains (in ANIM header order):
animXY 0: a number of animation images and some other yet unknown data
animXY 1: the animation sequences information with animXY 2 pointers and so on
animXY 2: graphics and some yet unknown data
animXY 3: (if exists) identified sound effects that belongs to animation sequence
XY is an ID of extracted animation info file, 0 - 3 is an identifier of data type it has (my custom file naming concept).
Please note that: information about some values and how images are stored is not yet fully analysed. More data will be added soon…
Dr. Eggman