Gods Path Format
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Some enemies in Gods fly along fixed, pre-recorded paths instead of reacting to the player. These paths are stored in PGOD0n.PAT, one file per world (n = 1-4). The files are compressed with PKWARE DCL Compression. Despite the extension they have nothing to do with instrument patches: "PAT" is short for path.
The file is loaded when sublevel A of a world starts and is used for both sublevels. Path enemies are started by event type 1 in the Gods Level Data Format, whose spawner record gives the path number, the number of enemies and the delay between them.
File format
The file is a directory of 50 entries followed by the path data.
Directory
50 entries of 8 bytes (400 bytes in total).
| Data type | Name | Description |
|---|---|---|
| UINT32BE | offset | Offset left over from the Bitmap Brothers' tools, never used by the game. 0xFFFFFFFF marks an unused entry. (The game overwrites the first word with a memory pointer at load time.) |
| UINT16BE | unused | 0 or 0xFFFF |
| UINT16BE | length | Length of this path's data in bytes |
The path data is stored in order straight after the directory, so path i starts at 400 + (sum of the lengths of all earlier entries). Unused entries (first word 0xFFFF) are skipped and take no space. Entries with a length of 0 are also empty. The file size is always 400 + (sum of all lengths).
| File | Used paths | Size |
|---|---|---|
| PGOD01.PAT | 38 | 5320 |
| PGOD02.PAT | 6 | 776 |
| PGOD03.PAT | 1 | 556 |
| PGOD04.PAT | 22 | 2818 |
Path data
A path starts with its starting position, in one of two forms:
| Form | Header | Meaning |
|---|---|---|
| Absolute | The bytes 23 45, then UINT16BE x, UINT16BE y | Start at world position (x, y) |
| Relative | UINT16BE x, UINT16BE y | Start at (x, y) relative to the top-left corner of the screen |
The rest of the path is one byte per step. The game moves the enemy one step every frame (15 per second). Each byte holds two signed 4-bit values:
| Bits | Meaning |
|---|---|
| 7-4 | Horizontal movement, -8 to +7 pixels (-8 is never used) |
| 3-0 | Vertical movement, -8 to +7 pixels (-8 is never used) |
When the end of the path is reached, the enemy keeps repeating the last step until it leaves the screen, and is then removed.
Source code
From re-gods, the open-source HTML5 port:
- src/game/pat-objects.js – PAT directory parser and path movement
Credits
This file format was reverse engineered by VorticonCmdr. If you find this information helpful in a project you're working on, please give credit where credit is due. (A link back to this wiki would be nice too!)