Map Tile Action Classes[ | ]
The first map layer is a nibble which defines what kind of action to perform when the tile is entered. There may be other implications of this as well. Thanks to its layout, this layer is also known as the "map nibble data". There are sixteen options (thanks to the fact a nibble is 4-bits long). This may change, but here are the current opinions on what the various action classes mean.
| Nibble Value | Meaning | |
|---|---|---|
| 0x0 | No Action | |
| 0x1 | Prints one or more strings & can change the Nibble/Byte tile data | |
| 0x2 | Check square | |
| 0x3 | Pointer to fixed encounter header which holds the pointers to the Fixed encounter data | |
| 0x4 | Used to mask other tiles with alternate tile graphic. Used to 'swap' tiles without using the c nibble action. Used for hidden bases, 'exploding' tiles, smashed doors, etc... | |
| 0x5 | Pointer to loot header which holds the pointers to the Loot Data | |
| 0x6 | Pointer to Special Building Data like Shops, Doctors, Libraries and the Ranger Center. It is also used to run multiple Special Actions in addition to handling buildings. | |
| 0x7 | Unused? | |
| 0x8 | Used for all popup window dialogue. Contains refs to valid responses and n/bb pairs on pass/fail | |
| 0x9 | Pointer to radiation header which holds the pointers to the Radiation Data | |
| 0xA | Pointer to transition header which holds the pointers to the Transition data | |
| 0xB | Impassable square. | |
| 0xC | Alters tiles. Can be used to alter any tile on a map. | |
| 0xD | Unused? | |
| 0xE | Unused? | |
| 0xF | Pointer to random encounter header which holds the pointers to the random encounter data |
NOTE 1: When a tile has no action or trigger, then it has an action of '00', so therefore Action Class 0's entry in the action class master table section of the Central MSQ Directory is a pointer to NULL.
NOTE 2: There is a pointer at offset 10h, its used with nibble 06. Its used as pointers inside the code to routines to execute depending on what the nibble is to do.